C3Stones

【面试专栏】Java8 - CompletableFuture，增强版Future

1. 简介

CompletableFuture是Java8的新特性，在Future基础上，增加流式计算、函数式编程、完成通知、自定义异常、多个Future组合处理等能力，使得在多线程协同处理时更加顺利。

2. 相关博客

【面试专栏】Java5 - Future，基本使用【面试专栏】Java5 - CompletionService，将异步执行与获取结果分离【面试专栏】Guava - ListenableFuture，避免Future获取阻塞问题，增加回调

3. CompletableFuture应用

3.1 supplyAsync/runAsync

supplyAsync和runAsync都可以创建CompletableFuture实例，并异步执行提交的任务。区别在于：supplyAsync带有返回值，runAsync无返回值。

创建带有返回值的异步任务

/**
 * 创建带有返回值的异步任务
 */
@Test
public void testSupplyAsync() throws ExecutionException, InterruptedException {
    CompletableFuture completableFuture = CompletableFuture.supplyAsync(() -> {
        log.info("任务执行中...");
        return Boolean.TRUE;
    });

    Boolean result = completableFuture.get();
    log.info("执行结果：" + result);
}

控制台输出：

19:56:10.381 [ForkJoinPool.commonPool-worker-1] INFO com.c3stones.test.CompletableFutureTest - 任务执行中...
19:56:10.393 [main] INFO com.c3stones.test.CompletableFutureTest - 执行结果：true

创建带有返回值的异步任务，并指定线程池

/**
 * 创建带有返回值的异步任务，并指定线程池
 */
@Test
public void testSupplyAsync2() throws ExecutionException, InterruptedException {
    ExecutorService executorService = Executors.newSingleThreadExecutor();

    CompletableFuture completableFuture = CompletableFuture.supplyAsync(() -> {
        log.info("任务执行中...");
        return Boolean.TRUE;
    }, executorService);

    Boolean result = completableFuture.get();
    log.info("执行结果：" + result);
}

控制台输出：

19:57:32.507 [pool-1-thread-1] INFO com.c3stones.test.CompletableFutureTest - 任务执行中...
19:57:32.513 [main] INFO com.c3stones.test.CompletableFutureTest - 执行结果：true

不指定线程池默认使用ForkJoinPool.commonPool()。

创建无返回值的异步任务

/**
 * 创建无返回值的异步任务
 */
@Test
public void testRunAsync() throws ExecutionException, InterruptedException {
    CompletableFuture completableFuture = CompletableFuture.runAsync(() -> {
        log.info("任务执行中...");
    });

    Void result = completableFuture.get();
    log.info("执行结果：" + result);
}

控制台输出：

19:59:29.721 [ForkJoinPool.commonPool-worker-1] INFO com.c3stones.test.CompletableFutureTest - 任务执行中...
19:59:29.729 [main] INFO com.c3stones.test.CompletableFutureTest - 执行结果：null

创建无返回值的异步任务，并指定线程池

/**
 * 创建无返回值的异步任务，并指定线程池
 */
@Test
public void testRunAsync2() throws ExecutionException, InterruptedException {
    ExecutorService executorService = Executors.newCachedThreadPool();

    CompletableFuture completableFuture = CompletableFuture.runAsync(() -> {
        log.info("任务执行中...");
    }, executorService);

    Void result = completableFuture.get();
    log.info("执行结果：" + result);
}

控制台输出：

20:00:06.732 [pool-1-thread-1] INFO com.c3stones.test.CompletableFutureTest - 任务执行中...
20:00:06.740 [main] INFO com.c3stones.test.CompletableFutureTest - 执行结果：null

3.2 流式连接函数

3.2.1 thenApply/thenApplyAsync

thenApply和thenApplyAsync都是任务执行完成后的回调函数，并将任务的返回结果作为入参，并带有返回值。区别在于：thenApply执行回调函数和任务使用的是同一线程，而thenApplyAsync会使用不同的线程，并且thenApplyAsync支持指定线程池。

thenApply

/**
 * 任务1执行完返回结果

 * 回调函数入参为任务1的返回结果，并带有返回值
 * 
 * 相同线程执行
 * 
 */
@Test
public void testThenApply() throws ExecutionException, InterruptedException {
    CompletableFuture completableFuture1 = CompletableFuture.supplyAsync(() -> {
        log.info("任务 1 执行中...");
        return 10;
    });

    CompletableFuture completableFuture2 = completableFuture1.thenApply((result) -> {
        log.info("回调函数执行中...");
        return result * 10;
    });

    log.info("任务 1 返回结果：" + completableFuture1.get());
    log.info("回调函数返回结果：" + completableFuture2.get());
}

控制台输出：

20:08:40.723 [ForkJoinPool.commonPool-worker-1] INFO com.c3stones.test.CompletableFutureTest - 任务 1 执行中...
20:08:40.730 [main] INFO com.c3stones.test.CompletableFutureTest - 回调函数执行中...
20:08:40.731 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 1 返回结果：10
20:08:40.731 [main] INFO com.c3stones.test.CompletableFutureTest - 回调函数返回结果：100

thenApplyAsync

/**
 * 任务1执行完返回结果

 * 回调函数入参为任务1的返回结果，并带有返回值
 * 
 * 提交给线程池，不同线程执行
 * 
 */
@Test
public void testThenApplyAsync() throws ExecutionException, InterruptedException {
    ExecutorService executorService = Executors.newCachedThreadPool();

    CompletableFuture completableFuture1 = CompletableFuture.supplyAsync(() -> {
        log.info("任务 1 执行中...");
        return 10;
    }, executorService);

    CompletableFuture completableFuture2 = completableFuture1.thenApplyAsync((result) -> {
        log.info("回调函数执行中...");
        return result * 10;
    }, executorService);

    log.info("任务 1 返回结果：" + completableFuture1.get());
    log.info("回调函数返回结果：" + completableFuture2.get());
}

控制台输出：

20:10:30.067 [pool-1-thread-1] INFO com.c3stones.test.CompletableFutureTest - 任务 1 执行中...
20:10:30.074 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 1 返回结果：10
20:10:30.075 [pool-1-thread-2] INFO com.c3stones.test.CompletableFutureTest - 回调函数执行中...
20:10:30.075 [main] INFO com.c3stones.test.CompletableFutureTest - 回调函数返回结果：100

3.2.2 thenAccept/thenAcceptAsync

thenAccept和thenAcceptAsync都是任务执行完成后的回调函数，并将任务的返回结果作为入参，但无返回值。区别在于：thenAccept执行回调函数和任务使用的是同一线程，而thenAcceptAsync会使用不同的线程，并且thenAcceptAsync支持指定线程池。

thenAccept

/**
 * 任务1执行完返回结果

 * 回调函数入参为任务1的返回结果，无返回值
 * 
 * 相同线程执行
 * 
 */
@Test
public void testThenAccept() throws ExecutionException, InterruptedException {
    CompletableFuture completableFuture1 = CompletableFuture.supplyAsync(() -> {
        log.info("任务 1 执行中...");
        return 10;
    });

    CompletableFuture completableFuture2 = completableFuture1.thenAccept((result) -> {
        log.info("回调函数执行中...");
    });

    log.info("任务 1 返回结果：" + completableFuture1.get());
    log.info("回调函数返回结果：" + completableFuture2.get());
}

控制台输出：

20:13:22.635 [ForkJoinPool.commonPool-worker-1] INFO com.c3stones.test.CompletableFutureTest - 任务 1 执行中...
20:13:22.641 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 1 返回结果：10
20:13:22.641 [ForkJoinPool.commonPool-worker-1] INFO com.c3stones.test.CompletableFutureTest - 回调函数执行中...
20:13:22.642 [main] INFO com.c3stones.test.CompletableFutureTest - 回调函数返回结果：null

thenAcceptAsync

/**
 * 任务1执行完返回结果

 * 回调函数入参为任务1的返回结果，无返回值
 * 
 * 提交给线程池，不同线程执行
 * 
 */
@Test
public void testThenAcceptAsync() throws ExecutionException, InterruptedException {
    ExecutorService executorService = Executors.newCachedThreadPool();

    CompletableFuture completableFuture1 = CompletableFuture.supplyAsync(() -> {
        log.info("任务 1 执行中...");
        return 10;
    }, executorService);

    CompletableFuture completableFuture2 = completableFuture1.thenAcceptAsync((result) -> {
        log.info("回调函数执行中...");
    }, executorService);

    log.info("任务 1 返回结果：" + completableFuture1.get());
    log.info("回调函数返回结果：" + completableFuture2.get());
}

控制台输出：

20:14:24.234 [pool-1-thread-1] INFO com.c3stones.test.CompletableFutureTest - 任务 1 执行中...
20:14:24.240 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 1 返回结果：10
20:14:24.303 [pool-1-thread-2] INFO com.c3stones.test.CompletableFutureTest - 回调函数执行中...
20:14:24.304 [main] INFO com.c3stones.test.CompletableFutureTest - 回调函数返回结果：null

3.2.3 thenRun/thenRunAsync

thenRun和thenRunAsync都是任务执行完成后的回调函数，但无入参，也无返回值。区别在于：thenRun执行回调函数和任务使用的是同一线程，而thenRunAsync会使用不同的线程，并且thenRunAsync支持指定线程池。

thenRun

/**
 * 任务1执行完返回结果

 * 回调函数无入参，无返回值
 * 
 * 相同线程执行
 * 
 */
@Test
public void testThenRun() throws ExecutionException, InterruptedException {
    CompletableFuture completableFuture1 = CompletableFuture.supplyAsync(() -> {
        log.info("任务 1 执行中...");
        return 10;
    });

    CompletableFuture completableFuture2 = completableFuture1.thenRun(() -> {
        log.info("回调函数执行中...");
    });

    log.info("任务 1 返回结果：" + completableFuture1.get());
    log.info("回调函数返回结果：" + completableFuture2.get());
}

控制台输出：

20:17:37.329 [ForkJoinPool.commonPool-worker-1] INFO com.c3stones.test.CompletableFutureTest - 任务 1 执行中...
20:17:37.335 [ForkJoinPool.commonPool-worker-1] INFO com.c3stones.test.CompletableFutureTest - 回调函数执行中...
20:17:37.335 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 1 返回结果：10
20:17:37.335 [main] INFO com.c3stones.test.CompletableFutureTest - 回调函数返回结果：null

thenRunAsync

/**
 * 任务1执行完返回结果

 * 回调函数无入参，无返回值
 * 
 * 提交给线程池，不同线程执行
 * 
 */
@Test
public void testThenRunAsync() throws ExecutionException, InterruptedException {
    ExecutorService executorService = Executors.newCachedThreadPool();

    CompletableFuture completableFuture1 = CompletableFuture.supplyAsync(() -> {
        log.info("任务 1 执行中...");
        return 10;
    }, executorService);

    CompletableFuture completableFuture2 = completableFuture1.thenRunAsync(() -> {
        log.info("回调函数执行中...");
    }, executorService);

    log.info("任务 1 返回结果：" + completableFuture1.get());
    log.info("回调函数返回结果：" + completableFuture2.get());
}

控制台输出：

20:18:39.630 [pool-1-thread-1] INFO com.c3stones.test.CompletableFutureTest - 任务 1 执行中...
20:18:39.638 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 1 返回结果：10
20:18:39.656 [pool-1-thread-2] INFO com.c3stones.test.CompletableFutureTest - 回调函数执行中...
20:18:39.656 [main] INFO com.c3stones.test.CompletableFutureTest - 回调函数返回结果：null

3.2.4 whenComplete/whenCompleteAsync

whenComplete和whenCompleteAsync都是任务执行完成后的回调函数，带有两个参数，参数1为任务指定的返回结果，参数2为任务2执行时抛出的异常。调用get方法获取任务的执行结果时，如果任务执行正常，则正常返回结果，如果执行异常，则抛出异常。区别在于：whenComplete执行回调函数和任务使用的是同一线程，而whenCompleteAsync会使用不同的线程，并且whenCompleteAsync支持指定线程池。

whenComplete

/**
 * 任务1执行成功

 * 回调函数入参1为任务1的返回结果，入参2为null
 * 
 * 相同线程执行
 * 
 */
@Test
public void testWhenComplete() throws ExecutionException, InterruptedException {
    CompletableFuture completableFuture1 = CompletableFuture.supplyAsync(() -> {
        log.info("任务 1 执行中...");
        return 10;
    });

    CompletableFuture completableFuture2 = completableFuture1.whenComplete((result, exception) -> {
        if (exception != null) {
            log.error("任务 1 返回异常：" + exception.getMessage());
        } else {
            log.info("任务 1 返回结果：" + result);
        }
    });

    log.info("任务 1 返回结果：" + completableFuture1.get());
    log.info("回调函数返回结果：" + completableFuture2.get());
}

控制台输出：

20:24:25.589 [ForkJoinPool.commonPool-worker-1] INFO com.c3stones.test.CompletableFutureTest - 任务 1 执行中...
20:24:25.597 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 1 返回结果：10
20:24:25.597 [ForkJoinPool.commonPool-worker-1] INFO com.c3stones.test.CompletableFutureTest - 任务 1 返回结果：10
20:24:25.598 [main] INFO com.c3stones.test.CompletableFutureTest - 回调函数返回结果：10

/**
 * 任务1执行抛出异常

 * 回调函数入参1为null.入参2为任务1抛出的异常
 * 
 * 相同线程执行
 * 
 */
@Test
public void testWhenCompleteException() throws ExecutionException, InterruptedException {
    CompletableFuture completableFuture1 = CompletableFuture.supplyAsync(() -> {
        log.info("任务 1 执行中...");
        int a = 1 / 0;
        return 10;
    });

    CompletableFuture completableFuture2 = completableFuture1.whenComplete((result, exception) -> {
        if (exception != null) {
            log.error("任务 1 返回异常：" + exception.getMessage());
        } else {
            log.info("任务 1 返回结果：" + result);
        }
    });

    log.info("任务 1 返回结果：" + completableFuture1.get());
    log.info("回调函数返回结果：" + completableFuture2.get());
}

控制台输出：

20:25:34.521 [ForkJoinPool.commonPool-worker-1] INFO com.c3stones.test.CompletableFutureTest - 任务 1 执行中...
20:25:34.529 [ForkJoinPool.commonPool-worker-1] ERROR com.c3stones.test.CompletableFutureTest - 任务 1 返回异常：java.lang.ArithmeticException: / by zero

java.util.concurrent.ExecutionException: java.lang.ArithmeticException: / by zero

	at java.util.concurrent.CompletableFuture.reportGet(CompletableFuture.java:357)
	at java.util.concurrent.CompletableFuture.get(CompletableFuture.java:1895)
	at com.c3stones.test.CompletableFutureTest.testWhenCompleteException(CompletableFutureTest.java:263)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.platform.commons.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:725)
	at org.junit.jupiter.engine.execution.MethodInvocation.proceed(MethodInvocation.java:60)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain$ValidatingInvocation.proceed(InvocationInterceptorChain.java:131)
	at org.junit.jupiter.engine.extension.TimeoutExtension.intercept(TimeoutExtension.java:149)
	at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestableMethod(TimeoutExtension.java:140)
	at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestMethod(TimeoutExtension.java:84)
	at org.junit.jupiter.engine.execution.ExecutableInvoker$ReflectiveInterceptorCall.lambda$ofVoidMethod$0(ExecutableInvoker.java:115)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.lambda$invoke$0(ExecutableInvoker.java:105)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain$InterceptedInvocation.proceed(InvocationInterceptorChain.java:106)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.proceed(InvocationInterceptorChain.java:64)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.chainAndInvoke(InvocationInterceptorChain.java:45)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.invoke(InvocationInterceptorChain.java:37)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:104)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:98)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$invokeTestMethod$7(TestMethodTestDescriptor.java:214)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.invokeTestMethod(TestMethodTestDescriptor.java:210)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:135)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:66)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:151)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at java.util.ArrayList.forEach(ArrayList.java:1249)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at java.util.ArrayList.forEach(ArrayList.java:1249)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:35)
	at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:57)
	at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:54)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:107)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:88)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.lambda$execute$0(EngineExecutionOrchestrator.java:54)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.withInterceptedStreams(EngineExecutionOrchestrator.java:67)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:52)
	at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:114)
	at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:86)
	at org.junit.platform.launcher.core.DefaultLauncherSession$DelegatingLauncher.execute(DefaultLauncherSession.java:86)
	at org.junit.platform.launcher.core.SessionPerRequestLauncher.execute(SessionPerRequestLauncher.java:53)
	at com.intellij.junit5.JUnit5IdeaTestRunner.startRunnerWithArgs(JUnit5IdeaTestRunner.java:71)
	at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
	at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:235)
	at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:54)
Caused by: java.lang.ArithmeticException: / by zero
	at com.c3stones.test.CompletableFutureTest.lambda$testWhenCompleteException$18(CompletableFutureTest.java:251)
	at java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1590)
	at java.util.concurrent.CompletableFuture$AsyncSupply.exec(CompletableFuture.java:1582)
	at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:289)
	at java.util.concurrent.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1056)
	at java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1692)
	at java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:157)

whenCompleteAsync

/**
 * 任务1执行完返回结果

 * 回调函数入参1为null.入参2为任务1抛出的异常
 * 
 * 提交给线程池，不同线程执行
 * 
 */
@Test
public void testWhenCompleteAsync() throws ExecutionException, InterruptedException {
    ExecutorService executorService = Executors.newCachedThreadPool();

    CompletableFuture completableFuture1 = CompletableFuture.supplyAsync(() -> {
        log.info("任务 1 执行中...");
        return 10;
    }, executorService);

    CompletableFuture completableFuture2 = completableFuture1.whenCompleteAsync((result, exception) -> {
        if (exception != null) {
            log.error("任务 1 返回异常：" + exception.getMessage());
        } else {
            log.info("任务 1 返回结果：" + result);
        }
    }, executorService);

    log.info("任务 1 返回结果：" + completableFuture1.get());
    log.info("回调函数返回结果：" + completableFuture2.get());
}

控制台输出：

20:37:29.881 [pool-1-thread-1] INFO com.c3stones.test.CompletableFutureTest - 任务 1 执行中...
20:37:29.886 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 1 返回结果：10
20:37:29.887 [pool-1-thread-2] INFO com.c3stones.test.CompletableFutureTest - 任务 1 返回结果：10
20:37:29.887 [main] INFO com.c3stones.test.CompletableFutureTest - 回调函数返回结果：10

/**
 * 任务1执行抛出异常

 * 回调函数入参1为null.入参2为任务1抛出的异常
 * 
 * 提交给线程池，不同线程执行
 * 
 */
@Test
public void testWhenCompleteAsyncException() throws ExecutionException, InterruptedException {
    ExecutorService executorService = Executors.newCachedThreadPool();

    CompletableFuture completableFuture1 = CompletableFuture.supplyAsync(() -> {
        log.info("任务 1 执行中...");
        int a = 1 / 0;
        return 10;
    }, executorService);

    CompletableFuture completableFuture2 = completableFuture1.whenCompleteAsync((result, exception) -> {
        if (exception != null) {
            log.error("任务 1 返回异常：" + exception.getMessage());
        } else {
            log.info("任务 1 返回结果：" + result);
        }
    }, executorService);

    log.info("任务 1 返回结果：" + completableFuture1.get());
    log.info("回调函数返回结果：" + completableFuture2.get());
}

控制台输出：

20:39:00.814 [pool-1-thread-1] INFO com.c3stones.test.CompletableFutureTest - 任务 1 执行中...
20:39:00.821 [pool-1-thread-2] ERROR com.c3stones.test.CompletableFutureTest - 任务 1 返回异常：java.lang.ArithmeticException: / by zero

java.util.concurrent.ExecutionException: java.lang.ArithmeticException: / by zero

	at java.util.concurrent.CompletableFuture.reportGet(CompletableFuture.java:357)
	at java.util.concurrent.CompletableFuture.get(CompletableFuture.java:1895)
	at com.c3stones.test.CompletableFutureTest.testWhenCompleteAsyncException(CompletableFutureTest.java:320)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.platform.commons.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:725)
	at org.junit.jupiter.engine.execution.MethodInvocation.proceed(MethodInvocation.java:60)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain$ValidatingInvocation.proceed(InvocationInterceptorChain.java:131)
	at org.junit.jupiter.engine.extension.TimeoutExtension.intercept(TimeoutExtension.java:149)
	at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestableMethod(TimeoutExtension.java:140)
	at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestMethod(TimeoutExtension.java:84)
	at org.junit.jupiter.engine.execution.ExecutableInvoker$ReflectiveInterceptorCall.lambda$ofVoidMethod$0(ExecutableInvoker.java:115)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.lambda$invoke$0(ExecutableInvoker.java:105)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain$InterceptedInvocation.proceed(InvocationInterceptorChain.java:106)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.proceed(InvocationInterceptorChain.java:64)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.chainAndInvoke(InvocationInterceptorChain.java:45)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.invoke(InvocationInterceptorChain.java:37)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:104)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:98)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$invokeTestMethod$7(TestMethodTestDescriptor.java:214)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.invokeTestMethod(TestMethodTestDescriptor.java:210)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:135)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:66)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:151)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at java.util.ArrayList.forEach(ArrayList.java:1249)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at java.util.ArrayList.forEach(ArrayList.java:1249)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:35)
	at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:57)
	at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:54)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:107)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:88)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.lambda$execute$0(EngineExecutionOrchestrator.java:54)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.withInterceptedStreams(EngineExecutionOrchestrator.java:67)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:52)
	at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:114)
	at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:86)
	at org.junit.platform.launcher.core.DefaultLauncherSession$DelegatingLauncher.execute(DefaultLauncherSession.java:86)
	at org.junit.platform.launcher.core.SessionPerRequestLauncher.execute(SessionPerRequestLauncher.java:53)
	at com.intellij.junit5.JUnit5IdeaTestRunner.startRunnerWithArgs(JUnit5IdeaTestRunner.java:71)
	at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
	at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:235)
	at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:54)
Caused by: java.lang.ArithmeticException: / by zero
	at com.c3stones.test.CompletableFutureTest.lambda$testWhenCompleteAsyncException$22(CompletableFutureTest.java:308)
	at java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1590)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at java.lang.Thread.run(Thread.java:745)

3.2.5 handle/handleAsync

handle和handleAsync都是任务执行完成后的回调函数，带有两个参数，参数1为任务指定的返回结果，参数2为任务2执行时抛出的异常，并且带有返回值。调用get方法获取任务的执行结果时，如果任务执行正常，则正常返回结果，如果执行异常，则抛出异常。区别在于：handle执行回调函数和任务使用的是同一线程，而handleAsync会使用不同的线程，并且handleAsync支持指定线程池。

handle

/**
 * 任务1执行完返回结果

 * 回调函数入参1为任务1的返回结果，入参2为null，并带有返回值
 * 
 * 相同线程执行
 * 
 */
@Test
public void testHandle() throws ExecutionException, InterruptedException {
    CompletableFuture completableFuture1 = CompletableFuture.supplyAsync(() -> {
        log.info("任务 1 执行中...");
        return 10;
    });

    CompletableFuture completableFuture2 = completableFuture1.handle((result, exception) -> {
        if (exception != null) {
            log.error("任务 1 返回异常：" + exception.getMessage());
        } else {
            log.info("任务 1 返回结果：" + result);
        }
        return result * 10;
    });

    log.info("任务 1 返回结果：" + completableFuture1.get());
    log.info("回调函数返回结果：" + completableFuture2.get());
}

控制台输出：

20:43:18.876 [ForkJoinPool.commonPool-worker-1] INFO com.c3stones.test.CompletableFutureTest - 任务 1 执行中...
20:43:18.881 [ForkJoinPool.commonPool-worker-1] INFO com.c3stones.test.CompletableFutureTest - 任务 1 返回结果：10
20:43:18.881 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 1 返回结果：10
20:43:18.881 [main] INFO com.c3stones.test.CompletableFutureTest - 回调函数返回结果：100

/**
 * 任务1执行抛出异常

 * 回调函数入参1为任务1的返回结果，入参2为null，并带有返回值
 * 
 * 相同线程执行
 * 
 */
@Test
public void testHandleException() throws ExecutionException, InterruptedException {
    CompletableFuture completableFuture1 = CompletableFuture.supplyAsync(() -> {
        log.info("任务 1 执行中...");
        int a = 1 / 0;
        return 10;
    });

    CompletableFuture completableFuture2 = completableFuture1.handle((result, exception) -> {
        if (exception != null) {
            log.error("任务 1 返回异常：" + exception.getMessage());
        } else {
            log.info("任务 1 返回结果：" + result);
        }
        return result * 10;
    });

    log.info("任务 1 返回结果：" + completableFuture1.get());
    log.info("回调函数返回结果：" + completableFuture2.get());
}

控制台输出：

20:45:24.873 [ForkJoinPool.commonPool-worker-1] INFO com.c3stones.test.CompletableFutureTest - 任务 1 执行中...
20:45:24.888 [main] ERROR com.c3stones.test.CompletableFutureTest - 任务 1 返回异常：java.lang.ArithmeticException: / by zero

java.util.concurrent.ExecutionException: java.lang.ArithmeticException: / by zero

	at java.util.concurrent.CompletableFuture.reportGet(CompletableFuture.java:357)
	at java.util.concurrent.CompletableFuture.get(CompletableFuture.java:1895)
	at com.c3stones.test.CompletableFutureTest.testHandleException(CompletableFutureTest.java:375)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.platform.commons.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:725)
	at org.junit.jupiter.engine.execution.MethodInvocation.proceed(MethodInvocation.java:60)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain$ValidatingInvocation.proceed(InvocationInterceptorChain.java:131)
	at org.junit.jupiter.engine.extension.TimeoutExtension.intercept(TimeoutExtension.java:149)
	at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestableMethod(TimeoutExtension.java:140)
	at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestMethod(TimeoutExtension.java:84)
	at org.junit.jupiter.engine.execution.ExecutableInvoker$ReflectiveInterceptorCall.lambda$ofVoidMethod$0(ExecutableInvoker.java:115)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.lambda$invoke$0(ExecutableInvoker.java:105)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain$InterceptedInvocation.proceed(InvocationInterceptorChain.java:106)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.proceed(InvocationInterceptorChain.java:64)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.chainAndInvoke(InvocationInterceptorChain.java:45)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.invoke(InvocationInterceptorChain.java:37)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:104)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:98)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$invokeTestMethod$7(TestMethodTestDescriptor.java:214)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.invokeTestMethod(TestMethodTestDescriptor.java:210)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:135)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:66)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:151)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at java.util.ArrayList.forEach(ArrayList.java:1249)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at java.util.ArrayList.forEach(ArrayList.java:1249)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:35)
	at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:57)
	at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:54)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:107)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:88)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.lambda$execute$0(EngineExecutionOrchestrator.java:54)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.withInterceptedStreams(EngineExecutionOrchestrator.java:67)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:52)
	at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:114)
	at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:86)
	at org.junit.platform.launcher.core.DefaultLauncherSession$DelegatingLauncher.execute(DefaultLauncherSession.java:86)
	at org.junit.platform.launcher.core.SessionPerRequestLauncher.execute(SessionPerRequestLauncher.java:53)
	at com.intellij.junit5.JUnit5IdeaTestRunner.startRunnerWithArgs(JUnit5IdeaTestRunner.java:71)
	at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
	at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:235)
	at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:54)
Caused by: java.lang.ArithmeticException: / by zero
	at com.c3stones.test.CompletableFutureTest.lambda$testHandleException$26(CompletableFutureTest.java:362)
	at java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1590)
	at java.util.concurrent.CompletableFuture$AsyncSupply.exec(CompletableFuture.java:1582)
	at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:289)
	at java.util.concurrent.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1056)
	at java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1692)
	at java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:157)

handleAsync

/**
 * 任务1执行完返回结果

 * 回调函数入参1为任务1的返回结果，入参2为null，并带有返回值
 * 
 * 提交给线程池，不同线程执行
 * 
 */
@Test
public void testHandleAsync() throws ExecutionException, InterruptedException {
    ExecutorService executorService = Executors.newCachedThreadPool();

    CompletableFuture completableFuture1 = CompletableFuture.supplyAsync(() -> {
        log.info("任务 1 执行中...");
        return 10;
    }, executorService);

    CompletableFuture completableFuture2 = completableFuture1.handleAsync((result, exception) -> {
        if (exception != null) {
            log.error("任务 1 返回异常：" + exception.getMessage());
        } else {
            log.info("任务 1 返回结果：" + result);
        }
        return result * 10;
    }, executorService);

    log.info("任务 1 返回结果：" + completableFuture1.get());
    log.info("回调函数返回结果：" + completableFuture2.get());
}

控制台输出：

20:46:43.338 [pool-1-thread-1] INFO com.c3stones.test.CompletableFutureTest - 任务 1 执行中...
20:46:43.345 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 1 返回结果：10
20:46:43.347 [pool-1-thread-2] INFO com.c3stones.test.CompletableFutureTest - 任务 1 返回结果：10
20:46:43.347 [main] INFO com.c3stones.test.CompletableFutureTest - 回调函数返回结果：100

/**
 * 任务1执行抛出异常

 * 回调函数入参1为任务1的返回结果，入参2为null，并带有返回值
 * 
 * 提交给线程池，不同线程执行
 * 
 */
@Test
public void testHandleAsyncException() throws ExecutionException, InterruptedException {
    ExecutorService executorService = Executors.newCachedThreadPool();

    CompletableFuture completableFuture1 = CompletableFuture.supplyAsync(() -> {
        log.info("任务 1 执行中...");
        int a = 1 / 0;
        return 10;
    }, executorService);

    CompletableFuture completableFuture2 = completableFuture1.handleAsync((result, exception) -> {
        if (exception != null) {
            log.error("任务 1 返回异常：" + exception.getMessage());
        } else {
            log.info("任务 1 返回结果：" + result);
        }
        return result * 10;
    }, executorService);

    log.info("任务 1 返回结果：" + completableFuture1.get());
    log.info("回调函数返回结果：" + completableFuture2.get());
}

控制台输出：

20:47:22.106 [pool-1-thread-1] INFO com.c3stones.test.CompletableFutureTest - 任务 1 执行中...
20:47:22.113 [pool-1-thread-2] ERROR com.c3stones.test.CompletableFutureTest - 任务 1 返回异常：java.lang.ArithmeticException: / by zero

java.util.concurrent.ExecutionException: java.lang.ArithmeticException: / by zero

	at java.util.concurrent.CompletableFuture.reportGet(CompletableFuture.java:357)
	at java.util.concurrent.CompletableFuture.get(CompletableFuture.java:1895)
	at com.c3stones.test.CompletableFutureTest.testHandleAsyncException(CompletableFutureTest.java:434)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.platform.commons.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:725)
	at org.junit.jupiter.engine.execution.MethodInvocation.proceed(MethodInvocation.java:60)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain$ValidatingInvocation.proceed(InvocationInterceptorChain.java:131)
	at org.junit.jupiter.engine.extension.TimeoutExtension.intercept(TimeoutExtension.java:149)
	at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestableMethod(TimeoutExtension.java:140)
	at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestMethod(TimeoutExtension.java:84)
	at org.junit.jupiter.engine.execution.ExecutableInvoker$ReflectiveInterceptorCall.lambda$ofVoidMethod$0(ExecutableInvoker.java:115)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.lambda$invoke$0(ExecutableInvoker.java:105)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain$InterceptedInvocation.proceed(InvocationInterceptorChain.java:106)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.proceed(InvocationInterceptorChain.java:64)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.chainAndInvoke(InvocationInterceptorChain.java:45)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.invoke(InvocationInterceptorChain.java:37)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:104)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:98)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$invokeTestMethod$7(TestMethodTestDescriptor.java:214)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.invokeTestMethod(TestMethodTestDescriptor.java:210)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:135)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:66)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:151)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at java.util.ArrayList.forEach(ArrayList.java:1249)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at java.util.ArrayList.forEach(ArrayList.java:1249)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:35)
	at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:57)
	at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:54)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:107)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:88)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.lambda$execute$0(EngineExecutionOrchestrator.java:54)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.withInterceptedStreams(EngineExecutionOrchestrator.java:67)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:52)
	at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:114)
	at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:86)
	at org.junit.platform.launcher.core.DefaultLauncherSession$DelegatingLauncher.execute(DefaultLauncherSession.java:86)
	at org.junit.platform.launcher.core.SessionPerRequestLauncher.execute(SessionPerRequestLauncher.java:53)
	at com.intellij.junit5.JUnit5IdeaTestRunner.startRunnerWithArgs(JUnit5IdeaTestRunner.java:71)
	at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
	at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:235)
	at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:54)
Caused by: java.lang.ArithmeticException: / by zero
	at com.c3stones.test.CompletableFutureTest.lambda$testHandleAsyncException$30(CompletableFutureTest.java:421)
	at java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1590)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at java.lang.Thread.run(Thread.java:745)

3.3 多任务组合

3.3.1 thenCombine/thenCombineAsync

thenCombine和thenCombineAsync都是将两个异步任务组合后处理。当两个任务都执行完成后，执行回调函数。回调函数会将两个任务的返回结果作为入参，并带有返回值。如果两个任务有一个执行异常，则抛出异常。区别在于：thenCombine执行回调函数时会公用执行两个任务的其中一个的线程，而thenCombineAsync会使用不同的线程，并且thenCombineAsync支持指定线程池。

thenCombine

/**
 * 任务1和任务2都执行成功，再执行回调函数

 * 回调函数入参为任务1和任务2的返回结果，并带有返回值
 * 
 * 回调函数公用两个任务其中一个线程执行
 * 
 */
@Test
public void testThenCombine() throws ExecutionException, InterruptedException {
    CompletableFuture completableFuture1 = CompletableFuture.supplyAsync(() -> {
        log.info("任务 1 执行中...");
        return 10;
    });

    CompletableFuture completableFuture2 = CompletableFuture.supplyAsync(() -> {
        log.info("任务 2 执行中...");
        return 20;
    });

    CompletableFuture completableFuture3 = completableFuture1.thenCombine(completableFuture2, (result1, result2) -> {
        log.info("回调函数获取到 任务 1 结果：" + result1 + "，获取到任务 2 结果：" + result2);
        log.info("回调函数执行中...");
        return result1 + result2;
    });

    log.info("任务 1 返回结果：" + completableFuture1.get());
    log.info("任务 2 返回结果：" + completableFuture2.get());
    log.info("回调函数返回结果：" + completableFuture3.get());
}

控制台输出：

21:15:55.676 [ForkJoinPool.commonPool-worker-2] INFO com.c3stones.test.CompletableFutureTest - 任务 2 执行中...
21:15:55.676 [ForkJoinPool.commonPool-worker-1] INFO com.c3stones.test.CompletableFutureTest - 任务 1 执行中...
21:15:55.684 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 1 返回结果：10
21:15:55.684 [ForkJoinPool.commonPool-worker-1] INFO com.c3stones.test.CompletableFutureTest - 回调函数获取到 任务 1 结果：10，获取到任务 2 结果：20
21:15:55.684 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 2 返回结果：20
21:15:55.684 [ForkJoinPool.commonPool-worker-1] INFO com.c3stones.test.CompletableFutureTest - 回调函数执行中...
21:15:55.684 [main] INFO com.c3stones.test.CompletableFutureTest - 回调函数返回结果：30

/**
 * 任务1执行成功，任务2执行失败，再执行回调函数

 * 回调函数入参为任务1和任务2的返回结果，并带有返回值
 * 
 * 回调函数公用两个任务其中一个线程执行
 * 
 */
@Test
public void testThenCombineException() throws ExecutionException, InterruptedException {
    CompletableFuture completableFuture1 = CompletableFuture.supplyAsync(() -> {
        log.info("任务 1 执行中...");
        return 10;
    });

    CompletableFuture completableFuture2 = CompletableFuture.supplyAsync(() -> {
        log.info("任务 2 执行中...");
        int a = 1 / 0;
        return 20;
    });

    CompletableFuture completableFuture3 = completableFuture1.thenCombine(completableFuture2, (result1, result2) -> {
        log.info("回调函数获取到 任务 1 结果：" + result1 + "，获取到任务 2 结果：" + result2);
        log.info("回调函数执行中...");
        return result1 + result2;
    });

    log.info("任务 1 返回结果：" + completableFuture1.get());
    log.info("任务 2 返回结果：" + completableFuture2.get());
    log.info("回调函数返回结果：" + completableFuture3.get());
}

控制台输出：

21:17:24.832 [ForkJoinPool.commonPool-worker-1] INFO com.c3stones.test.CompletableFutureTest - 任务 1 执行中...
21:17:24.832 [ForkJoinPool.commonPool-worker-2] INFO com.c3stones.test.CompletableFutureTest - 任务 2 执行中...
21:17:24.839 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 1 返回结果：10

java.util.concurrent.ExecutionException: java.lang.ArithmeticException: / by zero

	at java.util.concurrent.CompletableFuture.reportGet(CompletableFuture.java:357)
	at java.util.concurrent.CompletableFuture.get(CompletableFuture.java:1895)
	at com.c3stones.test.CompletableFutureTest.testThenCombineException(CompletableFutureTest.java:495)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.platform.commons.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:725)
	at org.junit.jupiter.engine.execution.MethodInvocation.proceed(MethodInvocation.java:60)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain$ValidatingInvocation.proceed(InvocationInterceptorChain.java:131)
	at org.junit.jupiter.engine.extension.TimeoutExtension.intercept(TimeoutExtension.java:149)
	at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestableMethod(TimeoutExtension.java:140)
	at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestMethod(TimeoutExtension.java:84)
	at org.junit.jupiter.engine.execution.ExecutableInvoker$ReflectiveInterceptorCall.lambda$ofVoidMethod$0(ExecutableInvoker.java:115)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.lambda$invoke$0(ExecutableInvoker.java:105)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain$InterceptedInvocation.proceed(InvocationInterceptorChain.java:106)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.proceed(InvocationInterceptorChain.java:64)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.chainAndInvoke(InvocationInterceptorChain.java:45)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.invoke(InvocationInterceptorChain.java:37)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:104)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:98)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$invokeTestMethod$7(TestMethodTestDescriptor.java:214)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.invokeTestMethod(TestMethodTestDescriptor.java:210)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:135)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:66)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:151)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at java.util.ArrayList.forEach(ArrayList.java:1249)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at java.util.ArrayList.forEach(ArrayList.java:1249)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:35)
	at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:57)
	at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:54)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:107)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:88)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.lambda$execute$0(EngineExecutionOrchestrator.java:54)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.withInterceptedStreams(EngineExecutionOrchestrator.java:67)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:52)
	at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:114)
	at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:86)
	at org.junit.platform.launcher.core.DefaultLauncherSession$DelegatingLauncher.execute(DefaultLauncherSession.java:86)
	at org.junit.platform.launcher.core.SessionPerRequestLauncher.execute(SessionPerRequestLauncher.java:53)
	at com.intellij.junit5.JUnit5IdeaTestRunner.startRunnerWithArgs(JUnit5IdeaTestRunner.java:71)
	at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
	at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:235)
	at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:54)
Caused by: java.lang.ArithmeticException: / by zero
	at com.c3stones.test.CompletableFutureTest.lambda$testThenCombineException$36(CompletableFutureTest.java:484)
	at java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1590)
	at java.util.concurrent.CompletableFuture$AsyncSupply.exec(CompletableFuture.java:1582)
	at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:289)
	at java.util.concurrent.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1056)
	at java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1692)
	at java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:157)

thenCombineAsync

/**
 * 任务1和任务2都执行成功，再执行回调函数

 * 回调函数入参为任务1和任务2的返回结果，并带有返回值
 * 
 * 提交给线程池，不同线程执行
 * 
 */
@Test
public void testThenCombineAsync() throws ExecutionException, InterruptedException {
    ExecutorService executorService = Executors.newCachedThreadPool();

    CompletableFuture completableFuture1 = CompletableFuture.supplyAsync(() -> {
        log.info("任务 1 执行中...");
        return 10;
    }, executorService);

    CompletableFuture completableFuture2 = CompletableFuture.supplyAsync(() -> {
        log.info("任务 2 执行中...");
        return 20;
    }, executorService);

    CompletableFuture completableFuture3 = completableFuture1.thenCombineAsync(completableFuture2, (result1, result2) -> {
        log.info("回调函数获取到 任务 1 结果：" + result1 + "，获取到任务 2 结果：" + result2);
        log.info("回调函数执行中...");
        return result1 + result2;
    }, executorService);

    log.info("任务 1 返回结果：" + completableFuture1.get());
    log.info("任务 2 返回结果：" + completableFuture2.get());
    log.info("回调函数返回结果：" + completableFuture3.get());
}

控制台输出：

21:19:29.638 [pool-1-thread-2] INFO com.c3stones.test.CompletableFutureTest - 任务 2 执行中...
21:19:29.636 [pool-1-thread-1] INFO com.c3stones.test.CompletableFutureTest - 任务 1 执行中...
21:19:29.642 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 1 返回结果：10
21:19:29.642 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 2 返回结果：20
21:19:29.645 [pool-1-thread-3] INFO com.c3stones.test.CompletableFutureTest - 回调函数获取到 任务 1 结果：10，获取到任务 2 结果：20
21:19:29.645 [pool-1-thread-3] INFO com.c3stones.test.CompletableFutureTest - 回调函数执行中...
21:19:29.645 [main] INFO com.c3stones.test.CompletableFutureTest - 回调函数返回结果：30

/**
 * 任务1执行成功，任务2执行失败，再执行回调函数

 * 回调函数入参为任务1和任务2的返回结果，并带有返回值
 * 
 * 提交给线程池，不同线程执行
 * 
 */
@Test
public void testThenCombineAsyncException() throws ExecutionException, InterruptedException {
    ExecutorService executorService = Executors.newCachedThreadPool();

    CompletableFuture completableFuture1 = CompletableFuture.supplyAsync(() -> {
        log.info("任务 1 执行中...");
        return 10;
    }, executorService);

    CompletableFuture completableFuture2 = CompletableFuture.supplyAsync(() -> {
        log.info("任务 2 执行中...");
        int a = 1 / 0;
        return 20;
    }, executorService);

    CompletableFuture completableFuture3 = completableFuture1.thenCombineAsync(completableFuture2, (result1, result2) -> {
        log.info("回调函数获取到 任务 1 结果：" + result1 + "，获取到任务 2 结果：" + result2);
        log.info("回调函数执行中...");
        return result1 + result2;
    }, executorService);

    log.info("任务 1 返回结果：" + completableFuture1.get());
    log.info("任务 2 返回结果：" + completableFuture2.get());
    log.info("回调函数返回结果：" + completableFuture3.get());
}

控制台输出：

21:23:26.457 [pool-1-thread-1] INFO com.c3stones.test.CompletableFutureTest - 任务 1 执行中...
21:23:26.463 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 1 返回结果：10
21:23:26.467 [pool-1-thread-2] INFO com.c3stones.test.CompletableFutureTest - 任务 2 执行中...

java.util.concurrent.ExecutionException: java.lang.ArithmeticException: / by zero

	at java.util.concurrent.CompletableFuture.reportGet(CompletableFuture.java:357)
	at java.util.concurrent.CompletableFuture.get(CompletableFuture.java:1895)
	at com.c3stones.test.CompletableFutureTest.testThenCombineAsyncException(CompletableFutureTest.java:560)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.platform.commons.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:725)
	at org.junit.jupiter.engine.execution.MethodInvocation.proceed(MethodInvocation.java:60)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain$ValidatingInvocation.proceed(InvocationInterceptorChain.java:131)
	at org.junit.jupiter.engine.extension.TimeoutExtension.intercept(TimeoutExtension.java:149)
	at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestableMethod(TimeoutExtension.java:140)
	at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestMethod(TimeoutExtension.java:84)
	at org.junit.jupiter.engine.execution.ExecutableInvoker$ReflectiveInterceptorCall.lambda$ofVoidMethod$0(ExecutableInvoker.java:115)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.lambda$invoke$0(ExecutableInvoker.java:105)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain$InterceptedInvocation.proceed(InvocationInterceptorChain.java:106)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.proceed(InvocationInterceptorChain.java:64)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.chainAndInvoke(InvocationInterceptorChain.java:45)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.invoke(InvocationInterceptorChain.java:37)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:104)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:98)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$invokeTestMethod$7(TestMethodTestDescriptor.java:214)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.invokeTestMethod(TestMethodTestDescriptor.java:210)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:135)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:66)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:151)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at java.util.ArrayList.forEach(ArrayList.java:1249)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at java.util.ArrayList.forEach(ArrayList.java:1249)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:35)
	at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:57)
	at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:54)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:107)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:88)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.lambda$execute$0(EngineExecutionOrchestrator.java:54)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.withInterceptedStreams(EngineExecutionOrchestrator.java:67)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:52)
	at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:114)
	at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:86)
	at org.junit.platform.launcher.core.DefaultLauncherSession$DelegatingLauncher.execute(DefaultLauncherSession.java:86)
	at org.junit.platform.launcher.core.SessionPerRequestLauncher.execute(SessionPerRequestLauncher.java:53)
	at com.intellij.junit5.JUnit5IdeaTestRunner.startRunnerWithArgs(JUnit5IdeaTestRunner.java:71)
	at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
	at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:235)
	at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:54)
Caused by: java.lang.ArithmeticException: / by zero
	at com.c3stones.test.CompletableFutureTest.lambda$testThenCombineAsyncException$42(CompletableFutureTest.java:549)
	at java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1590)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at java.lang.Thread.run(Thread.java:745)

3.3.2 thenAcceptBoth/thenAcceptBothAsync

thenAcceptBoth和thenAcceptBothAsync都是将两个异步任务组合后处理。当两个任务都执行完成后，执行回调函数。回调函数会将两个任务的返回结果作为入参，但无返回值。如果两个任务有一个执行异常，则抛出异常。区别在于：thenAcceptBoth执行回调函数时会公用执行两个任务的其中一个的线程，而thenAcceptBothAsync会使用不同的线程，并且thenAcceptBothAsync支持指定线程池。

thenAcceptBoth

/**
 * 任务1和任务2都执行成功，再执行回调函数

 * 回调函数入参为任务1和任务2的返回结果，无返回值
 * 
 * 回调函数公用两个任务其中一个线程执行
 * 
 */
@Test
public void testThenAcceptBoth() throws ExecutionException, InterruptedException {
    CompletableFuture completableFuture1 = CompletableFuture.supplyAsync(() -> {
        log.info("任务 1 执行中...");
        return 10;
    });

    CompletableFuture completableFuture2 = CompletableFuture.supplyAsync(() -> {
        log.info("任务 2 执行中...");
        return 20;
    });

    CompletableFuture completableFuture3 = completableFuture1.thenAcceptBoth(completableFuture2, (result1, result2) -> {
        log.info("回调函数获取到 任务 1 结果：" + result1 + "，获取到任务 2 结果：" + result2);
        log.info("回调函数执行中...");
    });

    log.info("任务 1 返回结果：" + completableFuture1.get());
    log.info("任务 2 返回结果：" + completableFuture2.get());
    log.info("回调函数返回结果：" + completableFuture3.get());
}

控制台输出：

21:31:14.624 [ForkJoinPool.commonPool-worker-1] INFO com.c3stones.test.CompletableFutureTest - 任务 1 执行中...
21:31:14.624 [ForkJoinPool.commonPool-worker-2] INFO com.c3stones.test.CompletableFutureTest - 任务 2 执行中...
21:31:14.630 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 1 返回结果：10
21:31:14.630 [ForkJoinPool.commonPool-worker-2] INFO com.c3stones.test.CompletableFutureTest - 回调函数获取到 任务 1 结果：10，获取到任务 2 结果：20
21:31:14.630 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 2 返回结果：20
21:31:14.630 [ForkJoinPool.commonPool-worker-2] INFO com.c3stones.test.CompletableFutureTest - 回调函数执行中...
21:31:14.630 [main] INFO com.c3stones.test.CompletableFutureTest - 回调函数返回结果：null

/**
 * 任务1执行成功，任务2执行失败，再执行回调函数

 * 回调函数入参为任务1和任务2的返回结果，无返回值
 * 
 * 回调函数公用两个任务其中一个线程执行
 * 
 */
@Test
public void testThenAcceptBothException() throws ExecutionException, InterruptedException {
    CompletableFuture completableFuture1 = CompletableFuture.supplyAsync(() -> {
        log.info("任务 1 执行中...");
        return 10;
    });

    CompletableFuture completableFuture2 = CompletableFuture.supplyAsync(() -> {
        log.info("任务 2 执行中...");
        int a = 1 / 0;
        return 20;
    });

    CompletableFuture completableFuture3 = completableFuture1.thenAcceptBoth(completableFuture2, (result1, result2) -> {
        log.info("回调函数获取到 任务 1 结果：" + result1 + "，获取到任务 2 结果：" + result2);
        log.info("回调函数执行中...");
    });

    log.info("任务 1 返回结果：" + completableFuture1.get());
    log.info("任务 2 返回结果：" + completableFuture2.get());
    log.info("回调函数返回结果：" + completableFuture3.get());
}

控制台输出：

21:33:23.532 [ForkJoinPool.commonPool-worker-2] INFO com.c3stones.test.CompletableFutureTest - 任务 2 执行中...
21:33:23.527 [ForkJoinPool.commonPool-worker-1] INFO com.c3stones.test.CompletableFutureTest - 任务 1 执行中...
21:33:23.539 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 1 返回结果：10

java.util.concurrent.ExecutionException: java.lang.ArithmeticException: / by zero

	at java.util.concurrent.CompletableFuture.reportGet(CompletableFuture.java:357)
	at java.util.concurrent.CompletableFuture.get(CompletableFuture.java:1895)
	at com.c3stones.test.CompletableFutureTest.testThenAcceptBothException(CompletableFutureTest.java:619)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.platform.commons.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:725)
	at org.junit.jupiter.engine.execution.MethodInvocation.proceed(MethodInvocation.java:60)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain$ValidatingInvocation.proceed(InvocationInterceptorChain.java:131)
	at org.junit.jupiter.engine.extension.TimeoutExtension.intercept(TimeoutExtension.java:149)
	at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestableMethod(TimeoutExtension.java:140)
	at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestMethod(TimeoutExtension.java:84)
	at org.junit.jupiter.engine.execution.ExecutableInvoker$ReflectiveInterceptorCall.lambda$ofVoidMethod$0(ExecutableInvoker.java:115)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.lambda$invoke$0(ExecutableInvoker.java:105)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain$InterceptedInvocation.proceed(InvocationInterceptorChain.java:106)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.proceed(InvocationInterceptorChain.java:64)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.chainAndInvoke(InvocationInterceptorChain.java:45)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.invoke(InvocationInterceptorChain.java:37)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:104)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:98)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$invokeTestMethod$7(TestMethodTestDescriptor.java:214)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.invokeTestMethod(TestMethodTestDescriptor.java:210)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:135)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:66)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:151)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at java.util.ArrayList.forEach(ArrayList.java:1249)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at java.util.ArrayList.forEach(ArrayList.java:1249)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:35)
	at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:57)
	at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:54)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:107)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:88)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.lambda$execute$0(EngineExecutionOrchestrator.java:54)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.withInterceptedStreams(EngineExecutionOrchestrator.java:67)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:52)
	at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:114)
	at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:86)
	at org.junit.platform.launcher.core.DefaultLauncherSession$DelegatingLauncher.execute(DefaultLauncherSession.java:86)
	at org.junit.platform.launcher.core.SessionPerRequestLauncher.execute(SessionPerRequestLauncher.java:53)
	at com.intellij.junit5.JUnit5IdeaTestRunner.startRunnerWithArgs(JUnit5IdeaTestRunner.java:71)
	at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
	at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:235)
	at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:54)
Caused by: java.lang.ArithmeticException: / by zero
	at com.c3stones.test.CompletableFutureTest.lambda$testThenAcceptBothException$48(CompletableFutureTest.java:609)
	at java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1590)
	at java.util.concurrent.CompletableFuture$AsyncSupply.exec(CompletableFuture.java:1582)
	at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:289)
	at java.util.concurrent.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1056)
	at java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1692)
	at java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:157)

thenAcceptBothAsync

/**
 * 任务1和任务2都执行成功，再执行回调函数

 * 回调函数入参为任务1和任务2的返回结果，无返回值
 * 
 * 提交给线程池，不同线程执行
 * 
 */
@Test
public void testThenAcceptBothAsync() throws ExecutionException, InterruptedException {
    ExecutorService executorService = Executors.newCachedThreadPool();

    CompletableFuture completableFuture1 = CompletableFuture.supplyAsync(() -> {
        log.info("任务 1 执行中...");
        return 10;
    }, executorService);

    CompletableFuture completableFuture2 = CompletableFuture.supplyAsync(() -> {
        log.info("任务 2 执行中...");
        return 20;
    }, executorService);

    CompletableFuture completableFuture3 = completableFuture1.thenAcceptBothAsync(completableFuture2, (result1, result2) -> {
        log.info("回调函数获取到 任务 1 结果：" + result1 + "，获取到任务 2 结果：" + result2);
        log.info("回调函数执行中...");
    }, executorService);

    log.info("任务 1 返回结果：" + completableFuture1.get());
    log.info("任务 2 返回结果：" + completableFuture2.get());
    log.info("回调函数返回结果：" + completableFuture3.get());
}

控制台输出：

21:34:44.099 [pool-1-thread-2] INFO com.c3stones.test.CompletableFutureTest - 任务 2 执行中...
21:34:44.099 [pool-1-thread-1] INFO com.c3stones.test.CompletableFutureTest - 任务 1 执行中...
21:34:44.105 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 1 返回结果：10
21:34:44.106 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 2 返回结果：20
21:34:44.106 [pool-1-thread-3] INFO com.c3stones.test.CompletableFutureTest - 回调函数获取到 任务 1 结果：10，获取到任务 2 结果：20
21:34:44.106 [pool-1-thread-3] INFO com.c3stones.test.CompletableFutureTest - 回调函数执行中...
21:34:44.106 [main] INFO com.c3stones.test.CompletableFutureTest - 回调函数返回结果：null

/**
 * 任务1执行成功，任务2执行失败，再执行回调函数

 * 回调函数入参为任务1和任务2的返回结果，无返回值
 * 
 * 提交给线程池，不同线程执行
 * 
 */
@Test
public void testThenAcceptBothAsyncException() throws ExecutionException, InterruptedException {
    ExecutorService executorService = Executors.newCachedThreadPool();

    CompletableFuture completableFuture1 = CompletableFuture.supplyAsync(() -> {
        log.info("任务 1 执行中...");
        return 10;
    }, executorService);

    CompletableFuture completableFuture2 = CompletableFuture.supplyAsync(() -> {
        log.info("任务 2 执行中...");
        int a = 1 / 0;
        return 20;
    }, executorService);

    CompletableFuture completableFuture3 = completableFuture1.thenAcceptBothAsync(completableFuture2, (result1, result2) -> {
        log.info("回调函数获取到 任务 1 结果：" + result1 + "，获取到任务 2 结果：" + result2);
        log.info("回调函数执行中...");
    }, executorService);

    log.info("任务 1 返回结果：" + completableFuture1.get());
    log.info("任务 2 返回结果：" + completableFuture2.get());
    log.info("回调函数返回结果：" + completableFuture3.get());
}

控制台输出：

21:35:31.832 [pool-1-thread-1] INFO com.c3stones.test.CompletableFutureTest - 任务 1 执行中...
21:35:31.833 [pool-1-thread-2] INFO com.c3stones.test.CompletableFutureTest - 任务 2 执行中...
21:35:31.839 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 1 返回结果：10

java.util.concurrent.ExecutionException: java.lang.ArithmeticException: / by zero

	at java.util.concurrent.CompletableFuture.reportGet(CompletableFuture.java:357)
	at java.util.concurrent.CompletableFuture.get(CompletableFuture.java:1895)
	at com.c3stones.test.CompletableFutureTest.testThenAcceptBothAsyncException(CompletableFutureTest.java:682)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.platform.commons.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:725)
	at org.junit.jupiter.engine.execution.MethodInvocation.proceed(MethodInvocation.java:60)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain$ValidatingInvocation.proceed(InvocationInterceptorChain.java:131)
	at org.junit.jupiter.engine.extension.TimeoutExtension.intercept(TimeoutExtension.java:149)
	at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestableMethod(TimeoutExtension.java:140)
	at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestMethod(TimeoutExtension.java:84)
	at org.junit.jupiter.engine.execution.ExecutableInvoker$ReflectiveInterceptorCall.lambda$ofVoidMethod$0(ExecutableInvoker.java:115)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.lambda$invoke$0(ExecutableInvoker.java:105)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain$InterceptedInvocation.proceed(InvocationInterceptorChain.java:106)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.proceed(InvocationInterceptorChain.java:64)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.chainAndInvoke(InvocationInterceptorChain.java:45)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.invoke(InvocationInterceptorChain.java:37)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:104)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:98)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$invokeTestMethod$7(TestMethodTestDescriptor.java:214)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.invokeTestMethod(TestMethodTestDescriptor.java:210)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:135)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:66)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:151)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at java.util.ArrayList.forEach(ArrayList.java:1249)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at java.util.ArrayList.forEach(ArrayList.java:1249)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:35)
	at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:57)
	at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:54)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:107)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:88)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.lambda$execute$0(EngineExecutionOrchestrator.java:54)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.withInterceptedStreams(EngineExecutionOrchestrator.java:67)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:52)
	at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:114)
	at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:86)
	at org.junit.platform.launcher.core.DefaultLauncherSession$DelegatingLauncher.execute(DefaultLauncherSession.java:86)
	at org.junit.platform.launcher.core.SessionPerRequestLauncher.execute(SessionPerRequestLauncher.java:53)
	at com.intellij.junit5.JUnit5IdeaTestRunner.startRunnerWithArgs(JUnit5IdeaTestRunner.java:71)
	at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
	at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:235)
	at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:54)
Caused by: java.lang.ArithmeticException: / by zero
	at com.c3stones.test.CompletableFutureTest.lambda$testThenAcceptBothAsyncException$54(CompletableFutureTest.java:672)
	at java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1590)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at java.lang.Thread.run(Thread.java:745)

3.3.3 runAfterBoth/runAfterBothAsync

runAfterBoth和runAfterBothAsync都是将两个异步任务组合后处理。当两个任务都执行完成后，执行回调函数。回调函数无入参，也无返回值。如果两个任务有一个执行异常，则抛出异常。区别在于：runAfterBoth执行回调函数时会公用执行两个任务的其中一个的线程，而runAfterBothAsync会使用不同的线程，并且runAfterBothAsync支持指定线程池。

runAfterBoth

/**
 * 任务1和任务2都执行成功，再执行回调函数

 * 回调函数无入参，无返回值
 * 
 * 回调函数公用两个任务其中一个线程执行
 * 
 */
@Test
public void testRunAfterBoth() throws ExecutionException, InterruptedException {
    CompletableFuture completableFuture1 = CompletableFuture.supplyAsync(() -> {
        log.info("任务 1 执行中...");
        return 10;
    });

    CompletableFuture completableFuture2 = CompletableFuture.supplyAsync(() -> {
        log.info("任务 2 执行中...");
        return 20;
    });

    CompletableFuture completableFuture3 = completableFuture1.runAfterBoth(completableFuture2, () -> {
        log.info("回调函数执行中...");
    });

    log.info("任务 1 返回结果：" + completableFuture1.get());
    log.info("任务 2 返回结果：" + completableFuture2.get());
    log.info("回调函数返回结果：" + completableFuture3.get());
}

控制台输出：

21:39:33.677 [ForkJoinPool.commonPool-worker-1] INFO com.c3stones.test.CompletableFutureTest - 任务 1 执行中...
21:39:33.683 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 1 返回结果：10
21:39:33.684 [ForkJoinPool.commonPool-worker-2] INFO com.c3stones.test.CompletableFutureTest - 任务 2 执行中...
21:39:33.684 [ForkJoinPool.commonPool-worker-2] INFO com.c3stones.test.CompletableFutureTest - 回调函数执行中...
21:39:33.684 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 2 返回结果：20
21:39:33.684 [main] INFO com.c3stones.test.CompletableFutureTest - 回调函数返回结果：null

/**
 * 任务1执行成功，任务2执行失败，再执行回调函数

 * 回调函数无入参，无返回值
 * 
 * 回调函数公用两个任务其中一个线程执行
 * 
 */
@Test
public void testRunAfterBothException() throws ExecutionException, InterruptedException {
    CompletableFuture completableFuture1 = CompletableFuture.supplyAsync(() -> {
        log.info("任务 1 执行中...");
        return 10;
    });

    CompletableFuture completableFuture2 = CompletableFuture.supplyAsync(() -> {
        log.info("任务 2 执行中...");
        int a = 1 / 0;
        return 20;
    });

    CompletableFuture completableFuture3 = completableFuture1.runAfterBoth(completableFuture2, () -> {
        log.info("回调函数执行中...");
    });

    log.info("任务 1 返回结果：" + completableFuture1.get());
    log.info("任务 2 返回结果：" + completableFuture2.get());
    log.info("回调函数返回结果：" + completableFuture3.get());
}

控制台输出：

21:40:44.127 [ForkJoinPool.commonPool-worker-2] INFO com.c3stones.test.CompletableFutureTest - 任务 2 执行中...
21:40:44.128 [ForkJoinPool.commonPool-worker-1] INFO com.c3stones.test.CompletableFutureTest - 任务 1 执行中...
21:40:44.136 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 1 返回结果：10

java.util.concurrent.ExecutionException: java.lang.ArithmeticException: / by zero

	at java.util.concurrent.CompletableFuture.reportGet(CompletableFuture.java:357)
	at java.util.concurrent.CompletableFuture.get(CompletableFuture.java:1895)
	at com.c3stones.test.CompletableFutureTest.testRunAfterBothException(CompletableFutureTest.java:739)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.platform.commons.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:725)
	at org.junit.jupiter.engine.execution.MethodInvocation.proceed(MethodInvocation.java:60)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain$ValidatingInvocation.proceed(InvocationInterceptorChain.java:131)
	at org.junit.jupiter.engine.extension.TimeoutExtension.intercept(TimeoutExtension.java:149)
	at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestableMethod(TimeoutExtension.java:140)
	at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestMethod(TimeoutExtension.java:84)
	at org.junit.jupiter.engine.execution.ExecutableInvoker$ReflectiveInterceptorCall.lambda$ofVoidMethod$0(ExecutableInvoker.java:115)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.lambda$invoke$0(ExecutableInvoker.java:105)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain$InterceptedInvocation.proceed(InvocationInterceptorChain.java:106)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.proceed(InvocationInterceptorChain.java:64)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.chainAndInvoke(InvocationInterceptorChain.java:45)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.invoke(InvocationInterceptorChain.java:37)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:104)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:98)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$invokeTestMethod$7(TestMethodTestDescriptor.java:214)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.invokeTestMethod(TestMethodTestDescriptor.java:210)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:135)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:66)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:151)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at java.util.ArrayList.forEach(ArrayList.java:1249)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at java.util.ArrayList.forEach(ArrayList.java:1249)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:35)
	at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:57)
	at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:54)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:107)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:88)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.lambda$execute$0(EngineExecutionOrchestrator.java:54)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.withInterceptedStreams(EngineExecutionOrchestrator.java:67)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:52)
	at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:114)
	at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:86)
	at org.junit.platform.launcher.core.DefaultLauncherSession$DelegatingLauncher.execute(DefaultLauncherSession.java:86)
	at org.junit.platform.launcher.core.SessionPerRequestLauncher.execute(SessionPerRequestLauncher.java:53)
	at com.intellij.junit5.JUnit5IdeaTestRunner.startRunnerWithArgs(JUnit5IdeaTestRunner.java:71)
	at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
	at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:235)
	at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:54)
Caused by: java.lang.ArithmeticException: / by zero
	at com.c3stones.test.CompletableFutureTest.lambda$testRunAfterBothException$60(CompletableFutureTest.java:730)
	at java.util.concurrent.CompletableFuture$AsyncSupply.run$$$capture(CompletableFuture.java:1590)
	at java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java)
	at java.util.concurrent.CompletableFuture$AsyncSupply.exec(CompletableFuture.java:1582)
	at java.util.concurrent.ForkJoinTask.doExec$$$capture(ForkJoinTask.java:289)
	at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java)
	at java.util.concurrent.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1056)
	at java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1692)
	at java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:157)

runAfterBothAsync

/**
 * 任务1和任务2都执行成功，再执行回调函数

 * 回调函数无入参，无返回值
 * 
 * 提交给线程池，不同线程执行
 * 
 */
@Test
public void testRunAfterBothAsync() throws ExecutionException, InterruptedException {
	ExecutorService executorService = Executors.newCachedThreadPool();

	CompletableFuture completableFuture1 = CompletableFuture.supplyAsync(() -> {
		log.info("任务 1 执行中...");
		return 10;
	}, executorService);

	CompletableFuture completableFuture2 = CompletableFuture.supplyAsync(() -> {
		log.info("任务 2 执行中...");
		return 20;
	}, executorService);

	CompletableFuture completableFuture3 = completableFuture1.runAfterBothAsync(completableFuture2, () -> {
		log.info("回调函数执行中...");
	}, executorService);

	log.info("任务 1 返回结果：" + completableFuture1.get());
	log.info("任务 2 返回结果：" + completableFuture2.get());
	log.info("回调函数返回结果：" + completableFuture3.get());
}

控制台输出：

21:42:19.533 [pool-1-thread-2] INFO com.c3stones.test.CompletableFutureTest - 任务 2 执行中...
21:42:19.533 [pool-1-thread-1] INFO com.c3stones.test.CompletableFutureTest - 任务 1 执行中...
21:42:19.539 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 1 返回结果：10
21:42:19.540 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 2 返回结果：20
21:42:19.546 [pool-1-thread-3] INFO com.c3stones.test.CompletableFutureTest - 回调函数执行中...
21:42:19.546 [main] INFO com.c3stones.test.CompletableFutureTest - 回调函数返回结果：null

/**
 * 任务1执行成功，任务2执行失败，再执行回调函数

 * 回调函数无入参，无返回值
 * 
 * 提交给线程池，不同线程执行
 * 
 */
@Test
public void testRunAfterBothAsyncException() throws ExecutionException, InterruptedException {
	ExecutorService executorService = Executors.newCachedThreadPool();

	CompletableFuture completableFuture1 = CompletableFuture.supplyAsync(() -> {
		log.info("任务 1 执行中...");
		return 10;
	}, executorService);

	CompletableFuture completableFuture2 = CompletableFuture.supplyAsync(() -> {
		log.info("任务 2 执行中...");
		int a = 1 / 0;
		return 20;
	}, executorService);

	CompletableFuture completableFuture3 = completableFuture1.runAfterBothAsync(completableFuture2, () -> {
		log.info("回调函数执行中...");
	}, executorService);

	log.info("任务 1 返回结果：" + completableFuture1.get());
	log.info("任务 2 返回结果：" + completableFuture2.get());
	log.info("回调函数返回结果：" + completableFuture3.get());
}

控制台输出：

21:43:36.457 [pool-1-thread-2] INFO com.c3stones.test.CompletableFutureTest - 任务 2 执行中...
21:43:36.464 [pool-1-thread-1] INFO com.c3stones.test.CompletableFutureTest - 任务 1 执行中...
21:43:36.464 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 1 返回结果：10

java.util.concurrent.ExecutionException: java.lang.ArithmeticException: / by zero

	at java.util.concurrent.CompletableFuture.reportGet(CompletableFuture.java:357)
	at java.util.concurrent.CompletableFuture.get(CompletableFuture.java:1895)
	at com.c3stones.test.CompletableFutureTest.testRunAfterBothAsyncException(CompletableFutureTest.java:800)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.platform.commons.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:725)
	at org.junit.jupiter.engine.execution.MethodInvocation.proceed(MethodInvocation.java:60)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain$ValidatingInvocation.proceed(InvocationInterceptorChain.java:131)
	at org.junit.jupiter.engine.extension.TimeoutExtension.intercept(TimeoutExtension.java:149)
	at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestableMethod(TimeoutExtension.java:140)
	at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestMethod(TimeoutExtension.java:84)
	at org.junit.jupiter.engine.execution.ExecutableInvoker$ReflectiveInterceptorCall.lambda$ofVoidMethod$0(ExecutableInvoker.java:115)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.lambda$invoke$0(ExecutableInvoker.java:105)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain$InterceptedInvocation.proceed(InvocationInterceptorChain.java:106)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.proceed(InvocationInterceptorChain.java:64)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.chainAndInvoke(InvocationInterceptorChain.java:45)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.invoke(InvocationInterceptorChain.java:37)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:104)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:98)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$invokeTestMethod$7(TestMethodTestDescriptor.java:214)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.invokeTestMethod(TestMethodTestDescriptor.java:210)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:135)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:66)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:151)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at java.util.ArrayList.forEach(ArrayList.java:1249)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at java.util.ArrayList.forEach(ArrayList.java:1249)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:35)
	at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:57)
	at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:54)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:107)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:88)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.lambda$execute$0(EngineExecutionOrchestrator.java:54)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.withInterceptedStreams(EngineExecutionOrchestrator.java:67)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:52)
	at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:114)
	at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:86)
	at org.junit.platform.launcher.core.DefaultLauncherSession$DelegatingLauncher.execute(DefaultLauncherSession.java:86)
	at org.junit.platform.launcher.core.SessionPerRequestLauncher.execute(SessionPerRequestLauncher.java:53)
	at com.intellij.junit5.JUnit5IdeaTestRunner.startRunnerWithArgs(JUnit5IdeaTestRunner.java:71)
	at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
	at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:235)
	at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:54)
Caused by: java.lang.ArithmeticException: / by zero
	at com.c3stones.test.CompletableFutureTest.lambda$testRunAfterBothAsyncException$66(CompletableFutureTest.java:791)
	at java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1590)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at java.lang.Thread.run(Thread.java:745)

3.3.4 applyToEither/applyToEitherAsync

applyToEither和applyToEitherAsync都是将两个异步任务组合后处理。回调函数会将第一个完成的任务的返回结果作为入参，并带有返回值。如果两个任务有一个执行异常，则抛出异常。区别在于：applyToEither执行回调函数时会公用第一个完成的任务的线程，而applyToEitherAsync会使用不同的线程，并且applyToEitherAsync支持指定线程池。

applyToEither

/**
 * 任务1或任务2执行成功，再执行回调函数

 * 回调函数入参为第一个完成的任务的返回结果，并带有返回值
 * 
 * 回调函数和第一个完成的任务使用相同线程执行
 * 
 */
@Test
public void testApplyToEither() throws ExecutionException, InterruptedException {
	CompletableFuture completableFuture1 = CompletableFuture.supplyAsync(() -> {
		log.info("任务 1 执行中...");
		try {
			TimeUnit.SECONDS.sleep(1);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		return 10;
	});

	CompletableFuture completableFuture2 = CompletableFuture.supplyAsync(() -> {
		log.info("任务 2 执行中...");
		try {
			TimeUnit.SECONDS.sleep(2);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		return 20;
	});

	CompletableFuture completableFuture3 = completableFuture1.applyToEither(completableFuture2, (result) -> {
		log.info("回调函数获取到结果：" + result);
		log.info("回调函数执行中...");
		return result * 10;
	});

	log.info("任务 1 返回结果：" + completableFuture1.get());
	log.info("任务 2 返回结果：" + completableFuture2.get());
	log.info("回调函数返回结果：" + completableFuture3.get());
}

控制台输出：

22:08:52.369 [ForkJoinPool.commonPool-worker-1] INFO com.c3stones.test.CompletableFutureTest - 任务 1 执行中...
22:08:52.371 [ForkJoinPool.commonPool-worker-2] INFO com.c3stones.test.CompletableFutureTest - 任务 2 执行中...
22:08:53.376 [main] INFO com.c3stones.test.CompletableFutureTest - 回调函数获取到结果：10
22:08:53.376 [main] INFO com.c3stones.test.CompletableFutureTest - 回调函数执行中...
22:08:53.376 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 1 返回结果：10
22:08:54.378 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 2 返回结果：20
22:08:54.379 [main] INFO com.c3stones.test.CompletableFutureTest - 回调函数返回结果：100

/**
 * 任务1执行成功，任务2执行失败，再执行回调函数

 * 回调函数入参为第一个完成的任务的返回结果，并带有返回值
 * 
 * 回调函数和第一个完成的任务使用相同线程执行
 * 
 */
@Test
public void testApplyToEitherException() throws ExecutionException, InterruptedException {
	CompletableFuture completableFuture1 = CompletableFuture.supplyAsync(() -> {
		log.info("任务 1 执行中...");
		try {
			TimeUnit.SECONDS.sleep(1);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		return 10;
	});

	CompletableFuture completableFuture2 = CompletableFuture.supplyAsync(() -> {
		log.info("任务 2 执行中...");
		try {
			TimeUnit.SECONDS.sleep(2);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		int a = 1 / 0;
		return 20;
	});

	CompletableFuture completableFuture3 = completableFuture1.applyToEither(completableFuture2, (result) -> {
		log.info("回调函数获取到结果：" + result);
		log.info("回调函数执行中...");
		return result * 10;
	});

	log.info("任务 1 返回结果：" + completableFuture1.get());
	log.info("任务 2 返回结果：" + completableFuture2.get());
	log.info("回调函数返回结果：" + completableFuture3.get());
}

控制台输出：

22:11:25.616 [ForkJoinPool.commonPool-worker-1] INFO com.c3stones.test.CompletableFutureTest - 任务 1 执行中...
22:11:25.616 [ForkJoinPool.commonPool-worker-2] INFO com.c3stones.test.CompletableFutureTest - 任务 2 执行中...
22:11:26.621 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 1 返回结果：10
22:11:26.621 [ForkJoinPool.commonPool-worker-1] INFO com.c3stones.test.CompletableFutureTest - 回调函数获取到结果：10
22:11:26.621 [ForkJoinPool.commonPool-worker-1] INFO com.c3stones.test.CompletableFutureTest - 回调函数执行中...

java.util.concurrent.ExecutionException: java.lang.ArithmeticException: / by zero

	at java.util.concurrent.CompletableFuture.reportGet(CompletableFuture.java:357)
	at java.util.concurrent.CompletableFuture.get(CompletableFuture.java:1895)
	at com.c3stones.test.CompletableFutureTest.testApplyToEitherException(CompletableFutureTest.java:881)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.platform.commons.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:725)
	at org.junit.jupiter.engine.execution.MethodInvocation.proceed(MethodInvocation.java:60)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain$ValidatingInvocation.proceed(InvocationInterceptorChain.java:131)
	at org.junit.jupiter.engine.extension.TimeoutExtension.intercept(TimeoutExtension.java:149)
	at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestableMethod(TimeoutExtension.java:140)
	at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestMethod(TimeoutExtension.java:84)
	at org.junit.jupiter.engine.execution.ExecutableInvoker$ReflectiveInterceptorCall.lambda$ofVoidMethod$0(ExecutableInvoker.java:115)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.lambda$invoke$0(ExecutableInvoker.java:105)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain$InterceptedInvocation.proceed(InvocationInterceptorChain.java:106)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.proceed(InvocationInterceptorChain.java:64)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.chainAndInvoke(InvocationInterceptorChain.java:45)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.invoke(InvocationInterceptorChain.java:37)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:104)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:98)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$invokeTestMethod$7(TestMethodTestDescriptor.java:214)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.invokeTestMethod(TestMethodTestDescriptor.java:210)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:135)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:66)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:151)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at java.util.ArrayList.forEach(ArrayList.java:1249)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at java.util.ArrayList.forEach(ArrayList.java:1249)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:35)
	at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:57)
	at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:54)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:107)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:88)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.lambda$execute$0(EngineExecutionOrchestrator.java:54)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.withInterceptedStreams(EngineExecutionOrchestrator.java:67)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:52)
	at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:114)
	at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:86)
	at org.junit.platform.launcher.core.DefaultLauncherSession$DelegatingLauncher.execute(DefaultLauncherSession.java:86)
	at org.junit.platform.launcher.core.SessionPerRequestLauncher.execute(SessionPerRequestLauncher.java:53)
	at com.intellij.junit5.JUnit5IdeaTestRunner.startRunnerWithArgs(JUnit5IdeaTestRunner.java:71)
	at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
	at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:235)
	at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:54)
Caused by: java.lang.ArithmeticException: / by zero
	at com.c3stones.test.CompletableFutureTest.lambda$testApplyToEitherException$72(CompletableFutureTest.java:870)
	at java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1590)
	at java.util.concurrent.CompletableFuture$AsyncSupply.exec(CompletableFuture.java:1582)
	at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:289)
	at java.util.concurrent.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1056)
	at java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1692)
	at java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:157)

applyToEitherAsync

/**
 * 任务1或任务2执行成功，再执行回调函数

 * 回调函数入参为第一个完成的任务的返回结果，并带有返回值
 * 
 * 提交给线程池，不同线程执行
 * 
 */
@Test
public void testApplyToEitherAsync() throws ExecutionException, InterruptedException {
	ExecutorService executorService = Executors.newCachedThreadPool();

	CompletableFuture completableFuture1 = CompletableFuture.supplyAsync(() -> {
		log.info("任务 1 执行中...");
		try {
			TimeUnit.SECONDS.sleep(1);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		return 10;
	}, executorService);

	CompletableFuture completableFuture2 = CompletableFuture.supplyAsync(() -> {
		log.info("任务 2 执行中...");
		try {
			TimeUnit.SECONDS.sleep(2);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		return 20;
	}, executorService);

	CompletableFuture completableFuture3 = completableFuture1.applyToEitherAsync(completableFuture2, (result) -> {
		log.info("回调函数获取到结果：" + result);
		log.info("回调函数执行中...");
		return result * 10;
	}, executorService);

	log.info("任务 1 返回结果：" + completableFuture1.get());
	log.info("任务 2 返回结果：" + completableFuture2.get());
	log.info("回调函数返回结果：" + completableFuture3.get());
}

控制台输出：

22:12:08.089 [pool-1-thread-2] INFO com.c3stones.test.CompletableFutureTest - 任务 2 执行中...
22:12:08.089 [pool-1-thread-1] INFO com.c3stones.test.CompletableFutureTest - 任务 1 执行中...
22:12:09.096 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 1 返回结果：10
22:12:09.096 [pool-1-thread-3] INFO com.c3stones.test.CompletableFutureTest - 回调函数获取到结果：10
22:12:09.096 [pool-1-thread-3] INFO com.c3stones.test.CompletableFutureTest - 回调函数执行中...
22:12:10.096 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 2 返回结果：20
22:12:10.096 [main] INFO com.c3stones.test.CompletableFutureTest - 回调函数返回结果：100

/**
 * 任务1执行成功，任务2执行失败，再执行回调函数

 * 回调函数入参为第一个完成的任务的返回结果，并带有返回值
 * 
 * 提交给线程池，不同线程执行
 * 
 */
@Test
public void testApplyToEitherAsyncException() throws ExecutionException, InterruptedException {
	ExecutorService executorService = Executors.newCachedThreadPool();

	CompletableFuture completableFuture1 = CompletableFuture.supplyAsync(() -> {
		log.info("任务 1 执行中...");
		try {
			TimeUnit.SECONDS.sleep(1);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		return 10;
	}, executorService);

	CompletableFuture completableFuture2 = CompletableFuture.supplyAsync(() -> {
		log.info("任务 2 执行中...");
		try {
			TimeUnit.SECONDS.sleep(2);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		int a = 1 / 0;
		return 20;
	}, executorService);

	CompletableFuture completableFuture3 = completableFuture1.applyToEitherAsync(completableFuture2, (result) -> {
		log.info("回调函数获取到结果：" + result);
		log.info("回调函数执行中...");
		return result * 10;
	}, executorService);

	log.info("任务 1 返回结果：" + completableFuture1.get());
	log.info("任务 2 返回结果：" + completableFuture2.get());
	log.info("回调函数返回结果：" + completableFuture3.get());
}

控制台输出：

22:12:40.922 [pool-1-thread-1] INFO com.c3stones.test.CompletableFutureTest - 任务 1 执行中...
22:12:40.928 [pool-1-thread-2] INFO com.c3stones.test.CompletableFutureTest - 任务 2 执行中...
22:12:41.928 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 1 返回结果：10
22:12:41.929 [pool-1-thread-3] INFO com.c3stones.test.CompletableFutureTest - 回调函数获取到结果：10
22:12:41.929 [pool-1-thread-3] INFO com.c3stones.test.CompletableFutureTest - 回调函数执行中...

java.util.concurrent.ExecutionException: java.lang.ArithmeticException: / by zero

	at java.util.concurrent.CompletableFuture.reportGet(CompletableFuture.java:357)
	at java.util.concurrent.CompletableFuture.get(CompletableFuture.java:1895)
	at com.c3stones.test.CompletableFutureTest.testApplyToEitherAsyncException(CompletableFutureTest.java:966)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.platform.commons.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:725)
	at org.junit.jupiter.engine.execution.MethodInvocation.proceed(MethodInvocation.java:60)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain$ValidatingInvocation.proceed(InvocationInterceptorChain.java:131)
	at org.junit.jupiter.engine.extension.TimeoutExtension.intercept(TimeoutExtension.java:149)
	at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestableMethod(TimeoutExtension.java:140)
	at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestMethod(TimeoutExtension.java:84)
	at org.junit.jupiter.engine.execution.ExecutableInvoker$ReflectiveInterceptorCall.lambda$ofVoidMethod$0(ExecutableInvoker.java:115)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.lambda$invoke$0(ExecutableInvoker.java:105)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain$InterceptedInvocation.proceed(InvocationInterceptorChain.java:106)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.proceed(InvocationInterceptorChain.java:64)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.chainAndInvoke(InvocationInterceptorChain.java:45)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.invoke(InvocationInterceptorChain.java:37)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:104)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:98)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$invokeTestMethod$7(TestMethodTestDescriptor.java:214)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.invokeTestMethod(TestMethodTestDescriptor.java:210)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:135)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:66)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:151)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at java.util.ArrayList.forEach(ArrayList.java:1249)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at java.util.ArrayList.forEach(ArrayList.java:1249)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:35)
	at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:57)
	at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:54)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:107)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:88)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.lambda$execute$0(EngineExecutionOrchestrator.java:54)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.withInterceptedStreams(EngineExecutionOrchestrator.java:67)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:52)
	at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:114)
	at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:86)
	at org.junit.platform.launcher.core.DefaultLauncherSession$DelegatingLauncher.execute(DefaultLauncherSession.java:86)
	at org.junit.platform.launcher.core.SessionPerRequestLauncher.execute(SessionPerRequestLauncher.java:53)
	at com.intellij.junit5.JUnit5IdeaTestRunner.startRunnerWithArgs(JUnit5IdeaTestRunner.java:71)
	at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
	at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:235)
	at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:54)
Caused by: java.lang.ArithmeticException: / by zero
	at com.c3stones.test.CompletableFutureTest.lambda$testApplyToEitherAsyncException$78(CompletableFutureTest.java:955)
	at java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1590)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at java.lang.Thread.run(Thread.java:745)

3.3.5 acceptEither/acceptEitherAsync

acceptEither和acceptEitherAsync都是将两个异步任务组合后处理。回调函数会将第一个完成的任务的返回结果作为入参，但无返回值。如果两个任务有一个执行异常，则抛出异常。区别在于：acceptEither执行回调函数时会公用第一个完成的任务的线程，而acceptEitherAsync会使用不同的线程，并且acceptEitherAsync支持指定线程池。

acceptEither

/**
 * 任务1或任务2执行成功，再执行回调函数

 * 回调函数入参为第一个完成的任务的返回结果，无返回值
 * 
 * 回调函数和第一个完成的任务使用相同线程执行
 * 
 */
@Test
public void testAcceptEither() throws ExecutionException, InterruptedException {
	CompletableFuture completableFuture1 = CompletableFuture.supplyAsync(() -> {
		log.info("任务 1 执行中...");
		try {
			TimeUnit.SECONDS.sleep(1);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		return 10;
	});

	CompletableFuture completableFuture2 = CompletableFuture.supplyAsync(() -> {
		log.info("任务 2 执行中...");
		try {
			TimeUnit.SECONDS.sleep(2);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		return 20;
	});

	CompletableFuture completableFuture3 = completableFuture1.acceptEither(completableFuture2, (result) -> {
		log.info("回调函数获取到结果：" + result);
		log.info("回调函数执行中...");
	});

	log.info("任务 1 返回结果：" + completableFuture1.get());
	log.info("任务 2 返回结果：" + completableFuture2.get());
	log.info("回调函数返回结果：" + completableFuture3.get());
}

控制台输出：

22:15:07.135 [ForkJoinPool.commonPool-worker-1] INFO com.c3stones.test.CompletableFutureTest - 任务 1 执行中...
22:15:07.135 [ForkJoinPool.commonPool-worker-2] INFO com.c3stones.test.CompletableFutureTest - 任务 2 执行中...
22:15:08.141 [ForkJoinPool.commonPool-worker-1] INFO com.c3stones.test.CompletableFutureTest - 回调函数获取到结果：10
22:15:08.141 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 1 返回结果：10
22:15:08.141 [ForkJoinPool.commonPool-worker-1] INFO com.c3stones.test.CompletableFutureTest - 回调函数执行中...
22:15:09.141 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 2 返回结果：20
22:15:09.141 [main] INFO com.c3stones.test.CompletableFutureTest - 回调函数返回结果：null

/**
 * 任务1执行成功，任务2执行失败，再执行回调函数

 * 回调函数入参为第一个完成的任务的返回结果，无返回值
 * 
 * 回调函数和第一个完成的任务使用相同线程执行
 * 
 */
@Test
public void testAcceptEitherException() throws ExecutionException, InterruptedException {
	CompletableFuture completableFuture1 = CompletableFuture.supplyAsync(() -> {
		log.info("任务 1 执行中...");
		try {
			TimeUnit.SECONDS.sleep(1);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		return 10;
	});

	CompletableFuture completableFuture2 = CompletableFuture.supplyAsync(() -> {
		log.info("任务 2 执行中...");
		try {
			TimeUnit.SECONDS.sleep(2);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		int a = 1 / 0;
		return 20;
	});

	CompletableFuture completableFuture3 = completableFuture1.acceptEither(completableFuture2, (result) -> {
		log.info("回调函数获取到结果：" + result);
		log.info("回调函数执行中...");
	});

	log.info("任务 1 返回结果：" + completableFuture1.get());
	log.info("任务 2 返回结果：" + completableFuture2.get());
	log.info("回调函数返回结果：" + completableFuture3.get());
}

控制台输出：

22:18:56.628 [ForkJoinPool.commonPool-worker-1] INFO com.c3stones.test.CompletableFutureTest - 任务 1 执行中...
22:18:56.628 [ForkJoinPool.commonPool-worker-2] INFO com.c3stones.test.CompletableFutureTest - 任务 2 执行中...
22:18:57.633 [ForkJoinPool.commonPool-worker-1] INFO com.c3stones.test.CompletableFutureTest - 回调函数获取到结果：10
22:18:57.633 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 1 返回结果：10
22:18:57.633 [ForkJoinPool.commonPool-worker-1] INFO com.c3stones.test.CompletableFutureTest - 回调函数执行中...

java.util.concurrent.ExecutionException: java.lang.ArithmeticException: / by zero

	at java.util.concurrent.CompletableFuture.reportGet(CompletableFuture.java:357)
	at java.util.concurrent.CompletableFuture.get(CompletableFuture.java:1895)
	at com.c3stones.test.CompletableFutureTest.testAcceptEitherException(CompletableFutureTest.java:1045)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.platform.commons.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:725)
	at org.junit.jupiter.engine.execution.MethodInvocation.proceed(MethodInvocation.java:60)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain$ValidatingInvocation.proceed(InvocationInterceptorChain.java:131)
	at org.junit.jupiter.engine.extension.TimeoutExtension.intercept(TimeoutExtension.java:149)
	at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestableMethod(TimeoutExtension.java:140)
	at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestMethod(TimeoutExtension.java:84)
	at org.junit.jupiter.engine.execution.ExecutableInvoker$ReflectiveInterceptorCall.lambda$ofVoidMethod$0(ExecutableInvoker.java:115)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.lambda$invoke$0(ExecutableInvoker.java:105)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain$InterceptedInvocation.proceed(InvocationInterceptorChain.java:106)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.proceed(InvocationInterceptorChain.java:64)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.chainAndInvoke(InvocationInterceptorChain.java:45)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.invoke(InvocationInterceptorChain.java:37)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:104)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:98)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$invokeTestMethod$7(TestMethodTestDescriptor.java:214)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.invokeTestMethod(TestMethodTestDescriptor.java:210)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:135)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:66)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:151)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at java.util.ArrayList.forEach(ArrayList.java:1249)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at java.util.ArrayList.forEach(ArrayList.java:1249)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:35)
	at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:57)
	at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:54)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:107)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:88)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.lambda$execute$0(EngineExecutionOrchestrator.java:54)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.withInterceptedStreams(EngineExecutionOrchestrator.java:67)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:52)
	at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:114)
	at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:86)
	at org.junit.platform.launcher.core.DefaultLauncherSession$DelegatingLauncher.execute(DefaultLauncherSession.java:86)
	at org.junit.platform.launcher.core.SessionPerRequestLauncher.execute(SessionPerRequestLauncher.java:53)
	at com.intellij.junit5.JUnit5IdeaTestRunner.startRunnerWithArgs(JUnit5IdeaTestRunner.java:71)
	at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
	at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:235)
	at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:54)
Caused by: java.lang.ArithmeticException: / by zero
	at com.c3stones.test.CompletableFutureTest.lambda$testAcceptEitherException$84(CompletableFutureTest.java:1035)
	at java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1590)
	at java.util.concurrent.CompletableFuture$AsyncSupply.exec(CompletableFuture.java:1582)
	at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:289)
	at java.util.concurrent.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1056)
	at java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1692)
	at java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:157)

acceptEitherAsync

/**
 * 任务1或任务2执行成功，再执行回调函数

 * 回调函数入参为第一个完成的任务的返回结果，无返回值
 * 
 * 提交给线程池，不同线程执行
 * 
 */
@Test
public void testAcceptEitherAsync() throws ExecutionException, InterruptedException {
	ExecutorService executorService = Executors.newCachedThreadPool();

	CompletableFuture completableFuture1 = CompletableFuture.supplyAsync(() -> {
		log.info("任务 1 执行中...");
		try {
			TimeUnit.SECONDS.sleep(1);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		return 10;
	}, executorService);

	CompletableFuture completableFuture2 = CompletableFuture.supplyAsync(() -> {
		log.info("任务 2 执行中...");
		try {
			TimeUnit.SECONDS.sleep(2);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		return 20;
	}, executorService);

	CompletableFuture completableFuture3 = completableFuture1.acceptEitherAsync(completableFuture2, (result) -> {
		log.info("回调函数获取到结果：" + result);
		log.info("回调函数执行中...");
	}, executorService);

	log.info("任务 1 返回结果：" + completableFuture1.get());
	log.info("任务 2 返回结果：" + completableFuture2.get());
	log.info("回调函数返回结果：" + completableFuture3.get());
}

控制台输出：

22:21:27.580 [pool-1-thread-1] INFO com.c3stones.test.CompletableFutureTest - 任务 1 执行中...
22:21:27.636 [pool-1-thread-2] INFO com.c3stones.test.CompletableFutureTest - 任务 2 执行中...
22:21:28.601 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 1 返回结果：10
22:21:28.602 [pool-1-thread-3] INFO com.c3stones.test.CompletableFutureTest - 回调函数获取到结果：10
22:21:28.602 [pool-1-thread-3] INFO com.c3stones.test.CompletableFutureTest - 回调函数执行中...
22:21:29.637 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 2 返回结果：20
22:21:29.637 [main] INFO com.c3stones.test.CompletableFutureTest - 回调函数返回结果：null

/**
 * 任务1执行成功，任务2执行失败，再执行回调函数

 * 回调函数入参为第一个完成的任务的返回结果，无返回值
 * 
 * 提交给线程池，不同线程执行
 * 
 */
@Test
public void testAcceptEitherAsyncException() throws ExecutionException, InterruptedException {
	ExecutorService executorService = Executors.newCachedThreadPool();

	CompletableFuture completableFuture1 = CompletableFuture.supplyAsync(() -> {
		log.info("任务 1 执行中...");
		try {
			TimeUnit.SECONDS.sleep(1);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		return 10;
	}, executorService);

	CompletableFuture completableFuture2 = CompletableFuture.supplyAsync(() -> {
		log.info("任务 2 执行中...");
		try {
			TimeUnit.SECONDS.sleep(2);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		int a = 1 / 0;
		return 20;
	}, executorService);

	CompletableFuture completableFuture3 = completableFuture1.acceptEitherAsync(completableFuture2, (result) -> {
		log.info("回调函数获取到结果：" + result);
		log.info("回调函数执行中...");
	}, executorService);

	log.info("任务 1 返回结果：" + completableFuture1.get());
	log.info("任务 2 返回结果：" + completableFuture2.get());
	log.info("回调函数返回结果：" + completableFuture3.get());
}

控制台输出：

22:22:25.767 [pool-1-thread-2] INFO com.c3stones.test.CompletableFutureTest - 任务 2 执行中...
22:22:25.764 [pool-1-thread-1] INFO com.c3stones.test.CompletableFutureTest - 任务 1 执行中...
22:22:26.772 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 1 返回结果：10
22:22:26.772 [pool-1-thread-3] INFO com.c3stones.test.CompletableFutureTest - 回调函数获取到结果：10
22:22:26.772 [pool-1-thread-3] INFO com.c3stones.test.CompletableFutureTest - 回调函数执行中...

java.util.concurrent.ExecutionException: java.lang.ArithmeticException: / by zero

	at java.util.concurrent.CompletableFuture.reportGet(CompletableFuture.java:357)
	at java.util.concurrent.CompletableFuture.get(CompletableFuture.java:1895)
	at com.c3stones.test.CompletableFutureTest.testAcceptEitherAsyncException(CompletableFutureTest.java:1128)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.platform.commons.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:725)
	at org.junit.jupiter.engine.execution.MethodInvocation.proceed(MethodInvocation.java:60)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain$ValidatingInvocation.proceed(InvocationInterceptorChain.java:131)
	at org.junit.jupiter.engine.extension.TimeoutExtension.intercept(TimeoutExtension.java:149)
	at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestableMethod(TimeoutExtension.java:140)
	at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestMethod(TimeoutExtension.java:84)
	at org.junit.jupiter.engine.execution.ExecutableInvoker$ReflectiveInterceptorCall.lambda$ofVoidMethod$0(ExecutableInvoker.java:115)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.lambda$invoke$0(ExecutableInvoker.java:105)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain$InterceptedInvocation.proceed(InvocationInterceptorChain.java:106)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.proceed(InvocationInterceptorChain.java:64)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.chainAndInvoke(InvocationInterceptorChain.java:45)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.invoke(InvocationInterceptorChain.java:37)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:104)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:98)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$invokeTestMethod$7(TestMethodTestDescriptor.java:214)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.invokeTestMethod(TestMethodTestDescriptor.java:210)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:135)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:66)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:151)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at java.util.ArrayList.forEach(ArrayList.java:1249)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at java.util.ArrayList.forEach(ArrayList.java:1249)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:35)
	at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:57)
	at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:54)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:107)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:88)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.lambda$execute$0(EngineExecutionOrchestrator.java:54)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.withInterceptedStreams(EngineExecutionOrchestrator.java:67)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:52)
	at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:114)
	at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:86)
	at org.junit.platform.launcher.core.DefaultLauncherSession$DelegatingLauncher.execute(DefaultLauncherSession.java:86)
	at org.junit.platform.launcher.core.SessionPerRequestLauncher.execute(SessionPerRequestLauncher.java:53)
	at com.intellij.junit5.JUnit5IdeaTestRunner.startRunnerWithArgs(JUnit5IdeaTestRunner.java:71)
	at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
	at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:235)
	at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:54)
Caused by: java.lang.ArithmeticException: / by zero
	at com.c3stones.test.CompletableFutureTest.lambda$testAcceptEitherAsyncException$90(CompletableFutureTest.java:1118)
	at java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1590)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at java.lang.Thread.run(Thread.java:745)

3.3.6 runAfterEither/runAfterEitherAsync

runAfterEither和runAfterEitherAsync都是将两个异步任务组合后处理。回调函数无入参，也无返回值。如果两个任务有一个执行异常，则抛出异常。区别在于：runAfterEither执行回调函数时会公用第一个完成的任务的线程，而runAfterEitherAsync会使用不同的线程，并且runAfterEitherAsync支持指定线程池。

runAfterEither

/**
 * 任务1或任务2执行成功，再执行回调函数

 * 回调函数无入参，无返回值
 * 
 * 回调函数和第一个完成的任务使用相同线程执行
 * 
 */
@Test
public void testRunAfterEither() throws ExecutionException, InterruptedException {
	CompletableFuture completableFuture1 = CompletableFuture.supplyAsync(() -> {
		log.info("任务 1 执行中...");
		try {
			TimeUnit.SECONDS.sleep(1);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		return 10;
	});

	CompletableFuture completableFuture2 = CompletableFuture.supplyAsync(() -> {
		log.info("任务 2 执行中...");
		try {
			TimeUnit.SECONDS.sleep(2);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		return 20;
	});

	CompletableFuture completableFuture3 = completableFuture1.runAfterEither(completableFuture2, () -> {
		log.info("回调函数执行中...");
	});

	log.info("任务 1 返回结果：" + completableFuture1.get());
	log.info("任务 2 返回结果：" + completableFuture2.get());
	log.info("回调函数返回结果：" + completableFuture3.get());
}

控制台输出：

22:25:15.172 [ForkJoinPool.commonPool-worker-1] INFO com.c3stones.test.CompletableFutureTest - 任务 1 执行中...
22:25:15.252 [ForkJoinPool.commonPool-worker-2] INFO com.c3stones.test.CompletableFutureTest - 任务 2 执行中...
22:25:16.183 [ForkJoinPool.commonPool-worker-1] INFO com.c3stones.test.CompletableFutureTest - 回调函数执行中...
22:25:16.183 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 1 返回结果：10
22:25:17.253 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 2 返回结果：20
22:25:17.253 [main] INFO com.c3stones.test.CompletableFutureTest - 回调函数返回结果：null

/**
 * 任务1执行成功，任务2执行失败，再执行回调函数

 * 回调函数无入参，无返回值
 * 
 * 回调函数和第一个完成的任务使用相同线程执行
 * 
 */
@Test
public void testRunAfterEitherException() throws ExecutionException, InterruptedException {
	CompletableFuture completableFuture1 = CompletableFuture.supplyAsync(() -> {
		log.info("任务 1 执行中...");
		try {
			TimeUnit.SECONDS.sleep(1);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		return 10;
	});

	CompletableFuture completableFuture2 = CompletableFuture.supplyAsync(() -> {
		log.info("任务 2 执行中...");
		try {
			TimeUnit.SECONDS.sleep(2);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		int a = 1 / 0;
		return 20;
	});

	CompletableFuture completableFuture3 = completableFuture1.runAfterEither(completableFuture2, () -> {
		log.info("回调函数执行中...");
	});

	log.info("任务 1 返回结果：" + completableFuture1.get());
	log.info("任务 2 返回结果：" + completableFuture2.get());
	log.info("回调函数返回结果：" + completableFuture3.get());
}

控制台输出：

22:25:46.913 [ForkJoinPool.commonPool-worker-2] INFO com.c3stones.test.CompletableFutureTest - 任务 1 执行中...
22:25:46.913 [ForkJoinPool.commonPool-worker-1] INFO com.c3stones.test.CompletableFutureTest - 任务 2 执行中...
22:25:47.920 [ForkJoinPool.commonPool-worker-2] INFO com.c3stones.test.CompletableFutureTest - 回调函数执行中...
22:25:47.920 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 1 返回结果：10

java.util.concurrent.ExecutionException: java.lang.ArithmeticException: / by zero

	at java.util.concurrent.CompletableFuture.reportGet(CompletableFuture.java:357)
	at java.util.concurrent.CompletableFuture.get(CompletableFuture.java:1895)
	at com.c3stones.test.CompletableFutureTest.testRunAfterEitherException(CompletableFutureTest.java:1205)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.platform.commons.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:725)
	at org.junit.jupiter.engine.execution.MethodInvocation.proceed(MethodInvocation.java:60)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain$ValidatingInvocation.proceed(InvocationInterceptorChain.java:131)
	at org.junit.jupiter.engine.extension.TimeoutExtension.intercept(TimeoutExtension.java:149)
	at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestableMethod(TimeoutExtension.java:140)
	at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestMethod(TimeoutExtension.java:84)
	at org.junit.jupiter.engine.execution.ExecutableInvoker$ReflectiveInterceptorCall.lambda$ofVoidMethod$0(ExecutableInvoker.java:115)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.lambda$invoke$0(ExecutableInvoker.java:105)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain$InterceptedInvocation.proceed(InvocationInterceptorChain.java:106)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.proceed(InvocationInterceptorChain.java:64)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.chainAndInvoke(InvocationInterceptorChain.java:45)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.invoke(InvocationInterceptorChain.java:37)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:104)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:98)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$invokeTestMethod$7(TestMethodTestDescriptor.java:214)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.invokeTestMethod(TestMethodTestDescriptor.java:210)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:135)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:66)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:151)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at java.util.ArrayList.forEach(ArrayList.java:1249)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at java.util.ArrayList.forEach(ArrayList.java:1249)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:35)
	at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:57)
	at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:54)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:107)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:88)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.lambda$execute$0(EngineExecutionOrchestrator.java:54)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.withInterceptedStreams(EngineExecutionOrchestrator.java:67)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:52)
	at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:114)
	at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:86)
	at org.junit.platform.launcher.core.DefaultLauncherSession$DelegatingLauncher.execute(DefaultLauncherSession.java:86)
	at org.junit.platform.launcher.core.SessionPerRequestLauncher.execute(SessionPerRequestLauncher.java:53)
	at com.intellij.junit5.JUnit5IdeaTestRunner.startRunnerWithArgs(JUnit5IdeaTestRunner.java:71)
	at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
	at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:235)
	at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:54)
Caused by: java.lang.ArithmeticException: / by zero
	at com.c3stones.test.CompletableFutureTest.lambda$testRunAfterEitherException$96(CompletableFutureTest.java:1196)
	at java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1590)
	at java.util.concurrent.CompletableFuture$AsyncSupply.exec(CompletableFuture.java:1582)
	at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:289)
	at java.util.concurrent.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1056)
	at java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1692)
	at java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:157)

runAfterEitherAsync

/**
 * 任务1或任务2执行成功，再执行回调函数

 * 回调函数无入参，无返回值
 * 
 * 提交给线程池，不同线程执行
 * 
 */
@Test
public void testRunAfterEitherAsync() throws ExecutionException, InterruptedException {
	ExecutorService executorService = Executors.newCachedThreadPool();

	CompletableFuture completableFuture1 = CompletableFuture.supplyAsync(() -> {
		log.info("任务 1 执行中...");
		try {
			TimeUnit.SECONDS.sleep(1);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		return 10;
	}, executorService);

	CompletableFuture completableFuture2 = CompletableFuture.supplyAsync(() -> {
		log.info("任务 2 执行中...");
		try {
			TimeUnit.SECONDS.sleep(2);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		return 20;
	}, executorService);

	CompletableFuture completableFuture3 = completableFuture1.runAfterEitherAsync(completableFuture2, () -> {
		log.info("回调函数执行中...");
	}, executorService);

	log.info("任务 1 返回结果：" + completableFuture1.get());
	log.info("任务 2 返回结果：" + completableFuture2.get());
	log.info("回调函数返回结果：" + completableFuture3.get());
}

控制台输出：

22:26:24.311 [pool-1-thread-2] INFO com.c3stones.test.CompletableFutureTest - 任务 2 执行中...
22:26:24.311 [pool-1-thread-1] INFO com.c3stones.test.CompletableFutureTest - 任务 1 执行中...
22:26:25.318 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 1 返回结果：10
22:26:25.318 [pool-1-thread-3] INFO com.c3stones.test.CompletableFutureTest - 回调函数执行中...
22:26:26.318 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 2 返回结果：20
22:26:26.318 [main] INFO com.c3stones.test.CompletableFutureTest - 回调函数返回结果：null

/**
 * 任务1执行成功，任务2执行失败，再执行回调函数

 * 回调函数无入参，无返回值
 * 
 * 提交给线程池，不同线程执行
 * 
 */
@Test
public void testRunAfterEitherAsyncException() throws ExecutionException, InterruptedException {
	ExecutorService executorService = Executors.newCachedThreadPool();

	CompletableFuture completableFuture1 = CompletableFuture.supplyAsync(() -> {
		log.info("任务 1 执行中...");
		try {
			TimeUnit.SECONDS.sleep(1);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		return 10;
	}, executorService);

	CompletableFuture completableFuture2 = CompletableFuture.supplyAsync(() -> {
		log.info("任务 2 执行中...");
		try {
			TimeUnit.SECONDS.sleep(2);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		int a = 1 / 0;
		return 20;
	}, executorService);

	CompletableFuture completableFuture3 = completableFuture1.runAfterEitherAsync(completableFuture2, () -> {
		log.info("回调函数执行中...");
	}, executorService);

	log.info("任务 1 返回结果：" + completableFuture1.get());
	log.info("任务 2 返回结果：" + completableFuture2.get());
	log.info("回调函数返回结果：" + completableFuture3.get());
}

控制台输出：

22:27:06.844 [pool-1-thread-2] INFO com.c3stones.test.CompletableFutureTest - 任务 2 执行中...
22:27:06.844 [pool-1-thread-1] INFO com.c3stones.test.CompletableFutureTest - 任务 1 执行中...
22:27:07.850 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 1 返回结果：10
22:27:07.850 [pool-1-thread-3] INFO com.c3stones.test.CompletableFutureTest - 回调函数执行中...

java.util.concurrent.ExecutionException: java.lang.ArithmeticException: / by zero

	at java.util.concurrent.CompletableFuture.reportGet(CompletableFuture.java:357)
	at java.util.concurrent.CompletableFuture.get(CompletableFuture.java:1895)
	at com.c3stones.test.CompletableFutureTest.testRunAfterEitherAsyncException(CompletableFutureTest.java:1286)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.platform.commons.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:725)
	at org.junit.jupiter.engine.execution.MethodInvocation.proceed(MethodInvocation.java:60)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain$ValidatingInvocation.proceed(InvocationInterceptorChain.java:131)
	at org.junit.jupiter.engine.extension.TimeoutExtension.intercept(TimeoutExtension.java:149)
	at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestableMethod(TimeoutExtension.java:140)
	at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestMethod(TimeoutExtension.java:84)
	at org.junit.jupiter.engine.execution.ExecutableInvoker$ReflectiveInterceptorCall.lambda$ofVoidMethod$0(ExecutableInvoker.java:115)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.lambda$invoke$0(ExecutableInvoker.java:105)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain$InterceptedInvocation.proceed(InvocationInterceptorChain.java:106)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.proceed(InvocationInterceptorChain.java:64)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.chainAndInvoke(InvocationInterceptorChain.java:45)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.invoke(InvocationInterceptorChain.java:37)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:104)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:98)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$invokeTestMethod$7(TestMethodTestDescriptor.java:214)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.invokeTestMethod(TestMethodTestDescriptor.java:210)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:135)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:66)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:151)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at java.util.ArrayList.forEach(ArrayList.java:1249)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at java.util.ArrayList.forEach(ArrayList.java:1249)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:35)
	at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:57)
	at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:54)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:107)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:88)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.lambda$execute$0(EngineExecutionOrchestrator.java:54)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.withInterceptedStreams(EngineExecutionOrchestrator.java:67)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:52)
	at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:114)
	at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:86)
	at org.junit.platform.launcher.core.DefaultLauncherSession$DelegatingLauncher.execute(DefaultLauncherSession.java:86)
	at org.junit.platform.launcher.core.SessionPerRequestLauncher.execute(SessionPerRequestLauncher.java:53)
	at com.intellij.junit5.JUnit5IdeaTestRunner.startRunnerWithArgs(JUnit5IdeaTestRunner.java:71)
	at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
	at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:235)
	at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:54)
Caused by: java.lang.ArithmeticException: / by zero
	at com.c3stones.test.CompletableFutureTest.lambda$testRunAfterEitherAsyncException$102(CompletableFutureTest.java:1277)
	at java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1590)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at java.lang.Thread.run(Thread.java:745)

3.3.7 allOf

allOf将多个任务组合后处理，当所有任务都执行成功后，返回null，只要有一个任务执行异常，则抛出异常。

任务1、任务2、任务3都执行成功

/**
 * 任务1、任务2、任务3都执行成功，返回null
 */
@Test
public void testAllOf() throws ExecutionException, InterruptedException {
	CompletableFuture completableFuture1 = CompletableFuture.supplyAsync(() -> {
		log.info("任务 1 执行中...");
		try {
			TimeUnit.SECONDS.sleep(1);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		return 10;
	});

	CompletableFuture completableFuture2 = CompletableFuture.supplyAsync(() -> {
		log.info("任务 2 执行中...");
		try {
			TimeUnit.SECONDS.sleep(2);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		return 20;
	});

	CompletableFuture completableFuture3 = CompletableFuture.supplyAsync(() -> {
		log.info("任务 3 执行中...");
		try {
			TimeUnit.SECONDS.sleep(3);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		return 30;
	});

	CompletableFuture completableFuture = CompletableFuture.allOf(completableFuture1, completableFuture2, completableFuture3);

	log.info("任务 1 返回结果：" + completableFuture1.get());
	log.info("任务 2 返回结果：" + completableFuture2.get());
	log.info("任务 3 返回结果：" + completableFuture3.get());
	log.info("全部任务返回结果：" + completableFuture.get());
}

控制台输出：

22:32:05.089 [ForkJoinPool.commonPool-worker-1] INFO com.c3stones.test.CompletableFutureTest - 任务 2 执行中...
22:32:05.089 [ForkJoinPool.commonPool-worker-2] INFO com.c3stones.test.CompletableFutureTest - 任务 1 执行中...
22:32:05.091 [ForkJoinPool.commonPool-worker-4] INFO com.c3stones.test.CompletableFutureTest - 任务 3 执行中...
22:32:06.095 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 1 返回结果：10
22:32:07.096 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 2 返回结果：20
22:32:08.095 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 3 返回结果：30
22:32:08.095 [main] INFO com.c3stones.test.CompletableFutureTest - 全部任务返回结果：null

任务1、任务3执行成功，任务2执行异常

/**
 * 任务1、任务3执行成功，任务2执行异常
 */
@Test
public void testAllOfException() throws ExecutionException, InterruptedException {
	CompletableFuture completableFuture1 = CompletableFuture.supplyAsync(() -> {
		log.info("任务 1 执行中...");
		try {
			TimeUnit.SECONDS.sleep(1);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		return 10;
	});

	CompletableFuture completableFuture2 = CompletableFuture.supplyAsync(() -> {
		log.info("任务 2 执行中...");
		try {
			TimeUnit.SECONDS.sleep(2);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		int a = 1 / 0;
		return 20;
	});

	CompletableFuture completableFuture3 = CompletableFuture.supplyAsync(() -> {
		log.info("任务 3 执行中...");
		try {
			TimeUnit.SECONDS.sleep(3);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		return 30;
	});

	CompletableFuture completableFuture = CompletableFuture.allOf(completableFuture1, completableFuture2, completableFuture3);

	log.info("任务 1 返回结果：" + completableFuture1.get());
	log.info("任务 2 返回结果：" + completableFuture2.get());
	log.info("任务 3 返回结果：" + completableFuture3.get());
	log.info("全部任务返回结果：" + completableFuture.get());
}

控制台输出：

22:34:03.486 [ForkJoinPool.commonPool-worker-2] INFO com.c3stones.test.CompletableFutureTest - 任务 2 执行中...
22:34:03.486 [ForkJoinPool.commonPool-worker-1] INFO com.c3stones.test.CompletableFutureTest - 任务 1 执行中...
22:34:03.486 [ForkJoinPool.commonPool-worker-3] INFO com.c3stones.test.CompletableFutureTest - 任务 3 执行中...
22:34:04.499 [main] INFO com.c3stones.test.CompletableFutureTest - 任务 1 返回结果：10

java.util.concurrent.ExecutionException: java.lang.ArithmeticException: / by zero

	at java.util.concurrent.CompletableFuture.reportGet(CompletableFuture.java:357)
	at java.util.concurrent.CompletableFuture.get(CompletableFuture.java:1895)
	at com.c3stones.test.CompletableFutureTest.testAllOfException(CompletableFutureTest.java:1372)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.platform.commons.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:725)
	at org.junit.jupiter.engine.execution.MethodInvocation.proceed(MethodInvocation.java:60)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain$ValidatingInvocation.proceed(InvocationInterceptorChain.java:131)
	at org.junit.jupiter.engine.extension.TimeoutExtension.intercept(TimeoutExtension.java:149)
	at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestableMethod(TimeoutExtension.java:140)
	at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestMethod(TimeoutExtension.java:84)
	at org.junit.jupiter.engine.execution.ExecutableInvoker$ReflectiveInterceptorCall.lambda$ofVoidMethod$0(ExecutableInvoker.java:115)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.lambda$invoke$0(ExecutableInvoker.java:105)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain$InterceptedInvocation.proceed(InvocationInterceptorChain.java:106)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.proceed(InvocationInterceptorChain.java:64)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.chainAndInvoke(InvocationInterceptorChain.java:45)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.invoke(InvocationInterceptorChain.java:37)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:104)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:98)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$invokeTestMethod$7(TestMethodTestDescriptor.java:214)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.invokeTestMethod(TestMethodTestDescriptor.java:210)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:135)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:66)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:151)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at java.util.ArrayList.forEach(ArrayList.java:1249)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at java.util.ArrayList.forEach(ArrayList.java:1249)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:35)
	at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:57)
	at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:54)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:107)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:88)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.lambda$execute$0(EngineExecutionOrchestrator.java:54)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.withInterceptedStreams(EngineExecutionOrchestrator.java:67)
	at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:52)
	at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:114)
	at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:86)
	at org.junit.platform.launcher.core.DefaultLauncherSession$DelegatingLauncher.execute(DefaultLauncherSession.java:86)
	at org.junit.platform.launcher.core.SessionPerRequestLauncher.execute(SessionPerRequestLauncher.java:53)
	at com.intellij.junit5.JUnit5IdeaTestRunner.startRunnerWithArgs(JUnit5IdeaTestRunner.java:71)
	at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
	at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:235)
	at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:54)
Caused by: java.lang.ArithmeticException: / by zero
	at com.c3stones.test.CompletableFutureTest.lambda$testAllOfException$108(CompletableFutureTest.java:1355)
	at java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1590)
	at java.util.concurrent.CompletableFuture$AsyncSupply.exec(CompletableFuture.java:1582)
	at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:289)
	at java.util.concurrent.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1056)
	at java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1692)
	at java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:157)

3.3.8 anyOf

anyOf将多个任务组合后处理，只要有一个任务执行成功，返回该任务结果，只要有一个任务执行异常，则抛出异常。

任务1、任务2、任务3只要有一个任务执行成功，返回该任务结果

/**
 * 任务1、任务2、任务3只要有一个任务执行成功，返回该任务结果
 */
@Test
public void testAnyOf() throws ExecutionException, InterruptedException {
	CompletableFuture completableFuture1 = CompletableFuture.supplyAsync(() -> {
		log.info("任务 1 执行中...");
		try {
			TimeUnit.SECONDS.sleep(1);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		return 10;
	});

	CompletableFuture completableFuture2 = CompletableFuture.supplyAsync(() -> {
		log.info("任务 2 执行中...");
		try {
			TimeUnit.SECONDS.sleep(2);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		return 20;
	});

	CompletableFuture completableFuture3 = CompletableFuture.supplyAsync(() -> {
		log.info("任务 3 执行中...");
		try {
			TimeUnit.SECONDS.sleep(3);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		return 30;
	});

	CompletableFuture

方法名称及参数	描述
T get() throws InterruptedException, ExecutionException	获取结果
T get(long timeout, TimeUnit unit) throws InterruptedException, ExecutionException, TimeoutException	获取结果，超时自动退出
T getNow(T valueIfAbsent)	获取结果，未完成则返回传入的预期值
T join()	获取结果，和get()一样。区别在于：get()会抛出异常，join()不会抛出异常，出现异常时抛出未经检查( CompletionException)异常
boolean complete(T value)	设置任务完成，完成后所有阻塞方法获取到结果。如果未完成，则返回传入的预期值，一般非执行任务的线程调用
boolean completeExceptionally(Throwable ex)	设置任务完成，完成后所有阻塞方法获取到结果。如果未完成，则抛出传入的异常，一般非执行任务的线程调

【面试专栏】Java8 - CompletableFuture，增强版Future

1. 简介

2. 相关博客

3. CompletableFuture应用

3.1 supplyAsync/runAsync

3.2 流式连接函数

3.2.1 thenApply/thenApplyAsync

3.2.2 thenAccept/thenAcceptAsync

3.2.3 thenRun/thenRunAsync

3.2.4 whenComplete/whenCompleteAsync

3.2.5 handle/handleAsync

3.3 多任务组合

3.3.1 thenCombine/thenCombineAsync

3.3.2 thenAcceptBoth/thenAcceptBothAsync

3.3.3 runAfterBoth/runAfterBothAsync

3.3.4 applyToEither/applyToEitherAsync

3.3.5 acceptEither/acceptEitherAsync

3.3.6 runAfterEither/runAfterEitherAsync

3.3.7 allOf

3.3.8 anyOf

3.4 获取结果

4. 项目地址

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