spring-boot @Async 的使用、自定义Executor的配置方法

简单几步，实现异步新线程调用。

1、在主类中添加@EnableAsync注解：

 @SpringBootApplication
 @EnableScheduling
 @EnableAsync
 public class MySpringBootApplication {
     private static Logger logger = LoggerFactory.getLogger(MySpringBootApplication.class);

     public static void main(String[] args) {
         SpringApplication.run(MySpringBootApplication.class, args);
         logger.info("My Spring Boot Application Started");
     }


 }

2、创建一个AsyncTask类，在里面添加两个用@Async注解的task：

 /**
  * Asynchronous Tasks
  * @author Xu
  *
  */
 @Component
 public class AsyncTask {
     protected final Logger logger = LoggerFactory.getLogger(this.getClass());

     @Async
     public Future doTask1() throws InterruptedException{
         logger.info("Task1 started.");
         long start = System.currentTimeMillis();
         Thread.sleep(5000);
         long end = System.currentTimeMillis();

         logger.info("Task1 finished, time elapsed: {} ms.", end-start);

         return new AsyncResult<>("Task1 accomplished!");
     }

     @Async
     public Future doTask2() throws InterruptedException{
         logger.info("Task2 started.");
         long start = System.currentTimeMillis();
         Thread.sleep(3000);
         long end = System.currentTimeMillis();

         logger.info("Task2 finished, time elapsed: {} ms.", end-start);

         return new AsyncResult<>("Task2 accomplished!");
     }
 }

3、万事俱备，开始测试：

 public class TaskTests extends BasicUtClass{
     @Autowired
     private AsyncTask asyncTask;


     @Test
     public void AsyncTaskTest() throws InterruptedException, ExecutionException {
         Future task1 = asyncTask.doTask1();
         Future task2 = asyncTask.doTask2();

         while(true) {
             if(task1.isDone() && task2.isDone()) {
                 logger.info("Task1 result: {}", task1.get());
                 logger.info("Task2 result: {}", task2.get());
                 break;
             }
             Thread.sleep(1000);
         }

         logger.info("All tasks finished.");
     }
 }

测试结果：

 2016-12-13 11:12:24,850:INFO main (AsyncExecutionAspectSupport.java:245) - No TaskExecutor bean found for async processing
 2016-12-13 11:12:24,864:INFO SimpleAsyncTaskExecutor-1 (AsyncTask.java:22) - Task1 started.
 2016-12-13 11:12:24,865:INFO SimpleAsyncTaskExecutor-2 (AsyncTask.java:34) - Task2 started.
 2016-12-13 11:12:27,869:INFO SimpleAsyncTaskExecutor-2 (AsyncTask.java:39) - Task2 finished, time elapsed: 3001 ms.
 2016-12-13 11:12:29,866:INFO SimpleAsyncTaskExecutor-1 (AsyncTask.java:27) - Task1 finished, time elapsed: 5001 ms.
 2016-12-13 11:12:30,853:INFO main (TaskTests.java:23) - Task1 result: Task1 accomplished!
 2016-12-13 11:12:30,853:INFO main (TaskTests.java:24) - Task2 result: Task2 accomplished!
 2016-12-13 11:12:30,854:INFO main (TaskTests.java:30) - All tasks finished.

可以看到，没有自定义的Executor，所以使用缺省的TaskExecutor 。

前面是最简单的使用方法。如果想使用自定义的Executor，可以按照如下几步来：

1、新建一个Executor配置类，顺便把@EnableAsync注解搬到这里来：

 @Configuration
 @EnableAsync
 public class ExecutorConfig {

     /** Set the ThreadPoolExecutor's core pool size. */
     private int corePoolSize = 10;
     /** Set the ThreadPoolExecutor's maximum pool size. */
     private int maxPoolSize = 200;
     /** Set the capacity for the ThreadPoolExecutor's BlockingQueue. */
     private int queueCapacity = 10;

     @Bean
     public Executor mySimpleAsync() {
         ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
         executor.setCorePoolSize(corePoolSize);
         executor.setMaxPoolSize(maxPoolSize);
         executor.setQueueCapacity(queueCapacity);
         executor.setThreadNamePrefix("MySimpleExecutor-");
         executor.initialize();
         return executor;
     }

     @Bean
     public Executor myAsync() {
         ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
         executor.setCorePoolSize(corePoolSize);
         executor.setMaxPoolSize(maxPoolSize);
         executor.setQueueCapacity(queueCapacity);
         executor.setThreadNamePrefix("MyExecutor-");

         // rejection-policy：当pool已经达到max size的时候，如何处理新任务
         // CALLER_RUNS：不在新线程中执行任务，而是有调用者所在的线程来执行
         executor.setRejectedExecutionHandler(new ThreadPoolExecutor.CallerRunsPolicy());
         executor.initialize();
         return executor;
     }
 }

这里定义了两个不同的Executor，第二个重新设置了pool已经达到max size时候的处理方法；同时指定了线程名字的前缀。

2、自定义Executor的使用：

 /**
  * Asynchronous Tasks
  * @author Xu
  *
  */
 @Component
 public class AsyncTask {
     protected final Logger logger = LoggerFactory.getLogger(this.getClass());

     @Async("mySimpleAsync")
     public Future doTask1() throws InterruptedException{
         logger.info("Task1 started.");
         long start = System.currentTimeMillis();
         Thread.sleep(5000);
         long end = System.currentTimeMillis();

         logger.info("Task1 finished, time elapsed: {} ms.", end-start);

         return new AsyncResult<>("Task1 accomplished!");
     }

     @Async("myAsync")
     public Future doTask2() throws InterruptedException{
         logger.info("Task2 started.");
         long start = System.currentTimeMillis();
         Thread.sleep(3000);
         long end = System.currentTimeMillis();

         logger.info("Task2 finished, time elapsed: {} ms.", end-start);

         return new AsyncResult<>("Task2 accomplished!");
     }
 }

就是把上面自定义Executor的类名，放进@Async注解中。

3、测试（测试用例不变）结果：

 2016-12-13 10:57:11,998:INFO MySimpleExecutor-1 (AsyncTask.java:22) - Task1 started.
 2016-12-13 10:57:12,001:INFO MyExecutor-1 (AsyncTask.java:34) - Task2 started.
 2016-12-13 10:57:15,007:INFO MyExecutor-1 (AsyncTask.java:39) - Task2 finished, time elapsed: 3000 ms.
 2016-12-13 10:57:16,999:INFO MySimpleExecutor-1 (AsyncTask.java:27) - Task1 finished, time elapsed: 5001 ms.
 2016-12-13 10:57:17,994:INFO main (TaskTests.java:23) - Task1 result: Task1 accomplished!
 2016-12-13 10:57:17,994:INFO main (TaskTests.java:24) - Task2 result: Task2 accomplished!
 2016-12-13 10:57:17,994:INFO main (TaskTests.java:30) - All tasks finished.
 2016-12-13 10:57:18,064 Thread-3 WARN Unable to register Log4j shutdown hook because JVM is shutting down. Using SimpleLogger

可见，线程名字的前缀变了，两个task使用了不同的线程池了。

源代码：https://github.com/xujijun/my-spring-boot