CompletableFuture用法

描述

提供异步处理

public class CompletableFutureTest {

    @Test
    public void testCreate() {
        CompletableFuture future = new CompletableFuture<>();
        // 手工完成future
        future.complete("hello,completableFuture");
        try {
            String s = future.get();
            System.out.println(s);
        } catch (InterruptedException | ExecutionException e) {
            e.printStackTrace();
        }
    }

    @Test
    public void testRunAsync() {
        CompletableFuture future = CompletableFuture.runAsync(() -> {
            try {
                Thread.sleep(3000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        });

        try {
            // 该方法阻塞，直到future completed
            Void aVoid = future.get();
            System.out.println(aVoid);

        } catch (InterruptedException | ExecutionException e) {
            e.printStackTrace();
        }

    }

    @Test
    public void testSupplyAsync() {
        CompletableFuture future = CompletableFuture.supplyAsync(() -> {
            try {
                Thread.sleep(3000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            return "I finish completing";
        });

        if (future.isDone()) {
            System.out.println("done " + future.getNow("I can`t find"));
        } else {
            try {
                System.out.println("not done " + future.get());
            } catch (InterruptedException e) {
                e.printStackTrace();
            } catch (ExecutionException e) {
                e.printStackTrace();
            }
        }
    }

    @Test
    public void testThenSupply() {
        CompletableFuture future = CompletableFuture.supplyAsync(() -> {
            try {
                Thread.sleep(3000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            return "I am a word";
        }).thenApply((word) -> {
            return word + ",I am a new word";
        });

        try {
            System.out.println(future.get());
        } catch (InterruptedException e) {
            e.printStackTrace();
        } catch (ExecutionException e) {
            e.printStackTrace();
        }
    }

    @Test
    public void testThenRun() {
        AtomicBoolean close = new AtomicBoolean(true);
        CompletableFuture future = CompletableFuture.runAsync(() -> {
            try {
                Thread.sleep(3000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println("I am a King");
        }).thenRun(() -> {
            System.out.println("I am a Queen");
            close.set(false);
        });

        while (close.get()) {

        }

    }
}

引用

https://colobu.com/2018/03/12/20-Examples-of-Using-Java%E2%80%99s-CompletableFuture/
https://colobu.com/2016/02/29/Java-CompletableFuture/
https://mahmoudanouti.wordpress.com/2018/01/26/20-examples-of-using-javas-completablefuture/
https://juejin.im/post/5adbf8226fb9a07aac240a67