Java8 CompletableFuture 异步执行 Java8 CompletableFuture 异步执行操作

public static void main(String[] args) throws ExecutionException, InterruptedException {
    CompletableFuture<Void> future = CompletableFuture.runAsync(() -> {
        for (int i = 0; i < 3; i++) {
            System.out.println(i);
            try {
                Thread.sleep(1000L);
            } catch (InterruptedException ignored) {
            }
        }
        System.out.println("Future Finished.");
    });
    System.out.println("Main Thread Finished.");
    future.get();
}

public static void main(String[] args) throws ExecutionException, InterruptedException {
    // runAsync 没有返回值
    CompletableFuture<Void> future1 = CompletableFuture.runAsync(() -> System.out.println("future1 executed."));
    // supplyAsync 有返回值
    CompletableFuture<Object> future2 = CompletableFuture.supplyAsync(() -> {
        System.out.println("future2 executed.");
        return "result";
    });

    System.out.println("future1.get(): " + future1.get());
    System.out.println("future2.get(): " + future2.get());
}

public static void main(String[] args) {
    ExecutorService executorService = Executors.newFixedThreadPool(2);
    // 1.执行时间 < 主线程，会打印
    CompletableFuture<Void> future1 = CompletableFuture.runAsync(() ->
		System.out.println("Thread1 是否为守护线程 : " + Thread.currentThread().isDaemon()));

    // 2.执行时间 > 主线程，是守护线程，会被杀死，不会打印
    CompletableFuture.runAsync(() -> {
        try {
            Thread.sleep(3000L);
            System.out.println("Thread2 是否为守护线程 : " + Thread.currentThread().isDaemon());
        } catch (InterruptedException e) {
            e.printStackTrace();
        }});

    // 3.执行时间 > 主线程，但是不是守护线程，不会被杀死，会打印
    CompletableFuture.runAsync(() -> {
        try {
            Thread.sleep(1000L);
            System.out.println("Thread3 等待1秒");
            System.out.println("Thread3 是否为守护线程 : " + Thread.currentThread().isDaemon());
        } catch (InterruptedException e) {
            e.printStackTrace();
        }}, executorService);

    // 4.ExecutorService.submit()，默认不是守护线程，不会被杀死，会打印。
    executorService.submit(() -> {
        try {
            Thread.sleep(2000L);
            System.out.println("Thread4 等待2秒");
            System.out.println("Thread4 是否为守护线程 : " + Thread.currentThread().isDaemon());
        } catch (InterruptedException e) {
            e.printStackTrace();
        }});

    // 主线程执行完毕
    System.out.println("Main Thread Finished.");
    executorService.shutdown();
}

public static void main(String[] args) {
    // thenAccept对结果进行使用
    System.out.println("------------------------------");
    CompletableFuture.supplyAsync(() -> "Thread1 Finished.").thenAccept(System.out::println);

    // thenApply对结果进行转换
    System.out.println("------------------------------");
    CompletableFuture.supplyAsync(() -> "Thread2 Finished.")
        .thenApply(s -> s + " + thenApply()")
        .thenAccept(System.out::println);

    // exceptionally对异常进行处理
    System.out.println("------------------------------");
    CompletableFuture.supplyAsync(() -> {throw new RuntimeException("Thread3 Failed.");})
        .exceptionally(Throwable::toString).thenAccept(System.out::println);

    // 主线程执行完毕
    System.out.println("------------------------------");
    System.out.println("Main Thread Finished.");
}

public static void main(String[] args) throws ExecutionException, InterruptedException {
    // thenAccept对结果进行使用
    System.out.println("------------------------------");
    CompletableFuture<String> future = CompletableFuture.supplyAsync(() -> "Thread1 Finished.").whenComplete(new BiConsumer<String, Throwable>() {
        @Override
        public void accept(String s, Throwable throwable) {
            System.out.println("result: " + s);
            System.out.println("throwable: " + throwable);
        }
    });

    // exceptionally对异常进行处理
    System.out.println("------------------------------");
    CompletableFuture.supplyAsync(() -> {
        throw new RuntimeException("Thread3 Failed.");
    }).whenComplete(new BiConsumer<Object, Throwable>() {
        @Override
        public void accept(Object s, Throwable throwable) {
            System.out.println("result: " + s);
            System.out.println("throwable: " + throwable);
        }
    });

    System.out.println("------------------------------");
    System.out.println("future.get(): " + future.get());

    // 主线程执行完毕
    System.out.println("------------------------------");
    System.out.println("Main Thread Finished.");
}