1、测试异步调用：

static void testCompletableFuture1() throws ExecutionException, InterruptedException {
        // 1、无返回值的异步任务。异步线程执行Runnable
        CompletableFuture.runAsync(() -> System.out.println("only you"));

        // 2、有返回值的异步任务。执行Supplier函数并返回结果
        CompletableFuture<String> future = CompletableFuture.supplyAsync(() -> "3个时辰内必须找人解毒，不过老夫也可以帮忙哦");
        System.out.println("supplyAsync, result: " + future.get()); // 阻塞获取结果
    }

打印：

2、链式调用：

static void testCompletableFuture2() throws ExecutionException, InterruptedException {
        System.out.println("main thread, id: " +  Thread.currentThread().getId());
        // 链式操作
        CompletableFuture<String> future = CompletableFuture.supplyAsync(() -> {
            System.out.println("supplyAsync thread: " + Thread.currentThread().getId());
            return "我行我素";
        });
        // 结果转换
        future = future.thenApply(s -> {
            System.out.println("thenApply thread: " + Thread.currentThread().getId());
            return s + " !!!";
        });
        // 结果消费
        CompletableFuture<Void> future2 = future.thenAccept(s -> {
            System.out.println("thenAccept thread: " + Thread.currentThread().getId());
            System.out.println(s);// 输出结果
        });
    }

打印：

3、依赖其他Future任务

// thenCompose()串联多个异步任务,前一个任务结果为后一个任务的输入
    static void testCompletableFuture3() throws ExecutionException, InterruptedException {
        CompletableFuture<String> future = CompletableFuture.supplyAsync(() -> "haiyangxuanfeng");
        future = future.thenCompose(s -> CompletableFuture.supplyAsync(s::toUpperCase));
        future.thenAccept(new Consumer<String>() {
            @Override
            public void accept(String s) {
                System.out.println(s);
            }
        }).get();
    }

打印：