多线程执行带有返回结果

CompletableFuture 通用异步编程

1. 多线程异步执行,带有返回值方法,避免使用get获取结果集会阻塞线程.

2. 具体执行业务逻辑方法

       () -> { System.out.println(Thread.currentThread().getName() + "------come in");
        int result = ThreadLocalRandom.current().nextInt(10);
        try {
            TimeUnit.SECONDS.sleep(1);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("---计算完成等待一秒钟输出结果");
        return result;

3. 正常执行结束

        if (e == null) {
            System.out.println("输出完成" + v);
        }

4. 异常执行结束

      e.printStackTrace();
        System.out.println("执行异常");
        return null;

5. CompletableFuture好处

     public static void main(String[] args) {
   ExecutorService executorService = Executors.newFixedThreadPool(3);
    try {
        CompletableFuture.supplyAsync(() -> {
            System.out.println(Thread.currentThread().getName() + "------come in");
            int result = ThreadLocalRandom.current().nextInt(10);
            try {   TimeUnit.SECONDS.sleep(1);  } catch (InterruptedException e) { e.printStackTrace();  }
            System.out.println("---计算完成等待一秒钟输出结果");
            return result;
        },executorService).whenComplete((v, e) -> {//当执行结束
            if (e == null) {System.out.println("输出完成" + v);} }).exceptionally(e -> {e.printStackTrace();System.out.println("执行异常");
            return null;
        });
        System.out.println("主线程执行其他任务");
        //主线程不要立刻结束,否则CompletableFuture默认使用的线程池会立刻关闭,暂停三秒钟结束
        try {
            TimeUnit.SECONDS.sleep(3);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        executorService.shutdown();
    }
}

简化执行任务闭并返回数据

    ExecutorService executorService = Executors.newFixedThreadPool(3);
    //调用异步有返回值方法
    CompletableFuture<String> completableFuture = CompletableFuture.supplyAsync(() -> {
        System.out.println(Thread.currentThread().getName());
        return "hello word";
    },executorService);
    System.out.println(completableFuture.get());
    executorService.shutdown();

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