异步执行一组任务等待所有任务执行完成的2种方式

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我是靠谱客的博主强健百褶裙，最近开发中收集的这篇文章主要介绍异步执行一组任务等待所有任务执行完成的2种方式，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

 private static ThreadPoolExecutor threadPool = new ThreadPoolExecutor(5, 10, 60, TimeUnit.SECONDS,
        new ArrayBlockingQueue<>(1000), new ThreadFactoryBuilder().setNameFormat("metrix-pool-%d").build(), new ThreadPoolExecutor.AbortPolicy());

    /** 方式一
     * 主线程统一收集结果，适用于希望单一任务设置超时
     */
    @Test
    public void test1() {
        long begin = System.currentTimeMillis();

        List<Future<Integer>> result = IntStream.rangeClosed(1, 4).mapToObj(i -> threadPool.submit(getAsyncTask(i)))
            .collect(Collectors.toList());

        List<Integer> list = result.stream().map(future -> {

            try {
                return future.get();
            } catch (Exception e) {
                e.printStackTrace();
                return -1;

            }

        }).collect(Collectors.toList());

        log.info("result {} took {} ms", JSON.toJSONString(list), System.currentTimeMillis() - begin);

    }

    private Callable<Integer> getAsyncTask(int i) {

        return () -> {

            TimeUnit.SECONDS.sleep(i);
            return i;
        };

    }

    /**  方式二
     * 子线程自己添加结果，适用于希望整体有一个等待超时
     */
    @Test
    public void test02() {
        long begin = System.currentTimeMillis();
        CountDownLatch countDownLatch = new CountDownLatch(4);
        List<Integer> result = new ArrayList<>();

        IntStream.rangeClosed(1, 4).forEach(i ->
            threadPool.execute(executeAsyncTask(i, countDownLatch, result))
        );

        try {

            countDownLatch.await(6,TimeUnit.SECONDS);
        } catch (InterruptedException e) {

        }

        log.info("result {} took {} ms", JSON.toJSONString(result), System.currentTimeMillis() - begin);

    }

    private Runnable executeAsyncTask(int i, CountDownLatch countDownLatch, List<Integer> result) {
        return () -> {

            try {
                TimeUnit.SECONDS.sleep(i);

            } catch (Exception e) {
                e.printStackTrace();
            }

            synchronized (result) {
                result.add(i);
            }

            countDownLatch.countDown();
        };
    }