異步執行一組任務等待所有任務執行完成的2種方式

 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
     * 主線程統一收集結果，適用於希望單一任務設置超時
     */
    @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
     * 子線程自己添加結果，適用於希望整體有一個等待超時
     */
    @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();
        };
    }