CountDownLatch的使用

        CountDownLatch是java中一个协调多线程的工具类，假如多线程在执行后，需要等待所有都执行完再执行下一步，那么就可以使用CountDownLatch。

        比如将会有10个线程，那么可以CountDownLatch latch =new CountDownLatch(10)，在每个线程内减少值(latch.countDown())，在下面就可以使用latch.await()方法等待所有线程都执行完成，才继续执行下去。还可以将多线程内报的错误带出来，详情见代码中AtomicReference> exe =new AtomicReference<>(new ArrayList<>());

public void excuteThread(int num)throws Throwable {

MyThreadConfig threadConfig =new MyThreadConfig();

    ThreadPoolTaskExecutor executor = threadConfig.taskExecutor();

    int excuteTimes = num /10;

    CountDownLatch latch =new CountDownLatch(excuteTimes);

    AtomicInteger count =new AtomicInteger(0);

    AtomicReference<List<Exception>> exe = new AtomicReference<>(new ArrayList<>());

    for (int i =0; i < excuteTimes; i++) {

        int finalI = i;

        executor.execute(() -> {

            Thread.currentThread().setName("thread-" +finalI);

            System.out.println(Thread.currentThread().getId());

            System.out.println(Thread.currentThread().getName() +" sleep begin");

            try {

                Thread.sleep(500);

                if (finalI ==0) {

                    throw new RuntimeException("第0个的错");

                }

            if (finalI ==1) {

                throw new RuntimeException("第1个的错");

                }

                if (finalI ==2) {

                        throw new RuntimeException("第2个的错");

                }

                    if (finalI ==4) {

                        int a =1 /0;

                        }

                    count.incrementAndGet();

                }catch (Exception e) {

                    e.printStackTrace();

                        exe.get().add(e);

                }finally {

                    latch.countDown();

                }

                    System.out.println(Thread.currentThread().getName() +"sleep over");

        });

    }

    latch.await();

    if (count.get() != excuteTimes) {

        exe.get().forEach(e -> {

        e.printStackTrace();

        });

        throw new RuntimeException("多线程内部报错了!");

    }

    System.out.println("顺利执行完成!");

}