CountDownLatch、ExecutorService的使用

public class TestService {

    public static void main(String[] args) {
        CountDownLatch countDownLatch = new CountDownLatch(50);
        //开启一个线程池
        ExecutorService executor = Executors.newCachedThreadPool();
        //执行TestThread里面的run方法
        executor.execute(new TestThread(countDownLatch));
        executor.execute(new TestThread(countDownLatch));
        executor.execute(new TestThread(countDownLatch));
        //线程池不再接受新的任务
        executor.shutdown();
    }
}

• executor.execute(new TestThread(countDownLatch));这段传入的是一个实现Runnable接口的类，执行的方法则是run方法里面的内容，每一个execute则是开启一个线程

public class TestThread implements Runnable{
    private  CountDownLatch countDownLatch;
    public TestThread( CountDownLatch countDownLatch ){
        this.countDownLatch = countDownLatch;
    }

    public void run() {
        while (countDownLatch.getCount() >0){
            countDownLatch.countDown();
            System.out.println("输出："+Thread.currentThread()+">>>"+ countDownLatch.getCount());
        }
    }
}

• CountDownLatch countDownLatch = new CountDownLatch(50);这段是启用一个线程辅助类，传入的参数是一个int类型的计数，在TestThread中的run方法中，每执行一次，通过调用countDownLatch.countDown();方法计数减一，当计数内容为0时，则子线程全部执行完成，此时主线程才能继续往下执行。

输出结果

输出：Thread[pool-1-thread-1,5,main]>>>49
输出：Thread[pool-1-thread-1,5,main]>>>47
输出：Thread[pool-1-thread-1,5,main]>>>46
输出：Thread[pool-1-thread-1,5,main]>>>45
输出：Thread[pool-1-thread-1,5,main]>>>44
输出：Thread[pool-1-thread-1,5,main]>>>43
输出：Thread[pool-1-thread-1,5,main]>>>42
输出：Thread[pool-1-thread-1,5,main]>>>41
输出：Thread[pool-1-thread-1,5,main]>>>40
输出：Thread[pool-1-thread-2,5,main]>>>48
输出：Thread[pool-1-thread-1,5,main]>>>39
输出：Thread[pool-1-thread-2,5,main]>>>38
输出：Thread[pool-1-thread-3,5,main]>>>36
输出：Thread[pool-1-thread-1,5,main]>>>36
输出：Thread[pool-1-thread-3,5,main]>>>34
...

具体用法请google