/** *  * @描述: 倒计时器 . * 犹如倒计时计数器，调用CountDownLatch对象的countDown方法就将计数器减1，当计算器为0的时候 * 则所有等待者或单个等待者开始执行 * @作者: Wnj . * @创建时间: 2017年5月15日 . * @版本: 1.0 . */public class CountdownLatchTest {        public static void main(String[] args) {        ExecutorService service = Executors.newCachedThreadPool();                //吹口哨        final CountDownLatch cdOrder = new CountDownLatch(1);                //等待结果        final CountDownLatch cdAnswer = new CountDownLatch(3);        for (int i = 0; i < 3; i++) {            Runnable runnable = new Runnable() {                public void run() {                    try {                        System.out.println("线程" + Thread.currentThread().getName() + "正准备接受命令");                        //cdOrder=1所有线程进入等待，上面的out会打印                        cdOrder.await();                        System.out.println("线程" + Thread.currentThread().getName() + "已接受命令");                        Thread.sleep((long)(Math.random() * 10000));                        System.out.println("线程" + Thread.currentThread().getName() + "回应命令处理结果");                        //cdAnswer=3                        cdAnswer.countDown();                    }                    catch (Exception e) {                        e.printStackTrace();                    }                }            };            service.execute(runnable);        }                //主线程        try {            Thread.sleep((long)(Math.random() * 10000));                        System.out.println("线程" + Thread.currentThread().getName() + "即将发布命令");            cdOrder=1 将cdOrder减1 = 0            cdOrder.countDown();            System.out.println("线程" + Thread.currentThread().getName() + "已发送命令，正在等待结果");            //cdAnswer= 3 cdAnser进入等待            cdAnswer.await();            System.out.println("线程" + Thread.currentThread().getName() + "已收到所有响应结果");        }        catch (Exception e) {            e.printStackTrace();        }        service.shutdown();            }}