CountDownLatch计数(百米赛跑模拟，子线程好比运动员，主线程好比裁判员)

import java.util.concurrent.CountDownLatch;import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;/** * CountDownLatch计数(百米赛跑模拟，子线程好比运动员，主线程好比裁判员) * @author 谭飞 * @date 2012-02-07 */public class CountDownLatchTest {/** * @param args */public static void main(String[] args) {// TODO Auto-generated method stubExecutorService threadPools = Executors.newCachedThreadPool();final CountDownLatch cdl = new CountDownLatch(1);//子线程计数final CountDownLatch cdlMain = new CountDownLatch(4);for(int i = 0; i < 4; i++){Runnable runnable = new Runnable(){@Overridepublic void run() {System.out.println("线程" + Thread.currentThread().getName()+ "准备就绪，正等待主线程命令...");try {cdl.await();//子线程计数处于等待状态，当为0时就表示完成} catch (InterruptedException e) {e.printStackTrace();}try {Thread.sleep((long)(Math.random()*10000));} catch (InterruptedException e) {e.printStackTrace();}System.out.println("线程" + Thread.currentThread().getName()+ "完成任务，等待公布结果");cdlMain.countDown();//主线程计数递减}};threadPools.execute(runnable);}//主线程操作try{Thread.sleep((long)(Math.random() * 10000));System.out.println("线程" + Thread.currentThread().getName()+ "发布命令");cdl.countDown();//子线程计数递减System.out.println("等待各个线程的答复...");cdlMain.await();System.out.println("所有的线程已经完成任务");}catch(Exception e){e.printStackTrace();}threadPools.shutdown();//关闭线程池}}