多线程辅助类之CountDownLatch(三)

CountDownLatch信号灯是一个同步辅助类，在完成一组正在其他线程中执行的操作之前，它允许一个或多个线程一直等待。它可以实现多线程的同步互斥功能，和wait和notify方法实现功能类似，具体的实现代码如下：

package face.thread.CountDownLatch;

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.concurrent.CountDownLatch;

public class CountDownLatchDemo3 {
	
	public static void main(String[] args) {
		
		int capaCity = 3;
		final SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");  
		final CountDownLatch start = new CountDownLatch(1);
		final CountDownLatch startAnswer = new CountDownLatch(capaCity);
		
		final CountDownLatch end = new CountDownLatch(1);
		final CountDownLatch endAnswer = new CountDownLatch(capaCity);
		
		for(int i=0; i<capaCity; i++){
			new Thread(new Runnable() {
				public void run() {
					System.out.println(Thread.currentThread().getName() +"运动员准备就绪," + sdf.format(new Date()));
					try {
						startAnswer.countDown();
						start.await();
						Thread.sleep(1000);
					} catch (InterruptedException e) {
						e.printStackTrace();
					}finally{
						System.out.println(Thread.currentThread().getName() +"运动员结束比赛," + sdf.format(new Date()));
						endAnswer.countDown();
					}
				}
			}).start();
		}
		
		try {
			startAnswer.await();
			System.out.println("比赛开始：" + sdf.format(new Date()));
			start.countDown();
			
			endAnswer.await();
		} catch (Exception e) {
			e.printStackTrace();
		}finally{
			System.out.println("比赛结束：" + sdf.format(new Date()));
		}
	}
}

具体的说明参照Jdk Api，参照此例子加以理解