用ExecutorService&cyclicBarrier&countDownLatch实现...

这个博客介绍的不错：http://my.oschina.net/jielucky/blog/157946

http://my.oschina.net/adwangxiao/blog/110188

我再顺着这个博客往下写：

赛马是个不错的多线程场景，包括所有赛马都准备好，然后指挥官喊预备跑部分，然后所有赛马跑到了，关闭所有跑道两部分，这个场景可以很好的运用多线程。如下图所示.

![在此输入图片描述][1]

package com.xue.gang.barrier;

import java.util.concurrent.BrokenBarrierException;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.CyclicBarrier;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class CyclicBarrierMutiRunner {

public static void main(String args[]) throws InterruptedException{

    final int  size = 10;

    ExecutorService executorService = Executors.newCachedThreadPool();
    /**用户指挥官部分*/
    CyclicBarrier cyclicBarrier = new CyclicBarrier(size,new Commander());

    /**用户关闭线程池*/
    CountDownLatch countDownLatch = new CountDownLatch(size);
    for(int i =1;i<=size;i++){
        executorService.execute(new Horse(cyclicBarrier,countDownLatch,i+"——号"));
    }

    countDownLatch.await();
    executorService.shutdown();
}


/**指挥官*/
static class Commander implements Runnable{

    public Commander() {
        super();
        // TODO Auto-generated constructor stub
    }

    public void run() {

        System.out.println("---------->预备...开始..跑...!!!!!!!!!!!!!!!!!!!!!!!!");

    }
}
/**马* */
static class Horse implements Runnable{

    /**用于指挥官**/
    private CyclicBarrier cyclicBarrier;

    /**用于线程池子*/
    private CountDownLatch countDownLatch;

    private String horseName;



    public Horse(CyclicBarrier cyclicBarrier,
            CountDownLatch countDownLatch, String horseName) {
        super();
        this.cyclicBarrier = cyclicBarrier;
        this.countDownLatch = countDownLatch;
        this.horseName = horseName;
    }



    public void run() {

        System.out.println("报告，"+this.horseName+":在去赛场的路上...");
        try {
            //等待一个随机数
            Thread.sleep((long)Math.random()*10000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("报告，"+this.horseName+":准备好了，等待其它马准备好了，一起跑...");
        try {
            //通知其它线程，准备好了
            this.cyclicBarrier.await();
        } catch (InterruptedException e) {
            e.printStackTrace();
        } catch (BrokenBarrierException e) {
            e.printStackTrace();
        }
        System.out.println("报告，"+this.horseName+":飞奔中...");
        //报告跑到了..
        this.countDownLatch.countDown();
    }
}

}

参考：http://my.oschina.net/jielucky/blog/157946