package com.ljq.test.thread;
 
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
 
public class CountdownLatchTest {
 
  public static void main(String[] args) {
    ExecutorService service = Executors.newCachedThreadPool();
    //裁判发布命令的计数器，计数器为0，运动员就跑
    final CountDownLatch cdOrder = new CountDownLatch(1);
    //运动员跑到终点的计数器，为0裁判宣布结果
    final CountDownLatch cdAnswer = new CountDownLatch(3); 
     
    //产生3个运动员
    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.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.countDown();           
          } catch (Exception e) {
            e.printStackTrace();
          }       
        }
      };
      service.execute(runnable); //运动员开始任务
    }   
     
     
    try {
      //裁判休息一会 再发布命令
      Thread.sleep((long)(Math.random()*10000));
     
      System.out.println("线程" + Thread.currentThread().getName() + "即将发布命令");          
      cdOrder.countDown(); //命令计数器置为0，发布命令
      System.out.println("线程" + Thread.currentThread().getName() + "已发送命令，正在等待结果"); 
      cdAnswer.await(); //等待所有运动员，计数器为0 所有运动员到位
      System.out.println("线程" + Thread.currentThread().getName() + "已收到所有响应结果"); 
    } catch (Exception e) {
      e.printStackTrace();
    }       
    service.shutdown();
 
  }
}

线程pool-1-thread-3正准备接受命令
线程pool-1-thread-1正准备接受命令
线程pool-1-thread-2正准备接受命令
线程main即将发布命令
线程main已发送命令，正在等待结果
线程pool-1-thread-2已接受命令
线程pool-1-thread-1已接受命令
线程pool-1-thread-3已接受命令
线程pool-1-thread-3回应命令处理结果
线程pool-1-thread-2回应命令处理结果
线程pool-1-thread-1回应命令处理结果
线程main已收到所有响应结果