java线程并发countdownlatch类使用示例

package com.yao;

import java.util.concurrent.countdownlatch;
import java.util.concurrent.executorservice;
import java.util.concurrent.executors;

/**
 * countdownlatch是个计数器，它有一个初始数，
 * 等待这个计数器的线程必须等到计数器倒数到零时才可继续。
 */
public class countdownlatchtest {

 /**
  * 初始化组件的线程
  */
 public static class componentthread implements runnable {
  // 计数器
  countdownlatch latch;
  // 组件id
  int id;

  // 构造方法
  public componentthread(countdownlatch latch, int id) {
   this.latch = latch;
   this.id = id;
  }

  public void run() {
   // 初始化组件
   system.out.println("initializing component " + id);
   try {
    thread.sleep(500 * id);
   } catch (interruptedexception e) {
   }
   system.out.println("component " + id + " initialized!");
   //将计数器减一
   latch.countdown();
  }
 }

 /**
  * 启动服务器
  */
 public static void startserver() throws exception {
  system.out.println("server is starting.");
  //初始化一个初始值为3的countdownlatch
  countdownlatch latch = new countdownlatch(3);
  //起3个线程分别去启动3个组件
  executorservice service = executors.newcachedthreadpool();
  service.submit(new componentthread(latch, 1));
  service.submit(new componentthread(latch, 2));
  service.submit(new componentthread(latch, 3));
  service.shutdown();

  //等待3个组件的初始化工作都完成
  latch.await();

  //当所需的三个组件都完成时，server就可继续了
  system.out.println("server is up!");
 }

 public static void main(string[] args) throws exception {
  countdownlatchtest.startserver();
 }
}