并发工具类CountDownLatch

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本文介绍了一个使用Java的CountDownLatch类实现的并发控制示例。CountDownLatch允许一个或多个线程等待其他线程完成操作。通过两个不同的线程类，InitThread和BusiThread，演示了CountDownLatch的基本用法。InitThread类用于模拟初始化线程，完成准备工作后调用countDown()方法。BusiThread类则在所有初始化线程完成前被阻塞，之后执行业务逻辑。

import java.util.concurrent.CountDownLatch;

/**
 *并发工具类CountDownLatch
 */
public class UseCountDownLatch {
   static CountDownLatch latch = new CountDownLatch(3);
   //初始化线程
    private static class InitThread implements Runnable{
        @Override
        public void run() {
           System.out.println("Thread_"+Thread.currentThread().getId()
                 +" ready init work......");
           latch.countDown();//初始化线程完成工作了，countDown方法只扣减一次；
            for(int i =0;i<2;i++) {
               System.out.println("Thread_"+Thread.currentThread().getId()
                     +" ........continue do its work");
            }
        }
    }
    
    //业务线程
    private static class BusiThread implements Runnable{
        @Override
        public void run() {
           try {
            latch.await();
         } catch (InterruptedException e) {
            e.printStackTrace();
         }
            for(int i =0;i<3;i++) {
               System.out.println("BusiThread_"+Thread.currentThread().getId()
                     +" do business-----");
            }
        }
    }

    public static void main(String[] args) throws InterruptedException {
        new Thread(new BusiThread()).start();
        for(int i=0;i<3;i++){
            Thread thread = new Thread(new InitThread());
            thread.start();
        }
        latch.await();
        System.out.println("Main do its work........");
    }
}