CountdownLatch

最新推荐文章于 2025-08-21 16:15:25 发布

转载最新推荐文章于 2025-08-21 16:15:25 发布 · 44 阅读

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原文链接：http://www.cnblogs.com/alamps/p/8196454.html

文章标签：

#java

本文通过一个具体示例展示了如何使用 Java 的 CountDownLatch 类来协调多个线程的运行。主线程会在启动若干子线程后，等待这些子线程完成任务并返回结果。CountDownLatch 在并发编程中用于解决一个线程等待一组线程完成的问题。

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

public class CountdownLatchTest {

    public static void main(String[] args) {
        ExecutorService service = Executors.newCachedThreadPool();
        final CountDownLatch cdOrder = new CountDownLatch(1);
        final CountDownLatch cdAnswer = new CountDownLatch(3);        
        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);
        }        
        try {
            Thread.sleep((long)(Math.random()*10000));
        
            System.out.println("线程" + Thread.currentThread().getName() + 
                    "即将发布命令");                        
            cdOrder.countDown();
            System.out.println("线程" + Thread.currentThread().getName() + 
            "已发送命令，正在等待结果");    
            cdAnswer.await();
            System.out.println("线程" + Thread.currentThread().getName() + 
            "已收到所有响应结果");    
        } catch (Exception e) {
            e.printStackTrace();
        }                
        service.shutdown();

    }
}