CountDownLatch的使用

妖狐艹你老母 2021-12-18 07:53 286阅读 0赞

参考自博客：[https://zapldy.iteye.com/blog/746458][https_zapldy.iteye.com_blog_746458]，感觉很好，简单易懂。

举个例子，有三个工人在为老板干活，这个老板有一个习惯，就是当三个工人把一天的活都干完了的时候，他就来检查所有工人所干的活。记住这个条件：三个工人先全部干完活，老板才检查。所以在这里用Java代码设计两个类，Worker代表工人，Boss代表老板，具体的代码实现如下：

Worker:

package com.cy.model;
    
    
    import java.util.Random;
    import java.util.concurrent.CountDownLatch;
    import java.util.concurrent.TimeUnit;
    
    public class Worker implements Runnable {
        private CountDownLatch latch;
        private String name;
    
        public Worker(CountDownLatch latch, String name) {
            this.latch = latch;
            this.name = name;
        }
    
        @Override
        public void run() {
            this.doWork();
    
            try {
                TimeUnit.SECONDS.sleep(new Random().nextInt(10));
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println(this.name + "活干完了！");
    
            this.latch.countDown();
        }
    
        private void doWork(){
            System.out.println(this.name + "正在干活!");
        }
    }

Boss:

package com.cy.model;
    
    import java.util.concurrent.CountDownLatch;
    
    public class Boss implements Runnable{
        private CountDownLatch latch;
    
        public Boss(CountDownLatch latch) {
            this.latch = latch;
        }
    
        @Override
        public void run() {
            System.out.println("老板正在等所有的工人干完活......");
    
            try {
                this.latch.await();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
    
            System.out.println("工人活都干完了，老板开始检查了！");
        }
    }

测试程序：

package com.cy.test.thread;
    
    import com.cy.model.Boss;
    import com.cy.model.Worker;
    
    import java.util.concurrent.CountDownLatch;
    import java.util.concurrent.ExecutorService;
    import java.util.concurrent.Executors;
    
    public class CountDownLatchDemo {
    
        public static void main(String[] args) {
            ExecutorService executor = Executors.newCachedThreadPool();
    
            CountDownLatch latch = new CountDownLatch(3);
            Worker w1 = new Worker(latch,"张三");
            Worker w2 = new Worker(latch,"李四");
            Worker w3 = new Worker(latch,"王五");
    
            Boss boss = new Boss(latch);
    
            executor.execute(w1);
            executor.execute(w2);
            executor.execute(w3);
            executor.execute(boss);
    
            executor.shutdown();
        }
    
    }

运行结果：

张三正在干活!
    王五正在干活!
    李四正在干活!
    老板正在等所有的工人干完活......
    张三活干完了！
    李四活干完了！
    王五活干完了！
    工人活都干完了，老板开始检查了！

当你运行CountDownLatchDemo这个对象的时候，你会发现是等所有的工人都干完了活，老板才来检查，下面是我本地机器上运行的一次结果，可以肯定的每次运行的结果可能与下面不一样，但老板检查永远是在后面的。

转载于:https://www.cnblogs.com/tenWood/p/11058528.html

[https_zapldy.iteye.com_blog_746458]: https://zapldy.iteye.com/blog/746458