CountDownLatch的使用(倒计时计数器)

àì夳堔傛蜴生んèń 2022-01-15 14:19 221阅读 0赞

countDown()将计数器减一

await()等待计数器值为0,当到达0时所有等待者开始执行

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(); 
            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(); 
    
        }
    }

转载于:https://blog.51cto.com/tianxingzhe/1716849