并发包java.util.concurrent.CountDownLatch

Posted 2020-09-19 安静

/**
 * 
 * @描述: 倒计时器 .
 * 犹如倒计时计数器，调用CountDownLatch对象的countDown方法就将计数器减1，当计算器为0的时候
 * 则所有等待者或单个等待者开始执行
 * @作者: Wnj .
 * @创建时间: 2017年5月15日 .
 * @版本: 1.0 .
 */
public class CountdownLatchTest {
    
    public static void main(String[] args) {
        ExecutorService service = Executors.newCachedThreadPool();
        
        //吹口哨
        final CountDownLatch cdOrder = new CountDownLatch(1);
        
        //等待结果
        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=1所有线程进入等待，上面的out会打印
                        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=3
                        cdAnswer.countDown();
                    }
                    catch (Exception e) {
                        e.printStackTrace();
                    }
                }
            };
            service.execute(runnable);
        }
        
        //主线程
        try {
            Thread.sleep((long)(Math.random() * 10000));
            
            System.out.println("线程" + Thread.currentThread().getName() + "即将发布命令");
            ////cdOrder=1 将cdOrder减1 = 0
            cdOrder.countDown();
            System.out.println("线程" + Thread.currentThread().getName() + "已发送命令，正在等待结果");
            //cdAnswer= 3 cdAnser进入等待
            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();
        
    }
}