一个同步辅助类，在完成一组正在其他线程中执行的操作之前，它允许一个或多个线程一直等待。
下面使用了两个倒计数锁存器：即一个等待另一个的完成
代码语言：javascript复制import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
public class CountDownLatchTest {
/**
* @param args
*/
public static void main(String[] args) {
ExecutorService ThreadPool = 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() {
@Override
public void run() {
try {
System.out.println("线程 " Thread.currentThread().getName() " 正在等待接受命令");
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 (InterruptedException e) {
e.printStackTrace();
}
}
};
ThreadPool.execute(runnable);
}
try {
Thread.sleep((long)Math.random()*10000);
System.out.println("线程 " Thread.currentThread().getName() " 正在等待发布命令");
cdOrder.countDown();
cdAnswer.await();
System.out.println("线程 " Thread.currentThread().getName() " 已发布命令，正在等待结果");
System.out.println("所有命令都处理完");
} catch (InterruptedException e) {
e.printStackTrace();
}
ThreadPool.shutdown();
}
}
