import java.util.concurrent.CountDownLatch;
import java.util.concurrent.Executor;
import java.util.concurrent.Executors;

/**
 * 测试监控类
 * 
 * @author
 * 
 */
public class WatchThread {

 /**
 * 测试函数
 * 
 * @throws InterruptedException
 */
 public void testThread() throws InterruptedException {
 int threadNum = 10;
 // 初始化countDown
 CountDownLatch threadSignal = new CountDownLatch(threadNum);
 // 创建固定长度的线程池
 Executor executor = Executors.newFixedThreadPool(threadNum);
 for (int i = 0; i < threadNum; i++) { // 开threadNum个线程
  Runnable task = new TestThread(threadSignal);
  // 执行
  executor.execute(task);
 }
 threadSignal.await(); // 等待所有子线程执行完
 // do work
 System.out.println(Thread.currentThread().getName() + "+++++++结束.");
 }

 /**
 * 测试函数
 */
 public static void main(String[] args) throws InterruptedException {
 WatchThread test = new WatchThread();
 test.testThread();
 }

 /**
 * 
 * @author jill
 * 
 */
 private class TestThread implements Runnable {
 private CountDownLatch threadsSignal;

 public TestThread(CountDownLatch threadsSignal) {
  this.threadsSignal = threadsSignal;
 }

 public void run() {
  System.out.println(Thread.currentThread().getName() + "开始...");
  // do shomething
  System.out.println("开始了线程：：：：" + threadsSignal.getCount());
  // 线程结束时计数器减1
  threadsSignal.countDown();  //这句代码 建议放在 finally里执行 
  System.out.println(Thread.currentThread().getName() + "结束. 还有"
   + threadsSignal.getCount() + " 个线程");
 }
 }

}