JAVA监控多个线程状态的一种实现

  场景：需要启动多线程处理事情，而在所有事情做完之后，需要修改系统状态；那么如何判断所有线程（事情）都做完了呢？这就需要判断所有当前运行的线程状态了。
下面是参考网上的一种写法，代码比较简洁和优雅。
  以下代码在JDK1.5编译通过！

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--做你自己的业务逻辑
			System.out.println("开始了线程：：：：" + threadsSignal.getCount());
			//线程结束时计数器减1
			threadsSignal.countDown();  
			System.out.println(Thread.currentThread().getName() + "结束. 还有"
					+ threadsSignal.getCount() + " 个线程");
		}
	}

}