JAVA多线程之CountDownLatch

来源：http://blog.csdn.net/huang_xw/article/details/7090146

package com.fei;import java.util.concurrent.CountDownLatch;import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;/** * CountDownLatch是个计数器，它有一个初始数， * 等待这个计数器的线程必须等到计数器倒数到零时才可继续。 */public class CountDownLatchTest {/** * 初始化组件的线程 */public static class ComponentThread implements Runnable {// 计数器CountDownLatch latch;// 组件IDint ID;// 构造方法public ComponentThread(CountDownLatch latch, int ID) {this.latch = latch;this.ID = ID;}public void run() {// 初始化组件System.out.println("Initializing component " + ID);try {Thread.sleep(500 * ID);} catch (InterruptedException e) {}System.out.println("Component " + ID + " initialized!");//将计数器减一latch.countDown();}}/** * 启动服务器 */public static void startServer() throws Exception {System.out.println("Server is starting.");//初始化一个初始值为3的CountDownLatchCountDownLatch latch = new CountDownLatch(3);//起3个线程分别去启动3个组件ExecutorService service = Executors.newCachedThreadPool();service.submit(new ComponentThread(latch, 1));service.submit(new ComponentThread(latch, 2));service.submit(new ComponentThread(latch, 3));service.shutdown();//等待3个组件的初始化工作都完成latch.await();//当所需的三个组件都完成时，Server就可继续了System.out.println("Server is up!");}public static void main(String[] args) throws Exception {CountDownLatchTest.startServer();}}