Java多线程之CountDownLatch

转 ' target='_blank'>http://blog.csdn.net/huang_xw/article/details/7090146[code=java] 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ID int 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CountDownLatch CountDownLatch 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(); } }