CountDownLatch的使用方法

CountDownLatch的使用方法

/**
CountDownLatch类是一个同步计数器（同步辅助类）,构造时传入int参数,该参数就是计数器的初始值，每调用一次countDown()方法，计数器减1,
计数器大于0 时，await()方法会阻塞程序继续执行
CountDownLatch如其所写，是一个倒计数的锁存器，当计数减至0时触发特定的事件。利用这种特性，可以让主线程等待子线程的结束
*/

主要方法
 public CountDownLatch(int count);   // 构造方法参数指定了计数的次数
 public void countDown();  // 当前线程调用此方法，则计数减一
 public void await() throws InterruptedException   // 调用此方法会一直阻塞当前线程，直到计时器的值为0

package CountDownLatchTest;import java.util.concurrent.CountDownLatch;import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;public class CountDownLatchDemoTest {/** * @param args */public static void main(String[] args) {CountDownLatch countDownLatch = new CountDownLatch(5);System.out.println("start...");try {ExecutorService eService = Executors.newFixedThreadPool(3);for(int i = 0 ; i < 5 ; i ++){eService.execute(new CountDownLatchDemoTest().new WorkRunnable(countDownLatch));}countDownLatch.await(); // 这里开始阻塞，一直等到countDownLatch的值为0}catch (InterruptedException e) {e.printStackTrace();System.out.println(e.toString());}System.out.println("end...");}class WorkRunnable implements Runnable{CountDownLatch countDownLatch = null;public WorkRunnable(CountDownLatch countDownLatch) {this.countDownLatch = countDownLatch;}@Overridepublic void run() {System.out.println("ThreadName = " + Thread.currentThread().getName());countDownLatch.countDown();  // countDownLatch的值减一}}}