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 [J2SE相关]JDK1.5新特性--java.util.concurrent CyclicBarrier(2)
文章收藏, 网上资源, 软件技术, 电脑与网络
李小白 发表于 2007/7/18 17:06:59 |
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lhwork 发表于 2006-12-11 11:15:57
在实际应用中，有时候需要多个线程同时工作以完成同一件事情，而且在完成过程中，往往会等待其他线程都完成某一阶段后再执行，等所有线程都到达某一个阶段后再统一执行。
比如有几个旅行团需要途经深圳、广州、韶关、长沙最后到达武汉。旅行团中有自驾游的，有徒步的，有乘坐旅游大巴的；这些旅行团同时出发，并且每到一个目的地，都要等待其他旅行团到达此地后再同时出发，直到都到达终点站武汉。
这时候CyclicBarrier就可以派上用场。CyclicBarrier最重要的属性就是参与者个数，另外最要方法是await()。当所有线程都调用了await()后，就表示这些线程都可以继续执行，否则就会等待。
package concurrent;import java.text.SimpleDateFormat;import java.util.Date;import java.util.concurrent.BrokenBarrierException;import java.util.concurrent.CyclicBarrier;import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;public class TestCyclicBarrier { // 徒步需要的时间: Shenzhen, Guangzhou, Shaoguan, Changsha, Wuhan private static int[] timeWalk = { 5, 8, 15, 15, 10 }; // 自驾游 private static int[] timeSelf = { 1, 3, 4, 4, 5 }; // 旅游大巴 private static int[] timeBus = { 2, 4, 6, 6, 7 }; static String now() { SimpleDateFormat sdf = new SimpleDateFormat("HH:mm:ss"); return sdf.format(new Date()) + ": "; } static class Tour implements Runnable { private int[] times; private CyclicBarrier barrier; private String tourName; public Tour(CyclicBarrier barrier, String tourName, int[] times) { this.times = times; this.tourName = tourName; this.barrier = barrier; } public void run() { try { Thread.sleep(times[0] * 1000); System.out.println(now() + tourName + " Reached Shenzhen"); barrier.await(); Thread.sleep(times[1] * 1000); System.out.println(now() + tourName + " Reached Guangzhou"); barrier.await(); Thread.sleep(times[2] * 1000); System.out.println(now() + tourName + " Reached Shaoguan"); barrier.await(); Thread.sleep(times[3] * 1000); System.out.println(now() + tourName + " Reached Changsha"); barrier.await(); Thread.sleep(times[4] * 1000); System.out.println(now() + tourName + " Reached Wuhan"); barrier.await(); } catch (InterruptedException e) { } catch (BrokenBarrierException e) { } } } public static void main(String[] args) { // 三个旅行团 CyclicBarrier barrier = new CyclicBarrier(3); ExecutorService exec = Executors.newFixedThreadPool(3); exec.submit(new Tour(barrier, "WalkTour", timeWalk)); exec.submit(new Tour(barrier, "SelfTour", timeSelf)); exec.submit(new Tour(barrier, "BusTour", timeBus)); exec.shutdown(); }} 运行结果：00:02:25: SelfTour Reached Shenzhen00:02:25: BusTour Reached Shenzhen00:02:27: WalkTour Reached Shenzhen00:02:30: SelfTour Reached Guangzhou00:02:31: BusTour Reached Guangzhou00:02:35: WalkTour Reached Guangzhou00:02:39: SelfTour Reached Shaoguan00:02:41: BusTour Reached Shaoguan |
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