java 线程 新类库中的构件 countDownLatch 使用

package org.rui.thread.newc;import java.util.Random;import java.util.concurrent.CountDownLatch;import java.util.concurrent.Executor;import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;import java.util.concurrent.TimeUnit;/** * Latch 锁存器  * 新类库中的构件 countDownLatch *  * @author lenovo *  */class TaskPortion implements Runnable {private static int counter = 0;private final int id = counter++;private static Random rand = new Random(47);private final CountDownLatch latch;public TaskPortion(CountDownLatch latch) {this.latch = latch;}@Overridepublic void run() {try {doWork();latch.countDown();} catch (InterruptedException e) {// acceptable way to exit}}// 处理业务代码public void doWork() throws InterruptedException {TimeUnit.MILLISECONDS.sleep(rand.nextInt(2000));System.out.println(this + " 完成");}public String toString() {return String.format("%1$-3d", id);}}// waits on the countDownLatchclass WaitingTask implements Runnable {private static int counter = 0;// 计数private final int id = counter++;private static Random rand = new Random(47);private final CountDownLatch latch;WaitingTask(CountDownLatch latch) {this.latch = latch;}@Overridepublic void run() {try {// 调用countDown()的任务在产生调用时并没有被阻塞，只有对await的调用会被阻塞，直至计数值到达0// 等待问题被解决的任务在这个锁存器上调用await(),将它们自已拦住，直至锁存器计数结束latch.await();System.out.println("latch 障碍被认为 " + this);} catch (InterruptedException e) {System.out.println(this + " interrupted");}}public String toString() {return String.format("waitingTask %1$-3d", id);}}/** * TaskPortio将随机地休眠一段时间，以模拟这部分工作的完成，而WaitingTask表示系统中等待的部分，它要等待到问题的初始部分成完为止， * 所有的任务都使用了在main中定义同一个单一的counDownLacth *  * @author lenovo *  */public class CountDownLatchDemo {static final int SIZE = 100;public static void main(String[] args) throws InterruptedException {ExecutorService exec = Executors.newCachedThreadPool();CountDownLatch latch = new CountDownLatch(SIZE);// 都必须共享一个countDownLatch对象for (int i = 0; i < 10; i++) {exec.execute(new WaitingTask(latch));// 这个要等待 latch上面的为0时才会执行}for (int i = 0; i < SIZE; i++) {exec.execute(new TaskPortion(latch));}// latch.await();System.out.println("launched all tasks");exec.shutdown();// quit when all task complete}}/**output:launched all tasks43  完成95  完成99  完成36  完成94  完成11  完成....12  完成1   完成27  完成98  完成13  完成72  完成71  完成2   完成45  完成92  完成31  完成14  完成17  完成6   完成97  完成....80  完成....56  完成85  完成61  完成30  完成....3   完成93  完成81  完成78  完成73  完成44  完成82  完成49  完成64  完成83  完成16  完成latch 障碍被认为 waitingTask 2  latch 障碍被认为 waitingTask 0  latch 障碍被认为 waitingTask 4  latch 障碍被认为 waitingTask 1  latch 障碍被认为 waitingTask 5  latch 障碍被认为 waitingTask 3  latch 障碍被认为 waitingTask 7  latch 障碍被认为 waitingTask 6  latch 障碍被认为 waitingTask 9  latch 障碍被认为 waitingTask 8  */