CountDownLatch和CyclicBarrier初步学习
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CountDownLatch用法：
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需要调用CountDownLatch的await()方法来等待计数器归零（线程全部签到）。调用CountDownLatch的countDown()方法让计数器减一（签到）
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package com.tch.test.concurrent.test;import java.util.Random;import java.util.concurrent.CountDownLatch;import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;public class CountDownLatchTest {/** 线程数 */private int num = 3;private Random random = new Random();/** 开始运行的计数器 */private CountDownLatch begin = new CountDownLatch(1);/** 所有线程签到的计数器 */private CountDownLatch end = new CountDownLatch(num);private ExecutorService executor = Executors.newFixedThreadPool(5);public static void main(String[] args) {new CountDownLatchTest().test();}private void test() {try {doTask();System.out.println( "开始 ");//发出开始运行的信号begin.countDown();//主线程等待end计数器减到0，也就是所有线程都完成签到(end.countDown())end.await();System.out.println("结束 "+System.currentTimeMillis());executor.shutdown();} catch (InterruptedException e) {e.printStackTrace();}}private void doTask(){for(int i=0;i<num;i++){executor.execute(new Task(i));}}class Task implements Runnable{private int id;public Task(int id){this.id = id;}@Overridepublic void run() {try {//等待begin的计数器减到0，导致当前线程进入阻塞状态begin.await();Thread.sleep(random.nextInt(1500));System.out.println("线程"+id+"结束"+System.currentTimeMillis());//向end计数器报到，end计时器减一end.countDown();//等待end计数器减到0，也就是等待所有线程都完成end.await();System.out.println("全部线程结束 "+System.currentTimeMillis());} catch (InterruptedException e) {e.printStackTrace();}}}}?
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CyclicBarrier用法：
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调用CyclicBarrier的await()方法来签到 并且 等待其它线程全部签到完成。
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package com.tch.test.concurrent.test;import java.util.Random;import java.util.concurrent.CyclicBarrier;import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;public class CyclicBarrierTest {private CyclicBarrier barrier;/** 线程数 */private int num = 3;private Random random = new Random();private ExecutorService executor = Executors.newFixedThreadPool(5);public static void main(String[] args) {new CyclicBarrierTest().test();}private void test() {barrier = new CyclicBarrier(num, new Runnable() {@Overridepublic void run() {System.out.println("全部签到完成"+System.currentTimeMillis());System.out.println(barrier.getNumberWaiting()+" "+barrier.getParties());//barrier.reset();System.out.println("--------------重新开始------------");doTask();}});doTask();barrier.reset();//executor.shutdown();}//barrier.reset();private void doTask(){for(int i=0;i<num;i++){executor.execute(new Task(i));}}class Task implements Runnable{private int id;public Task(int id){this.id = id;}@Overridepublic void run() {try {Thread.sleep(random.nextInt(1500));System.out.println("线程"+id+"结束"+System.currentTimeMillis());barrier.await();} catch (Exception e) {e.printStackTrace();}}}}?
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