java 线程 新类库中的构件 CyclicBarrier使用

package org.rui.thread.newc;import java.util.ArrayList;import java.util.List;import java.util.Random;import java.util.concurrent.BrokenBarrierException;import java.util.concurrent.CyclicBarrier;import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;import java.util.concurrent.TimeUnit;/** * 赛马游戏 CyclicBarrier *  * @author lenovo *  */class Horse implements Runnable {private static int counter = 0;private final int id = counter++;private int strides = 0;private static Random rand = new Random(47);private static CyclicBarrier barrier;public Horse(CyclicBarrier b) {barrier = b;}public synchronized int getStrides() {return strides;}@Overridepublic void run() {try {while (!Thread.interrupted()) {synchronized (this) {//每场比赛都会加上随机 跨过的数字 0,1 or 2strides += rand.nextInt(3);// produces 0,1 or 2}// 等待所有的马都准备完毕，当所有的马向前移动时，cyclicBarrier将自动调用runnable栅栏动作任务，按顺序显示马和终点的位置barrier.await();}} catch (InterruptedException e) {} catch (BrokenBarrierException e) {throw new RuntimeException(e);}}public String toString() {return "Horse" + id + " ";}// 轨道public String tracks() {StringBuilder s = new StringBuilder();for (int i = 0; i < getStrides(); i++) {s.append("*");}s.append(id);return s.toString();}}public class HorseRace {static final int FINISH_LINE = 75;// 结束 行private List<Horse> horses = new ArrayList<Horse>();private ExecutorService exec = Executors.newCachedThreadPool();private CyclicBarrier barrier;public HorseRace(int nHorses, final int pause) {barrier = new CyclicBarrier(nHorses/*等待的数量*/, new Runnable() {@Overridepublic void run() {//打印信息 StringBuilder sb = new StringBuilder();for (int i = 0; i < FINISH_LINE; i++) {sb.append("=");// 赛马场上的栅栏}System.out.println(sb);for (Horse horse : horses) {System.out.println(horse.tracks());}for (Horse horse : horses) {//System.out.println("strides:@@@@@@@" + horse.getStrides());if (horse.getStrides() >= FINISH_LINE) {//System.out.println(horse + "赢得!");exec.shutdownNow();return;}}try {TimeUnit.MILLISECONDS.sleep(pause);} catch (InterruptedException e) {System.out.println("barrier-action sleep interrupted");}}});// 一旦所有的马都越过了栅栏，它就会自动地为下一回合比赛做好准备for (int i = 0; i < nHorses; i++) {Horse horse = new Horse(barrier);//每个马都分配一个barrierhorses.add(horse);exec.execute(horse);}}/** * main *  * @param args */public static void main(String[] args) {int nHorses = 7; //指定马的数量int pause = 200;//停顿时间String[] arg = {};if (arg.length > 0) {// optional argumentint n = new Integer(arg[0]);nHorses = n > 0 ? n : nHorses;}if (arg.length > 1) {// optional argumentint p = new Integer(arg[1]);pause = p > -1 ? p : pause;}// 竞赛new HorseRace(nHorses, pause);}}/** ===========================================================================**0**1*2**3*4**5*6===========================================================================**0***1*2**3*4***5***6===========================================================================***0****1***2***3**4*****5****6===========================================================================*****0****1*****2****3**4******5****6===========================================================================******0****1******2*****3****4******5*****6===========================================================================******0******1******2******3****4*******5*****6===========================================================================*******0******1*******2******3*****4********5*******6===========================================================================********0******1********2*******3*******4*********5*********6===========================================================================********0******1*********2*******3*********4*********5*********6===========================================================================**********0*******1**********2********3*********4***********5*********6===========================================================================**********0*******1************2*********3*********4*************5*********6===========================================================================************0*******1*************2***********3**********4***************5***********6===========================================================================************0********1*************2*************3***********4***************5*************6===========================================================================**************0********1*************2*************3*************4......

...此处省略打印线===========================================================================**********************************************************************0*******************************************************1******************************************************************2***********************************************************************3***********************************************************************4***********************************************************************5*************************************************************6===========================================================================***********************************************************************0*******************************************************1*******************************************************************2*************************************************************************3***********************************************************************4*************************************************************************5***************************************************************6===========================================================================************************************************************************0********************************************************1*******************************************************************2***************************************************************************3***********************************************************************4***************************************************************************5****************************************************************6Horse3 赢得! */

一个容易理解的张孝祥老师讲解例子 

package test;import java.util.concurrent.BrokenBarrierException;import java.util.concurrent.CyclicBarrier;import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;/** * CyclicBarrier 应用 * @author lenovo * */public class CyclicBarrierTest {public static void main(String[] args) {ExecutorService service = Executors.newCachedThreadPool();final CyclicBarrier cb = new CyclicBarrier(3); // 三个线程同时到达for (int i = 0; i < 3; i++) {Runnable runnable = new Runnable() {public void run() {try {Thread.sleep((long) (Math.random() * 10000));System.out.println("线程"+ Thread.currentThread().getName()+ "即将到达集合地点1，当前已有"+ (cb.getNumberWaiting() + 1)+ "个已到达"+ (cb.getNumberWaiting() == 2 ? "都到齐了，继续走啊": "正在等候"));try {cb.await();} catch (BrokenBarrierException e) {e.printStackTrace();}Thread.sleep((long) (Math.random() * 10000));System.out.println("线程"+ Thread.currentThread().getName()+ "即将到达集合地点2，当前已有"+ (cb.getNumberWaiting() + 1)+ "个已到达"+ (cb.getNumberWaiting() == 2 ? "都到齐了，继续走啊": "正在等候"));try {cb.await();} catch (BrokenBarrierException e) {e.printStackTrace();}Thread.sleep((long) (Math.random() * 10000));System.out.println("线程"+ Thread.currentThread().getName()+ "即将到达集合地点3，当前已有"+ (cb.getNumberWaiting() + 1)+ "个已到达"+ (cb.getNumberWaiting() == 2 ? "都到齐了，继续走啊": "正在等候"));try {cb.await();} catch (BrokenBarrierException e) {e.printStackTrace();}} catch (InterruptedException e) {e.printStackTrace();}}};service.execute(runnable);}service.shutdown();}}/** * output:线程pool-1-thread-3即将到达集合地点1，当前已有1个已到达正在等候线程pool-1-thread-1即将到达集合地点1，当前已有2个已到达正在等候线程pool-1-thread-2即将到达集合地点1，当前已有3个已到达都到齐了，继续走啊线程pool-1-thread-2即将到达集合地点2，当前已有1个已到达正在等候线程pool-1-thread-1即将到达集合地点2，当前已有2个已到达正在等候线程pool-1-thread-3即将到达集合地点2，当前已有3个已到达都到齐了，继续走啊线程pool-1-thread-3即将到达集合地点3，当前已有1个已到达正在等候线程pool-1-thread-2即将到达集合地点3，当前已有2个已到达正在等候线程pool-1-thread-1即将到达集合地点3，当前已有3个已到达都到齐了，继续走啊 */