Semaphore、CyclicBarrier、CountDownLatch

一、CountDownLatch

package flowcontrol.countdownlatch;import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;/*** 描述： 工厂中，质检，5个工人检查，所有人都认为通过，才通过*/
public class CountDownLatchDemo1 {
    public static void main(String[] args) throws InterruptedException {
    CountDownLatch latch = new CountDownLatch(5);ExecutorService service = Executors.newFixedThreadPool(5);for (int i = 0; i < 5; i++) {
    final int no = i + 1;Runnable runnable = new Runnable() {
    @Overridepublic void run() {
    try {
    Thread.sleep((long) (Math.random() * 10000));System.out.println("No." + no + "完成了检查。");} catch (InterruptedException e) {
    e.printStackTrace();} finally {
    latch.countDown();}}};service.submit(runnable);}System.out.println("等待5个人检查完.....");latch.await();System.out.println("所有人都完成了工作，进入下一个环节。");}
}

package flowcontrol.countdownlatch;import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;/*** 描述： 模拟100米跑步，5名选手都准备好了，只等裁判员一声令下，所有人同时开始跑步。*/
public class CountDownLatchDemo2 {
    public static void main(String[] args) throws InterruptedException {
    CountDownLatch begin = new CountDownLatch(1);ExecutorService service = Executors.newFixedThreadPool(5);for (int i = 0; i < 5; i++) {
    final int no = i + 1;Runnable runnable = new Runnable() {
    @Overridepublic void run() {
    System.out.println("No." + no + "准备完毕，等待发令枪");try {
    begin.await();System.out.println("No." + no + "开始跑步了");} catch (InterruptedException e) {
    e.printStackTrace();}}};service.submit(runnable);}//裁判员检查发令枪...Thread.sleep(5000);System.out.println("发令枪响，比赛开始！");begin.countDown();}
}

运行结果

package flowcontrol.countdownlatch;import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;/*** 描述： 模拟100米跑步，5名选手都准备好了，只等裁判员一声令下，所有人同时开始跑步。当所有人都到终点后，比赛结束。*/
public class CountDownLatchDemo1And2 {
    public static void main(String[] args) throws InterruptedException {
    CountDownLatch begin = new CountDownLatch(1);CountDownLatch end = new CountDownLatch(5);ExecutorService service = Executors.newFixedThreadPool(5);for (int i = 0; i < 5; i++) {
    final int no = i + 1;Runnable runnable = new Runnable() {
    @Overridepublic void run() {
    System.out.println("No." + no + "准备完毕，等待发令枪");try {
    begin.await();System.out.println("No." + no + "开始跑步了");Thread.sleep((long) (Math.random() * 10000));System.out.println("No." + no + "跑到终点了");} catch (InterruptedException e) {
    e.printStackTrace();} finally {
    end.countDown();}}};service.submit(runnable);}//裁判员检查发令枪...Thread.sleep(5000);System.out.println("发令枪响，比赛开始！");begin.countDown();end.await();System.out.println("所有人到达终点，比赛结束");}
}

二、Semaohore

package flowcontrol.semaphore;import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Semaphore;/*** 描述： 演示Semaphore用法*/
public class SemaphoreDemo {
    static Semaphore semaphore = new Semaphore(5, true);public static void main(String[] args) {
    ExecutorService service = Executors.newFixedThreadPool(50);for (int i = 0; i < 100; i++) {
    service.submit(new Task());}service.shutdown();}static class Task implements Runnable {
    @Overridepublic void run() {
    try {
    semaphore.acquire(3);} catch (InterruptedException e) {
    e.printStackTrace();}System.out.println(Thread.currentThread().getName() + "拿到了许可证");try {
    Thread.sleep(2000);} catch (InterruptedException e) {
    e.printStackTrace();}System.out.println(Thread.currentThread().getName() + "释放了许可证");semaphore.release(2);}}
}

三、Cyclicbarrier

package flowcontrol.cyclicbarrier;import java.util.concurrent.BrokenBarrierException;
import java.util.concurrent.CyclicBarrier;/*** 描述： 演示CyclicBarrier*/
public class CyclicBarrierDemo {
    public static void main(String[] args) {
    CyclicBarrier cyclicBarrier = new CyclicBarrier(5, new Runnable() {
    @Overridepublic void run() {
    System.out.println("所有人都到场了， 大家统一出发！");}});for (int i = 0; i < 10; i++) {
    new Thread(new Task(i, cyclicBarrier)).start();}}static class Task implements Runnable{
    private int id;private CyclicBarrier cyclicBarrier;public Task(int id, CyclicBarrier cyclicBarrier) {
    this.id = id;this.cyclicBarrier = cyclicBarrier;}@Overridepublic void run() {
    System.out.println("线程" + id + "现在前往集合地点");try {
    Thread.sleep((long) (Math.random()*10000));System.out.println("线程"+id+"到了集合地点，开始等待其他人到达");cyclicBarrier.await();System.out.println("线程"+id+"出发了");} catch (InterruptedException e) {
    e.printStackTrace();} catch (BrokenBarrierException e) {
    e.printStackTrace();}}}}

四、总结