线程协作工具类【CountDownLatch倒数门闩、Semaphore信号量、CyclicBarrier循环栏栅、Condition接口】

转自 极客时间

线程协作工具类就是帮助程序员更容易的让线程之间进行协作，来完成某个业务功能。

CountDownLatch倒数门闩

import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;
/*** CountDownLatch案例：6个程序猿加班* 当计数器的值变为0时，因await方法阻塞的线程会被唤醒，继续执行*/
public class Demo11CountDownLatch {public static void main(String[] args) throws InterruptedException {//计数门闩CountDownLatch countDownLatch = new CountDownLatch(6);for (int i = 1; i <= 6; i++) {new Thread(()->{try {TimeUnit.SECONDS.sleep(5);} catch (InterruptedException e) {e.printStackTrace(); }System.out.println(Thread.currentThread().getName() + "\t上完班，离开公司");countDownLatch.countDown();}, String.valueOf(i)).start();}new Thread(()->{try {countDownLatch.await();System.out.println(Thread.currentThread().getName()+"\t卷王最后关灯走人");} catch (InterruptedException e) {e.printStackTrace();}}, "7").start();}
}

Semaphore信号量

import java.util.concurrent.Semaphore;
import java.util.concurrent.TimeUnit;/*** Semaphore案例：三辆小汽车抢车位* Semaphore信号量主要作用：1.用于多个共享资源的互斥使用，2.用于并发线程数的控制*/
public class Demo12Semaphore {public static void main(String[] args) {//模拟资源类，有3个空车位Semaphore semaphore = new Semaphore(3);for (int i = 1; i <= 6; i++) {new Thread(()->{try{//占有资源semaphore.acquire();System.out.println(Thread.currentThread().getName()+"\t抢到车位");try { TimeUnit.SECONDS.sleep(3); } catch (InterruptedException e) {e.printStackTrace(); }System.out.println(Thread.currentThread().getName()+"\t停车3秒后离开车位");} catch (Exception e) {e.printStackTrace();} finally {//释放资源semaphore.release();}}, "Thread-Car-"+String.valueOf(i)).start();}}
}

CyclicBarrier循环栅栏

import java.util.concurrent.CyclicBarrier;/*** 案例：集齐7龙珠召唤神龙*/
public class Demo13CyclicBarrier {public static void main(String[] args) {CyclicBarrier cyclicBarrier = new CyclicBarrier(7,()->{System.out.println("======召唤神龙");});for (int i = 1; i <= 14; i++) {final int tempInt = i;new Thread(()->{try {System.out.println(Thread.currentThread().getName() + "\t收集到第" + tempInt + "颗龙珠");cyclicBarrier.await();System.out.println(Thread.currentThread().getName() + "\t第" + tempInt + "颗龙珠飞走了");} catch (Exception e) {e.printStackTrace();}}, "Thread-"+String.valueOf(i)).start();}}
}

CyclicBarrier和CountDownLatch区别:

Condition接口(条件对象)

import java.util.Collections;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;/*** 案例：Tony仨小哥洗剪吹* 演示多线程之间按顺序调用，实现A->B->C* 三个线程Tony要求如下：*   tony雄雄-洗头，tony超超-理发，tony麦麦-吹干*   。。。*   tony雄雄-洗头，tony超超-理发，tony麦麦-吹干*  依次来10轮*/
public class Demo14ConditionDemo {public static void main(String[] args) {ShareData shareData = new ShareData();new Thread(()->{for (int i = 0; i < 10; i++) {shareData.wash();}}, "tony-雄雄").start();new Thread(()->{for (int i = 0; i < 10; i++) {shareData.cut();}}, "tony-超超").start();new Thread(()->{for (int i = 0; i < 10; i++) {shareData.cook();}}, "tony-麦麦").start();}
}
class ShareData {private volatile int number = 1; //tony-雄雄:1, tony-超超:2, tony-麦麦:3private Lock lock = new ReentrantLock();private Condition c1 = lock.newCondition(); //number == 1private Condition c2 = lock.newCondition(); //number == 2private Condition c3 = lock.newCondition(); //number == 3/*** A线程每一轮要执行的操作*/public void wash() {lock.lock();try{//判断while(number != 1){c1.await();//阻塞}//模拟线程执行的任务System.out.println(Thread.currentThread().getName()+"-洗头");//通知number = 2;c2.signal();//唤醒了超超} catch (Exception e) {e.printStackTrace();} finally {lock.unlock();}}/*** B线程每一轮要执行的操作*/public void cut() {lock.lock();try{//判断while(number != 2){c2.await();//阻塞}//模拟线程执行的任务System.out.println(Thread.currentThread().getName()+"-理发");//通知number = 3;c3.signal();//唤醒3} catch (Exception e) {e.printStackTrace();} finally {lock.unlock();}}public void cook() {lock.lock();try{//判断while(number != 3){c3.await();}//模拟线程执行的任务System.out.println(Thread.currentThread().getName()+"-吹干");//通知number = 1;c1.signal();//唤醒雄雄} catch (Exception e) {e.printStackTrace();} finally {lock.unlock();}}
}