1 wait()和notify实现生产消费者模型
package com.qunar.conditionTest; import java.util.PriorityQueue; /** * Created by chen on 2018/4/22. */ public class Testwaitnotify { private int queueSize = 10; private PriorityQueue<Integer> queue = new PriorityQueue<>(queueSize); public static void main(String[] args) { Testwaitnotify test = new Testwaitnotify(); Producer producer = test.new Producer(); Consumer consumer = test.new Consumer(); producer.start(); consumer.start(); } class Consumer extends Thread { public void run(){ consume(); } private void consume(){ while (true) { synchronized (queue) { //进入同步代码块 while (queue.size() == 0) {//这里一定要使用while不能使用if,因为当生产者生产一个商品时,会调用notifyAll唤醒所有consumer等待线程,while保证只有一个线程能过通过,其他consumer 线程在while条件中再次被wait try { queue.wait(); //让当前线程等待,必须在同步代码块中执行 } catch (InterruptedException e) { e.printStackTrace(); queue.notify(); //异常是唤醒当前等待线程 } } queue.poll(); queue.notify(); //释放当前线程持有的对象锁 System.out.println("从队列中取走一个元素,队列剩余"+queue.size()+"个元素"); } } } } class Producer extends Thread { public void run(){ prooduce(); } private void prooduce() { while (true){ synchronized(queue){ while (queue.size() == queueSize){ //这里也一样,必须使用while做判断语句,保证每次允许一个线程通过,其他线程在while循环中再次被wait try { queue.wait(); } catch (InterruptedException e) { e.printStackTrace(); queue.notify(); } } queue.add(1); queue.notify(); System.out.println("向队列取中插入一个元素,队列剩余空间:"+(queueSize-queue.size())); } } } } }
2 使用ReetrantLock方式实现生产消费模型
package com.qunar.conditionTest; import java.util.PriorityQueue; import java.util.concurrent.locks.Condition; import java.util.concurrent.locks.Lock; import java.util.concurrent.locks.ReentrantLock; /** * Created by jw.chen on 2018/4/22. */ public class TestReentrantLock { private int queueSize = 1; private PriorityQueue<Integer> queue = new PriorityQueue<>(queueSize); private Lock lock = new ReentrantLock(); //定义ReetrantLock锁 private Condition produceLock = lock.newCondition(); //produce条件锁 private Condition consumeLock = lock.newCondition(); //consume条件锁 public static void main(String[] args) { TestReentrantLock test = new TestReentrantLock(); Producer producer = test.new Producer(); Consumer consumer = test.new Consumer(); producer.start(); consumer.start(); } class Consumer extends Thread { public void run(){ consume(); } private void consume(){ while (true) { lock.lock(); //condition条件锁必须在同步代码块中执行 try { while (queue.size() == 0) { System.out.println("队列空,等待数据"); try { consumeLock.await(); //队列为空时,让consume锁等待,注意这里使用的是await()不是wait()方法, } catch (InterruptedException e) { e.printStackTrace(); } } queue.poll(); produceLock.signal(); //消费后释放produce lock,使其继续生产工作 System.out.println("从队列取走一个元素,队列剩余" + queue.size() + "个元素"); }finally { lock.unlock(); //finally中释放锁 } } } } class Producer extends Thread { public void run(){ prooduce(); } private void prooduce() { while (true){ lock.lock(); try { while (queue.size() == queueSize) { try { produceLock.await(); } catch (InterruptedException e) { e.printStackTrace(); } } queue.offer(1); System.out.println("向队列取中插入一个元素,队列剩余空间:"+(queueSize-queue.size())); consumeLock.signal(); } finally { lock.unlock(); } } } } }
需要注意的点
使用条件锁,需要在Lock环境下使用,condition锁使用的wait方法是await方法,这里需要注意
使用condition.signal()唤醒对应条件的应用