JAVA多线程（五）用lock、synchronized、阻塞队列三种方法实现生产者消费者模式

这篇博客算是上一篇JAVA多线程（三）生产者消费者模式及实现方法的补充。用三种方法（lock、synchronized、阻塞队列）实现生产者消费者模式。具体内容是：生产者产生随机数（为了方便阅读结果，我把随机数限定在10以内的整数），消费者读取并打印。

1 阻塞队列实现生产者消费者模式

阻塞队列是最简单的实现方法

import java.util.concurrent.BlockingQueue;import java.util.concurrent.LinkedBlockingQueue;import java.util.logging.Level;import java.util.logging.Logger;import java.util.Random;public class BlockingQueuePattern {    public static void main(String args[]){     //阻塞队列     BlockingQueue sharedQueue = new LinkedBlockingQueue();     //创建生产者线程和消费者线程     Thread prodThread = new Thread(new Producer(sharedQueue));     Thread consThread = new Thread(new Consumer(sharedQueue));     //启动生产者线程和消费者线程     prodThread.start();     consThread.start();    }}//生产者类class Producer implements Runnable {    private final BlockingQueue sharedQueue;    public Producer(BlockingQueue sharedQueue) {        this.sharedQueue = sharedQueue;    }    @Override    public void run() {        for(int i=0; i<10; i++){            try {                //产生10以内的随机整数放入阻塞队列                Random random = new Random();                int ProdRandom=random.nextInt(10);                System.out.println("Produced: " + ProdRandom);                sharedQueue.put(ProdRandom);            } catch (InterruptedException ex) {                Logger.getLogger(Producer.class.getName()).log(Level.SEVERE, null, ex);            }        }    }}//消费者类class Consumer implements Runnable{    private final BlockingQueue sharedQueue;    public Consumer (BlockingQueue sharedQueue) {        this.sharedQueue = sharedQueue;    }    @Override    public void run() {        while(true){            try {                System.out.println("Consumed: "+ sharedQueue.take());            } catch (InterruptedException ex) {                Logger.getLogger(Consumer.class.getName()).log(Level.SEVERE, null, ex);            }        }    }} Output：Produced: 4Produced: 7Produced: 8Consumed: 4Consumed: 7Produced: 6Consumed: 8Consumed: 6Produced: 1Produced: 7Consumed: 1Consumed: 7Produced: 3Produced: 5Consumed: 3Consumed: 5Produced: 9Produced: 7Consumed: 9Consumed: 7

2 lock实现生产者消费者模式

既然不用JAVA提供给我们的现成的阻塞队列，我们不如自己创建一个队列，代码如下:

import java.util.LinkedList;import java.util.Random;import java.util.concurrent.locks.Condition;import java.util.concurrent.locks.Lock;import java.util.concurrent.locks.ReentrantLock;public class OptimisticLockPattern {    public static void main(String[] args){              SelfQueue selfqueue = new SelfQueue();         //创建生产者线程和消费者线程         Thread prodThread = new Thread(new Producer(selfqueue));         Thread consThread = new Thread(new Consumer(selfqueue));         //启动生产者线程和消费者线程         prodThread.start();         consThread.start();    }}class SelfQueue{    int max = 5;    LinkedList<Integer> ProdLine = new LinkedList<Integer>();    Lock lock = new ReentrantLock();     Condition full = lock.newCondition();      Condition empty = lock.newCondition();    public void produce(int ProdRandom){               try {            lock.lock();            while(max == ProdLine.size()){                System.out.println("存储量达到上限，请等待");                full.await();            }            ProdLine.add(ProdRandom);            empty.signal();        } catch (InterruptedException e) {            e.printStackTrace();        }finally{            lock.unlock();        }    }     public int consume(){          int m = 0;        try {            lock.lock();            while(ProdLine.size() == 0){                System.out.println("队列是空的，请稍候");                empty.await();            }            m = ProdLine.removeFirst();            full.signal();         } catch (InterruptedException e) {            e.printStackTrace();        }finally{            lock.unlock();            return m;        }    }}//生产者class Producer implements Runnable{    private final SelfQueue selfqueue;    public Producer(SelfQueue selfqueue) {          this.selfqueue = selfqueue;    }    public void run() {      for (int i = 0; i < 10; i++) {            Random random = new Random();            int ProdRandom=random.nextInt(10);            System.out.println("Produced: " + ProdRandom);            selfqueue.produce(ProdRandom);                }  }}//消费者class Consumer implements Runnable{    private final SelfQueue selfqueue;    public Consumer(SelfQueue selfqueue) {          this.selfqueue = selfqueue;    }    public void run() {      while(true) {              System.out.println("Consumed: "+ selfqueue.consume());      }  }}Output:Produced: 1Produced: 9Consumed: 1Consumed: 9队列是空的，请稍候Produced: 9Produced: 1Consumed: 9Produced: 8Consumed: 1Consumed: 8队列是空的，请稍候Produced: 6Produced: 8Consumed: 6Produced: 4Consumed: 8Produced: 4Consumed: 4Produced: 0Consumed: 4Consumed: 0队列是空的，请稍候

3 synchronized实现生产者消费者模式

synchronized不需要自己手动解锁，这里用到了前面提过的wait()&notify()方法。

import java.util.Random;public class PessimisticLockPattern {    public static void main(String[] args){              SelfQueue selfqueue = new SelfQueue();         //创建生产者线程和消费者线程         Thread prodThread = new Thread(new Producer(selfqueue));         Thread consThread = new Thread(new Consumer(selfqueue));         //启动生产者线程和消费者线程         prodThread.start();         consThread.start();    }}class SelfQueue{    int index = 0;     int[] ProdLine = new int[6];    public synchronized void produce(int ProdRandom){        while(index == ProdLine.length){            try {                this.wait();            } catch (InterruptedException e) {                e.printStackTrace();            }        }        this.notify();        ProdLine[index] = ProdRandom;        index++;    }    public synchronized int consume(){        while(index == 0){            try {                this.wait();            } catch (InterruptedException e) {                e.printStackTrace();            }        }        this.notify();        index--;        return ProdLine[index];    }}//生产者class Producer implements Runnable{    private final SelfQueue selfqueue;    public Producer(SelfQueue selfqueue) {        this.selfqueue = selfqueue;  }  public void run() {    for (int i = 0; i < 10; i++) {            Random random = new Random();            int ProdRandom = random.nextInt(10);        System.out.println("Produced: " + ProdRandom);            selfqueue.produce(ProdRandom);              }}}//消费者class Consumer implements Runnable{    private final SelfQueue selfqueue;  public Consumer(SelfQueue selfqueue) {        this.selfqueue = selfqueue;  }  public void run() {    while(true) {          System.out.println("Consumed: "+ selfqueue.consume());    }}}Output:Produced: 3Produced: 3Consumed: 3Produced: 8Produced: 3Consumed: 3Produced: 2Produced: 6Consumed: 3Produced: 7Produced: 8Produced: 1Produced: 9Consumed: 6Consumed: 9Consumed: 1Consumed: 8Consumed: 7Consumed: 2Consumed: 8