java 中多线程生产者消费者问题详细介绍

java 中多线程生产者消费者问题

前言：

一般面试喜欢问些线程的问题，较基础的问题无非就是死锁，生产者消费者问题，线程同步等等，在前面的文章有写过死锁，这里就说下多生产多消费的问题了

import java.util.concurrent.locks.*;class BoundedBuffer {  final Lock lock = new ReentrantLock();//对象锁  final Condition notFull = lock.newCondition(); //生产者监视器  final Condition notEmpty = lock.newCondition(); //消费者监视器  //资源对象  final Object[] items = new Object[10];  //putptr生产者角标，takeptr消费者角标，count计数器(容器的实际长度)  int putptr, takeptr, count;  public void put(Object x) throws InterruptedException {    //生产者拿到锁   lock.lock();   try {     //当实际长度不满足容器的长度    while (count == items.length)       //生产者等待     notFull.await();    //把生产者产生对象加入容器    items[putptr] = x;     System.out.println(Thread.currentThread().getName()+"   put-----------"+count);    Thread.sleep(1000);    //如果容器的实际长==容器的长，生产者角标置为0    if (++putptr == items.length) putptr = 0;    ++count;    //唤醒消费者    notEmpty.signal();   } finally {     //释放锁    lock.unlock();   }  }  public Object take() throws InterruptedException {   lock.lock();   try {    while (count == 0)       //消费者等待     notEmpty.await();    Object x = items[takeptr];     System.out.println(Thread.currentThread().getName()+"   get-----------"+count);    Thread.sleep(1000);    if (++takeptr == items.length) takeptr = 0;    --count;    //唤醒生产者    notFull.signal();    return x;   } finally {     //释放锁    lock.unlock();   }  }  }class Consu implements Runnable{  BoundedBuffer bbuf;  public Consu(BoundedBuffer bbuf) {    super();    this.bbuf = bbuf;  }  @Override  public void run() {    while(true){    try {      bbuf.take() ;    } catch (InterruptedException e) {      // TODO Auto-generated catch block      e.printStackTrace();    }    }  }}class Produ implements Runnable{  BoundedBuffer bbuf;  int i=0;  public Produ(BoundedBuffer bbuf) {    super();    this.bbuf = bbuf;  }  @Override  public void run() {    while(true){      try {        bbuf.put(new String(""+i++)) ;      } catch (InterruptedException e) {        // TODO Auto-generated catch block        e.printStackTrace();      }    }  }}//主方法class Lock1{  public static void main(String[] args) {    BoundedBuffer bbuf=new BoundedBuffer();    Consu c=new Consu(bbuf);    Produ p=new Produ(bbuf);    Thread t1=new Thread(p);    Thread t2=new Thread(c);    t1.start();    t2.start();    Thread t3=new Thread(p);    Thread t4=new Thread(c);    t3.start();    t4.start();  }}