Java Lock & Condition

/*
jdk1.5以后将同步和锁封装成了对象。 
并将操作锁的隐式方式定义到了该对象中，
将隐式动作变成了显示动作。

Lock接口： 出现替代了同步代码块或者同步函数。将同步的隐式锁操作变成现实锁操作。
同时更为灵活。可以一个锁上加上多组监视器。
lock():获取锁。
unlock():释放锁，通常需要定义finally代码块中。


Condition接口：出现替代了Object中的wait notify notifyAll方法。
            将这些监视器方法单独进行了封装，变成Condition监视器对象。
            可以任意锁进行组合。
await();
signal();
signalAll();

*/

import java.util.concurrent.locks.*;

class Resource
{
    private String name;
    private int count = 1;
    private boolean flag = false;

//    创建一个锁对象。
    Lock lock = new ReentrantLock();

    //通过已有的锁获取该锁上的监视器对象。
//    Condition con = lock.newCondition();

    //通过已有的锁获取两组监视器，一组监视生产者，一组监视消费者。
    Condition producer_con = lock.newCondition();
    Condition consumer_con = lock.newCondition();

    
    public  void set(String name)//  t0 t1
    {
        lock.lock();
        try
        {
            while(flag)
//            try{lock.wait();}catch(InterruptedException e){}//   t1    t0
            try{producer_con.await();}catch(InterruptedException e){}//   t1    t0
        
            this.name = name + count;//烤鸭1  烤鸭2  烤鸭3
            count++;//2 3 4
            System.out.println(Thread.currentThread().getName()+"...生产者5.0..."+this.name);//生产烤鸭1 生产烤鸭2 生产烤鸭3
            flag = true;
//            notifyAll();
//            con.signalAll();
            consumer_con.signal();
        }
        finally
        {
            lock.unlock();
        }
        
    }

    public  void out()// t2 t3
    {
        lock.lock();
        try
        {
            while(!flag)
//            try{this.wait();}catch(InterruptedException e){}    //t2  t3
            try{cousumer_con.await();}catch(InterruptedException e){}    //t2  t3
            System.out.println(Thread.currentThread().getName()+"...消费者.5.0......."+this.name);//消费烤鸭1
            flag = false;
//            notifyAll();
//            con.signalAll();
            producer_con.signal();
        }
        finally
        {
            lock.unlock();
        }
        
    }
}

class Producer implements Runnable
{
    private Resource r;
    Producer(Resource r)
    {
        this.r = r;
    }
    public void run()
    {
        while(true)
        {
            r.set("烤鸭");
        }
    }
}

class Consumer implements Runnable
{
    private Resource r;
    Consumer(Resource r)
    {
        this.r = r;
    }
    public void run()
    {
        while(true)
        {
            r.out();
        }
    }
}



class  ProducerConsumerDemo2
{
    public static void main(String[] args) 
    {
        Resource r = new Resource();
        Producer pro = new Producer(r);
        Consumer con = new Consumer(r);

        Thread t0 = new Thread(pro);
        Thread t1 = new Thread(pro);
        Thread t2 = new Thread(con);
        Thread t3 = new Thread(con);
        t0.start();
        t1.start();
        t2.start();
        t3.start();

    }
}

Example：

 

class BoundedBuffer {
   final Lock lock = new ReentrantLock();
   final Condition notFull  = lock.newCondition(); 
   final Condition notEmpty = lock.newCondition(); 

   final Object[] items = new Object[100];
   int putptr, takeptr, count;

   public void put(Object x) throws InterruptedException {
     lock.lock();
     try {
       while (count == items.length) 
         notFull.await();
       items[putptr] = x; 
       if (++putptr == items.length) putptr = 0;
       ++count;
       notEmpty.signal();
     } finally {
       lock.unlock();
     }
   }

   public Object take() throws InterruptedException {
     lock.lock();
     try {
       while (count == 0) 
         notEmpty.await();
       Object x = items[takeptr]; 
       if (++takeptr == items.length) takeptr = 0;
       --count;
       notFull.signal();
       return x;
     } finally {
       lock.unlock();
     }
   } 
 }