描述：共享变量池大小为5，生产者从池中放入一个物品，消费者从池中拿去一个物品。

一：定义共享资源：

public class PublicResources {
    private int count = 0;  // max = 5
    
    public void reduce() {   //消费者消费
    	synchronized(this) {
    		
    		while(count <= 0) {  //考虑为什么不用if而用while
    			try {
    				System.out.println("等待生产");
					wait();
				} catch (InterruptedException e) {
					e.printStackTrace();
				}
    		}
    		
    		System.out.println("consumer is reducing " + count);
    		count--;
    		notify();    //唤醒正在等待的生成者
    	}
    	
    }
    
    public void add() {
    	synchronized(this) {
    		
    		while(count >= 5) {
    			try {
    				System.out.println("等待消费");
					wait();
				} catch (InterruptedException e) {
					e.printStackTrace();
				}
    		}
    		
    		count++;
    		System.out.println("producer is add " + count);
    		notify();  //唤醒正在等待的消费者
    	}
    }
}

2、生产者模型：

/**生产者*/
public class Producer implements Runnable{
	private PublicResources pr;

	public Producer() {
		// TODO Auto-generated constructor stub
	}
	
	public Producer(PublicResources pr) {
		this.pr = pr;
	}
	
	@Override
	public void run() {
		for(int i = 0; i < 10; i++) {
			try {
				pr.add();
				Thread.sleep(1000*(long)Math.random());
			} catch (InterruptedException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
		
	}

}

/**消费者*/
public class Consumer implements Runnable{
	private PublicResources pr;
    
	public Consumer() {
		// TODO Auto-generated constructor stub
	}
	
	public Consumer(PublicResources pr) {
		this.pr = pr;
	}
	
	@Override
	public void run() {
		for(int i = 0; i < 10; i++) {
			try {
				pr.reduce();
				Thread.sleep(1000*(long)Math.random());
			} catch (InterruptedException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
	}

}

public class Test_Producer_Consumer {

	public static void main(String[] args) {
		PublicResources ps = new PublicResources();
		
		Thread thread1 = new Thread(new Producer(ps));
		Thread thread2 = new Thread(new Consumer(ps));
		Thread thread3 = new Thread(new Producer(ps));
		Thread thread4 = new Thread(new Consumer(ps));
		thread1.start();
		thread2.start();
		thread3.start();
		thread4.start();
		

	}

}