线程通信——经典的生产者—消费者问题

线程通信，经典的生产者消费者问题：
在一个商店里，售货员负责销售某件产品，生产者将产品交给售货员，而消费者取走产品，假设商店里产品数量不能超过20个，如果生产更多产品售货员会让生产者停下，等数量少于20时继续生产；如果没有产品了售货员会告诉消费者等待，等产品来了再通知消费者取走产品。
上代码：

package java1;
class Clerk{
	private  int number=0;

	public synchronized void consumeProduct() {
		if(number>0) {
			System.out.println(Thread.currentThread().getName()+"开始消费第"+number+"个产品");
			number--;
			notify();
		}else {
			try {
				wait();
			} catch (InterruptedException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
		// TODO Auto-generated method stub
		
	}

	public synchronized void produceProduct() {
		if(number<20) {
			number++;
			System.out.println(Thread.currentThread().getName()+":开始生产第"+number+"个产品");
			notify();
		}else {
			try {
				wait();
			} catch (InterruptedException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
		// TODO Auto-generated method stub
		
	}
	
}
class Productor implements Runnable{
	private Clerk clerk;
	

	public Productor(Clerk clerk) {
		super();
		this.clerk = clerk;
	}


	@Override
	public void run() {
		System.out.println(Thread.currentThread().getName()+":生产者开始生产产品！");
		while(true) {
			try {
				Thread.sleep(10);
			} catch (InterruptedException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
			clerk.produceProduct();
		}
		// TODO Auto-generated method stub
		
	}
	
}
class Customer implements Runnable{
	private Clerk clerk;
	

	public Customer(Clerk clerk) {
		super();
		this.clerk = clerk;
	}


	@Override
	public void run() {
		System.out.println(Thread.currentThread().getName()+":消费者开始消费产品！");
		while(true) {
			try {
				Thread.sleep(30);
			} catch (InterruptedException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
			clerk.consumeProduct();
		}
		// TODO Auto-generated method stub
		
	}
	
}
public class ProductTest {
	public static void main(String[] args) {
		Clerk clerk=new Clerk();
		Productor p=new Productor(clerk);
		Customer c=new Customer(clerk);
		Thread t1=new Thread(p,"生产者");
		Thread t2=new Thread(c,"消费者");
		t1.start();
		t2.start();
	}

}