communicationdemo.java

java入门经典教程 java入门经典教程 java入门经典教程

// 例4.6.1 CommunicationDemo.java 描述：生产者－－消费者之间的消息传递过程
class ShareData
{
	private char c;  
	private boolean isProduced = false; // 信号量
	public synchronized void putShareChar(char c)  // 同步方法putShareChar()
{ 
		if (isProduced)     // 如果产品还未消费，则生产者等待
{  
			try
{
				wait();        // 生产者等待
			}catch(InterruptedException e){
	e.printStackTrace();
}
		}
		this.c = c;  
		isProduced = true;   // 标记已经生产
		notify();             // 通知消费者已经生产，可以消费
	}
	public synchronized char getShareChar()  // 同步方法getShareChar()
{
		if (!isProduced)    // 如果产品还未生产，则消费者等待
{   
			try
{
				wait();       // 消费者等待
			}catch(InterruptedException e){
				e.printStackTrace();
}  
		} 
		isProduced = false; // 标记已经消费
		notify();            // 通知需要生产
		return this.c;
	}
}
class Producer extends Thread     // 生产者线程
{  
	private ShareData s;
	Producer(ShareData s)
{
		this.s = s;
	}
	public void run()
{
		for (char ch = 'A'; ch <= 'D'; ch++)
{
			try 
{
				Thread.sleep((int)(Math.random()*3000));
			}catch(InterruptedException e){
				e.printStackTrace();
}
			s.putShareChar(ch);  // 将产品放入仓库
			System.out.println(ch + " is produced by Producer.");
		}
	}
}
class Consumer extends Thread    // 消费者线程
{ 
	private ShareData s;
	Consumer(ShareData s)
{
		this.s = s;
	}
	public void run()
{
		char ch;
		do{
			try
{
				Thread.sleep((int)(Math.random()*3000));
			}catch(InterruptedException e){
				e.printStackTrace();
}
			ch = s.getShareChar();    // 从仓库中取出产品
			System.out.println(ch + " is consumed by Consumer. ");
		}while (ch != 'D');
	}
}
class CommunicationDemo
{
	public static void main(String[] args)
{
		ShareData s = new ShareData();
		new Consumer(s).start();
		new Producer(s).start();
	}
}