Java多线程之并发协作生产者消费者问题

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最简单的生产者消费者问题PV操作解法

int buffer；
    Semaphore sp=1,sc=0;
    //下面进程并发执行
    
    process producer(void)
    {
	while(1)
	{
				{生产一个产品product}；
				P(sp)；
				Buffer= product；
				V(sc);
	}
}
process consumer(void)
{
	while(1)
	{
				P(sc);
				{取走缓冲区的产品}
				V(sp);
				{消费该产品}
	}
}

同样原理，下面是Java多线程并发执行(synchronized给线程对象加锁)来实现

product产品类

public class product {
	private int n = 0;
	private boolean flag= false;
	private int i=1,j=1;
	
	public synchronized void produce() {
		System.out.println("剩余产品数:"+n);
		System.out.println(Thread.currentThread().getName()+"开始执行");
		if(flag) {
			//如果已有产品则让生产者线程等待
			try {
				wait();
			}catch(InterruptedException e) {e.printStackTrace();}
		}
		n++;  //如果无产品则生产产品
		System.out.println("已生产"+(i++)+"次");
		flag = true;
		notify();  //生产完后唤醒消费者线程
	}
	
	public synchronized void consume() {
		System.out.println("剩余产品数:"+n);
		System.out.println(Thread.currentThread().getName()+"开始执行");
		if(!flag) {
			//如果无产品则让消费者线程等待
			try {
				wait();
			}catch(InterruptedException e) {e.printStackTrace();}
		}
		n--;
		System.out.println("已消费"+(j++)+"次");
		flag = false;
		notify();
	}
	
	
}

生产者类

public class producer extends Thread{
	private product pro ;   //产品对象
	public producer(product pro) {
		this.pro = pro;
	}
	public  void run() {
		while(true) {
			try {
				Thread.sleep(3000);    //wait释放对象锁，sleep不会释放对象锁
			}catch(InterruptedException e){e.printStackTrace();}
			
			pro.produce(); //生产产品
			
		}

	}
}

消费者类

public class consumer extends Thread{
	private product pro ;   //产品对象
	public consumer(product pro) {
		this.pro = pro;
	}
	public  void run() {
		while(true) {
			try {
				Thread.sleep(3000);    //wait释放对象锁，sleep不会释放对象锁
			}catch(InterruptedException e){e.printStackTrace();}
			
			pro.consume(); //消费产品
			
		}

	}
}

最后是main类

public class producer_consumer {
	public static void main(String[] args) {
		product pro = new product();
		producer pThread = new producer(pro);
		consumer cThread = new consumer(pro);
		//pThread.start();
		//cThread.start();
		Thread t1 = new Thread(pThread,"生产者线程");
		Thread t2 = new Thread(cThread,"消费者线程");
		t1.start();
		t2.start();
		
	}
}

程序结果图