Java- 线程间通信-多生产者多消费者问题解决

生产者,消费者。
多生产者,多消费者的问题。
if判断标记,只有一次,会导致不该运行的线程运行了。出现了数据错误的情况。

while判断标记,解决了线程获取执行权后,是否要运行!
notify:只能唤醒一个线程,如果本方唤醒了本方,没有意义。而且while判断标记+notify会导致死锁。
notifyAll解决了本方线程一定会唤醒对方线程的问题。

class Resource
{
    private String name;
    private int count = 1;
    private boolean flag = false;
    public synchronized void set(String name)//  
    {
        while(flag)
            try{this.wait();}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..."+this.name);//生产烤鸭1 生产烤鸭2 生产烤鸭3
        flag = true;
        notifyAll();
    }

    public synchronized void out()//  t3
    {
        while(!flag)
            try{this.wait();}catch(InterruptedException e){}    //t2  t3
        System.out.println(Thread.currentThread().getName()+"...消费者........"+this.name);//消费烤鸭1
        flag = false;
        notifyAll();
    }
}

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  ProducerConsumerDemo
{
    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();

    }
}

标签: 多线程