java实现PV操作解决生产者-消费者问题

March 27, 2019

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948 words

### 代码
    package 生产者_消费者问题;
    
    import java.util.Random;
    
    public class Semaphore {
    	int value;
        Semaphore(int value)
        {
            this.value = value;
        }
     
    }
    class Buffer {
    	static int n=5;//缓冲区大小
    	int[] buffer=new int[n];
        Semaphore empty = new Semaphore(n);
        Semaphore full = new Semaphore(0);
        Semaphore mutex = new Semaphore(1);
        int data_p=1;
        int data_c=0;
        
        //信号量减一，若信号量小于0，本线程阻塞。
        synchronized void P(Semaphore S) 
            {
                S.value--;
                if(S.value < 0){
                    try {
                        this.wait();
                    } catch (InterruptedException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }
                }
            }
        //信号量加一，若信号量依旧<=0,便将阻塞队列里一线程唤醒
        synchronized void V(Semaphore S)
            {
                S.value++;
                if(S.value <= 0){
                    this.notify();
                }
    
            }
        void producer(int i) {
        	
        		P(empty);
        		if(buffer[i]==0) {
        			P(mutex);
                	buffer[i]=data_p;
                	
                	System.out.println("生产了"+i);
                	V(mutex);
        		}
            	V(full);
        	
        }
        void consumer(int j) {
        	
        		P(full);
        		if(buffer[j]==1) {
        			P(mutex);
        			buffer[j]=data_c;
        			
        			System.out.println("消费了"+j);
            		V(mutex);
        		}
            	V(empty);
        	
        }
    }
    
    //生产者发出5个请求，每次间隔时间100ms
    class Produce implements Runnable
    {
      Buffer buffer = null;
      Produce(Buffer buffer)
      {
          this.buffer = buffer;
      }
      public void run() {
          for(int i=0; i<5; i++)
          {
        	  Random rand = new Random();
              buffer.producer(rand.nextInt(5));
              try {
                  Thread.sleep(100);
              } catch (InterruptedException e) {
                  // TODO Auto-generated catch block
                  e.printStackTrace();
              }
          }
    
      }
    
    }
    
    //消费者发出5个请求，每次间隔时间为500ms
    class Consumer implements Runnable
    {
    
      Buffer buffer = null;
      Consumer(Buffer buffer)
      {
          this.buffer = buffer;
      }
    
      
      public void run() {
          for(int i=0; i<5; i++)
          {
        	  Random rand = new Random();
              buffer.consumer(rand.nextInt(5));
              try {
                  Thread.sleep(500);
              } catch (InterruptedException e) {
                  // TODO Auto-generated catch block
                  e.printStackTrace();
              }
          }
    
      }
    
    }

package 生产者_消费者问题;
    
    public class main {
    
    	public static void main(String[] args) {
    
    		Buffer buff = new Buffer();
            Consumer consumer = new Consumer(buff);
            Produce prod = new Produce(buff);
            new Thread(prod).start();
            new Thread(consumer).start();
    	}
    
    }
    
### 输出结果
![](https://i.loli.net/2019/03/27/5c9b7561cefa8.png) ![](https://i.loli.net/2019/03/27/5c9b7561e3c3e.png) ![](https://i.loli.net/2019/03/27/5c9b7561e3ebd.png) ![](https://i.loli.net/2019/03/27/5c9b7561e3eb8.png) ![](https://i.loli.net/2019/03/27/5c9b756205578.png)

Last modification：March 27th, 2019 at 09:09 pm

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java实现PV操作解决生产者-消费者问题