生产者消费者模型

今天药忘吃喽~ 2024-02-18 21:19 56阅读 0赞

描述：共享变量池大小为5，生产者从池中放入一个物品，消费者从池中拿去一个物品。

一：定义共享资源：

public class PublicResources {
        private int count = 0;  // max = 5
        
        public void reduce() {   //消费者消费
        	synchronized(this) {
        		
        		while(count <= 0) {  //考虑为什么不用if而用while
                   // 试想当一个线程从wait状态被唤醒时，仍然可能出现没有资源的情况，所以这里需要用while来处理
        			try {
        				System.out.println("等待生产");
    					wait();
    				} catch (InterruptedException e) {
    					e.printStackTrace();
    				}
        		}
        		
        		System.out.println("consumer is reducing " + count);
        		count--;
        		notify();    //唤醒正在等待的生成者
        	}
        	
        }
        
        public void add() {
        	synchronized(this) {
        		
        		while(count >= 5) {
        			try {
        				System.out.println("等待消费");
    					wait();
    				} catch (InterruptedException e) {
    					e.printStackTrace();
    				}
        		}
        		
        		count++;
        		System.out.println("producer is add " + count);
        		notify();  //唤醒正在等待的消费者
        	}
        }
    }

2、生产者模型：

/**生产者*/
    public class Producer implements Runnable{
    	private PublicResources pr;
    
    	public Producer() {
    		// TODO Auto-generated constructor stub
    	}
    	
    	public Producer(PublicResources pr) {
    		this.pr = pr;
    	}
    	
    	@Override
    	public void run() {
    		for(int i = 0; i < 10; i++) {
    			try {
    				pr.add();
    				Thread.sleep(1000*(long)Math.random());
    			} catch (InterruptedException e) {
    				// TODO Auto-generated catch block
    				e.printStackTrace();
    			}
    		}
    		
    	}
    
    }

3、消费者模型：

/**消费者*/
    public class Consumer implements Runnable{
    	private PublicResources pr;
        
    	public Consumer() {
    		// TODO Auto-generated constructor stub
    	}
    	
    	public Consumer(PublicResources pr) {
    		this.pr = pr;
    	}
    	
    	@Override
    	public void run() {
    		for(int i = 0; i < 10; i++) {
    			try {
    				pr.reduce();
    				Thread.sleep(1000*(long)Math.random());
    			} catch (InterruptedException e) {
    				// TODO Auto-generated catch block
    				e.printStackTrace();
    			}
    		}
    	}
    
    }

4、测试类：

public class Test_Producer_Consumer {
    
    	public static void main(String[] args) {
    		PublicResources ps = new PublicResources();
    		
    		Thread thread1 = new Thread(new Producer(ps));
    		Thread thread2 = new Thread(new Consumer(ps));
    		Thread thread3 = new Thread(new Producer(ps));
    		Thread thread4 = new Thread(new Consumer(ps));
    		thread1.start();
    		thread2.start();
    		thread3.start();
    		thread4.start();
    		
    
    	}
    
    }