Java——线程通信

布满荆棘的人生 2022-07-13 02:29 156阅读 0赞

# Java——线程通信 #

线程通信中的三个方法：

>  *  wait() 将当前进程挂起，释放CPU，进入等待队列
>  *  notify() 将线程等待队列中优先级最高的线程唤醒
>  *  notifyAll() 将等待队列中的所有线程唤醒

注°只能在同步代码块或者同步方法中使用

1、使用线程通信使得两个账户交替存钱

package com.kexin.study2;
    
    public class TestCommunication {
    
    	public static void main(String[] args) {
    		Account acc = new Account();
    		User user1 = new User(acc);
    		User user2 = new User(acc);
    		
    		user1.setName("甲");
    		user2.setName("乙");
    	
    		user1.start();
    		user2.start();
    	}
    
    }
    class Account{
    	private double money;
    	public synchronized void setMoney(double money){
    		//将线程唤醒
    		notify();
    		this.money += money;
    		System.out.println(Thread.currentThread().getName()+"---->"+this.money);
    		try {
    			//将线程挂起
    			wait();
    		} catch (InterruptedException e) {
    			// TODO Auto-generated catch block
    			e.printStackTrace();
    		}
    	}
    }
    class User extends Thread{
    	private Account acc;
    	public User(Account acc){
    		this.acc = acc;
    	}
    	@Override
    	public void run() {
    		for(int i =0 ;i<3;i++)
    			acc.setMoney(1000);
    	}
    	
    }

2、生产者/消费者问题

生产者/消费者问题是讲解线程必提的一个例子，意思是生产者和消费者两个线程共享一个buffer，生产者往里生产东西，消费者从里面取东西，而两者不可同时访问这个buffer

package com.kexin.study2;
    
    public class TestProductConsume {
    
    	public static void main(String[] args) {
    		ProductBuffer pb = new ProductBuffer();
    		Product p = new Product(pb);
    		Product p1 = new Product(pb);
    		Consume c = new Consume(pb);
    		
    		p.setName("生产者");
    		p1.setName("生产者1");
    		c.setName("消费者");
    		
    		p.start();
    		p1.start();
    		c.start();
    	}
    
    }
    //产品BUffer
    class ProductBuffer{
    	int product_nums = 0;	//现有的产品数
    	private final int max_buffer = 5;	//设置缓冲池大小
    	//生产产品
    	public synchronized void setProduct(){
    		if(product_nums>=max_buffer){
    			try {
    				wait();
    			} catch (InterruptedException e) {
    				// TODO Auto-generated catch block
    				e.printStackTrace();
    			}
    		}else{
    			product_nums++;
    			System.out.println(Thread.currentThread().getName()+"生产了第"+product_nums+"个产品");
    			notifyAll();
    		}
    	}
    	//消费产品
    	public synchronized void getProduct(){
    		if(product_nums<=0){
    			try {
    				wait();
    			} catch (InterruptedException e) {
    				// TODO Auto-generated catch block
    				e.printStackTrace();
    			}
    		}else{
    			product_nums--;
    			System.out.println(Thread.currentThread().getName()+"消费了第"+product_nums+"个产品");
    			notifyAll();
    		}
    	}
    }
    //生产者线程
    class Product extends Thread{
    	ProductBuffer buffer;
    	public Product(ProductBuffer buffer){
    		this.buffer = buffer;
    	}
    	@Override
    	public void run() {
    		//生产者生产产品
    		System.out.println("生产者生产产品...");
    		while(true){
    			buffer.setProduct();
    		}
    	}
    	
    }
    //消费者线程
    class Consume extends Thread{
    	ProductBuffer buffer;
    	public Consume(ProductBuffer buffer){
    		this.buffer = buffer;
    	}
    	@Override
    	public void run() {
    		//消费者消费产品
    		try {
    			Thread.currentThread().sleep(1000);
    		} catch (InterruptedException e) {
    			// TODO Auto-generated catch block
    			e.printStackTrace();
    		}
    		System.out.println("消费者消费产品...");
    		while(true){
    			buffer.getProduct();
    		}
    	}
    }

线程over了 ![大笑][laugh.gif]

[laugh.gif]: /images/20220713/49ffeb4640ef4a439da3f7d955bd44e4.png