java线程间协作【wait(),notifyAll()】

柔情只为你懂 2022-08-11 16:36 131阅读 0赞

package com.zhiru;
    /*
     * 线程协作的一个例子【wait(),notifyAll()】
     * Cooker类负责做饭【做饭时不能吃饭】
     * Customer类负责吃饭【吃饭时不能做饭（好像不对。。。）】
     *对food的控制权在两个类之间来回传递
     */
    import java.util.concurrent.ExecutorService;
    import java.util.concurrent.Executors;
    import java.util.concurrent.TimeUnit;
    
    class Food {
    	//canEat是个很关键的布尔变量，它来标示当前的状态.
    	private boolean canEat = false;
    
    	//做饭完毕
    	public synchronized void cooked() {
    		canEat = true;// 可以吃了
    		notifyAll();// 唤醒程序去吃.
    	}
    
    	//吃饭完毕
    	public synchronized void eated() {
    		canEat = false;// 吃完了
    		notifyAll();// 唤醒程序去做饭.
    	}
    
    	//等待做饭
    	public synchronized void waitForCook() throws InterruptedException {
    		while (canEat == false)
    			// 不能吃，所以要等着把饭做好
    			wait();
    	}
    
    	//等待吃饭
    	public synchronized void waitForEat() throws InterruptedException {
    		while (canEat == true)
    			// 可以吃，所以等着吃完
    			wait();
    	}
    }
    //做饭类，做完饭后通知(通过调用cooked方法设置canEat变量为true)Customer类吃饭,同时自己调用wait方法挂起。
    class Cooker implements Runnable {
    
    	private Food fd;
    
    	public Cooker(Food fd) {
    		this.fd = fd;
    	}
    
    	@Override
    	public void run() {
    		// TODO Auto-generated method stub
    		try {
    			while (!Thread.interrupted()) {
    				System.out.println("开始做饭！。。。");
    				TimeUnit.MILLISECONDS.sleep(200);// 做饭花了200毫秒
    				fd.cooked();// 饭做好了
    				fd.waitForEat();// 饭等着被吃掉
    			}
    		} catch (InterruptedException e) {
    			prt("退出!因为被打断");
    		}
    		prt("做饭结束！！！");
    	}
    
    	public void prt(String s) {
    		System.out.print(s + "\n");
    	}
    
    }
    //吃饭类，吃完饭后通过调用eated方法改变canEat变量为false，来让Cooker类做饭，同时自己挂起。
    class Customer implements Runnable {
    
    	private Food fd;
    
    	public Customer(Food fd) {
    		this.fd = fd;
    	}
    
    	@Override
    	public void run() {
    		// TODO Auto-generated method stub
    		try {
    			while (!Thread.interrupted()) {
    				fd.waitForCook();// 等着饭做好
    				prt("开始吃饭!...");
    				TimeUnit.MILLISECONDS.sleep(200);// 用200毫秒将饭吃完.
    				fd.eated();// 饭吃完了.
    			}
    		} catch (InterruptedException e) {
    			prt("退出!因为被打断");
    		}
    		prt("吃饭结束！。。。");
    	}
    
    	public void prt(String s) {
    		System.out.print(s + "\n");
    	}
    
    }
    
    public class WaitAndNotify {
    
    	public static void main(String[] args) throws InterruptedException {
    		// TODO Auto-generated method stub
    		Food fd=new Food();
    		//ExecutorService类继承自Executors，
    		ExecutorService exec=Executors.newCachedThreadPool();//建立ExecutorService线程池
    		exec.execute(new Cooker(fd));//将Cooker实例放入线程池中
    		exec.execute(new Customer(fd));//将Customer实例放入线程池中
    		TimeUnit.SECONDS.sleep(5);//停5秒
    		exec.shutdownNow();//强行退出,他将调用任何它使用的线程的interrupt()方法，打断线程.
    	}
    
    }

参考数据：<<Thinking in Java>>4th edition