java 厨师,顾客,订餐的多线程示例程序_利用多线程技术编写java程序,模拟顾客、经理及厨师在餐馆中的业务流程-优快云博客

这是一个展示Java多线程概念的实例，包括厨师、顾客和订餐过程。重点在于wait方法需在循环中使用，避免死锁采用notifyAll，以及通过sleep方法控制执行速度。同时，程序包含异常处理机制，确保线程安全。

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厨师,顾客,订餐的多线程示例程序

1)wait方法要在一个循环中

public void waitForChef() throws InterruptedException {
 		while (readyFlag)
 			wait();
 	}

2)由于厨师线程有多个,顾客有多个,所以要用notifyAll方法,而不是notify,因为notify很容易就产生死锁

3)TimeUnit.MILLISECONDS.sleep(200); 用于降低程序的运行速度,用于示例

	while (!Thread.interrupted()) { <span style="font-family: Arial, Helvetica, sans-serif;">}</span>

用于检测异常,异常可能发生在sleep()方法中,也可能发生在wait方法中,也可能在while体中的其他部分,这时候下次执行while便会退出while循环,

由于

Thread.interrupted()

方法会清楚异常标识,所以最后

exec.shutdownNow();

执行时,有一部分线程的catch语句中的print语句并不会得到执行

5)条件检测和线程的主要任务执行都要放在synchronized块中

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

class Meal {
	private static int  count=0;
    private final int orderNum=++count	;
    public String toString() {
        return " Meal "+orderNum;
    }
    
}
class WaitPerson implements Runnable {
    private Restaurant restaurant;

    public WaitPerson( Restaurant restaurant) {
        this.restaurant=restaurant;
    }

    public void run() {
        try {
        	while (!Thread.interrupted()) {
                synchronized(restaurant) {
                	restaurant.waitForEating();
                    System.out.println("The WaitPerson "+Thread.currentThread().getId()+" has eaten " + restaurant.meal);
                    restaurant.setReadyFlag(false);
                    restaurant.notifyAll();
                }
        	}
        } catch(InterruptedException e) {
        	System.out.print("Exiting via interrupt in WaitPerson in thread-->"
					+ Thread.currentThread().getId());
        }
        System.out.print("Exiting in WaitPerson in thread-->"
				+ Thread.currentThread().getId());
    }

}
class Chef implements Runnable {

    private Restaurant restaurant;
    public Chef( Restaurant restaurant) {
        this.restaurant=restaurant;
    }

    public void run() {
        try {
        	while (!Thread.interrupted()) {
                synchronized(restaurant) {
                 TimeUnit.MILLISECONDS.sleep(200);
                	restaurant.waitForChef();
                	restaurant.meal=new Meal();
                    System.out.println("The Chef "+Thread.currentThread().getId()+" has made" + restaurant.meal);
                    restaurant.setReadyFlag(true);
                    restaurant.notifyAll();
                }
            }
        } catch(InterruptedException e) {
        	System.out.print("Exiting via interrupt in Chef in thread-->"
					+ Thread.currentThread().getId());
        }
        System.out.print("Exiting in Chef in thread-->"
				+ Thread.currentThread().getId());
    }

}

public class Restaurant {
     private boolean readyFlag=false; //true 做好了, false代表没做好
     
     public Meal meal=null;
     
     public void setReadyFlag(boolean readyFlag) {
		this.readyFlag = readyFlag;
	}

	public void waitForChef() throws InterruptedException {
 		while (readyFlag)
 			wait();
 	}

 	public void waitForEating() throws InterruptedException {
 		while (readyFlag == false)
 			wait();
 	}
     

    public static void main(String[] args) throws Exception {
        Restaurant restaurant=new Restaurant();

    	ExecutorService exec = Executors.newFixedThreadPool(20);
		for (int i = 0; i < 10; i++) {
			exec.execute(new Chef(restaurant));
			exec.execute(new WaitPerson(restaurant));
		}

		TimeUnit.SECONDS.sleep(10); // Run for a while...
		exec.shutdownNow(); // Interrupt all tasks
    }

}