Java基础 生产者和消费者问题

[俺是小王子]

这是一道Java基础题，最近我也是夯实基础才偶然发现

源码来源 Java SE doc文档示例程序

我放到我笔记本上一运行发现死锁了。。。。Java并发一直是我头疼的问题，解释不清；大CSDN人才济济，大家能否帮小弟想出一种可能性，到底问题出在哪。。。。。

知识领域：Java并发编程

题目类型：低级生产者消费者模型

运行环境：Win8 + Eclipse + 四核CPU + 4G RAM （大家别笑，Linux环境还真没怎么用过。。。暂时还没那需求。。。）

代码：

Drop类，共享类 代表生产者和消费者共享的东西

/**
 * Copyright (c) 2014  All rights reserved.
 * You can use all code for free just for study.
 * If you want to use this code for business. please contact me. Thank you.
 * email:<a href="mailto:[e-mail]">[e-mail]</a>
 */
package com.test.study;

/**
 * @author WangCheng
 * 2014年11月17日 下午11:19:52
 * TODO
 */
public class Drop {
    // Message sent from producer
    // to consumer.
    private String message;
    // True if consumer should wait
    // for producer to send message,
    // false if producer should wait for
    // consumer to retrieve message.
    private boolean empty = true;

    public synchronized String take() {
        // Wait until message is
        // available.
        while (empty) {
            try {
                wait();
            } catch (InterruptedException e) {}
        }
        // Toggle status.
        empty = true;
        // Notify producer that
        // status has changed.
        notifyAll();
        return message;
    }

    public synchronized void put(String message) {
        // Wait until message has
        // been retrieved.
        while (!empty) {
            try { 
                wait();
            } catch (InterruptedException e) {}
        }
        // Toggle status.
        empty = false;
        // Store message.
        this.message = message;
        // Notify consumer that status
        // has changed.
        notifyAll();
    }
}

Producter 类 生产者

/**
 * Copyright (c) 2014  All rights reserved.
 * You can use all code for free just for study.
 * If you want to use this code for business. please contact me. Thank you.
 * email:<a href="mailto:[e-mail]">[e-mail]</a>
 */
package com.test.study;

import java.util.Random;

/**
 * @author WangCheng
 * 2014年11月17日 下午11:28:36
 * TODO
 */
public class Producter implements Runnable{
    private Drop drop;

    public Producter(Drop drop) {
        this.drop = drop;
    }

    public void run() {
        String importantInfo[] = {
            "Mares eat oats",
            "Does eat oats",
            "Little lambs eat ivy",
            "A kid will eat ivy too"
        };
        Random random = new Random();

        for (int i = 0;
             i < importantInfo.length;
             i++) {
            drop.put(importantInfo[i]);
            try {
                Thread.sleep(random.nextInt(5000));
            } catch (InterruptedException e) {}
        }
        drop.put("DONE");
    }
}

Consumer 类 消费者

/**
 * Copyright (c) 2014  All rights reserved.
 * You can use all code for free just for study.
 * If you want to use this code for business. please contact me. Thank you.
 * email:<a href="mailto:[e-mail]">[e-mail]</a>
 */
package com.test.study;

import java.util.Random;

/**
 * @author WangCheng
 * 2014年11月17日 下午11:35:07
 * TODO
 */
public class Consumer implements Runnable{
    private Drop drop;

    public Consumer(Drop drop) {
        this.drop = drop;
    }

    public void run() {
        Random random = new Random();
        for (String message = drop.take();
             ! message.equals("DONE");
             message = drop.take()) {
            System.out.format("MESSAGE RECEIVED: %s%n", message);
            try {
                Thread.sleep(random.nextInt(5000));
            } catch (InterruptedException e) {}
        }
    }
}

Main函数

/**
 * Copyright (c) 2014  All rights reserved.
 * You can use all code for free just for study.
 * If you want to use this code for business. please contact me. Thank you.
 * email:<a href="mailto:[e-mail]">[e-mail]</a>
 */
package com.test.study;

/**
 * @author WangCheng
 * 2014年11月17日 下午11:39:33
 * TODO
 */
public class ProductAndConsumerDemo {
	public static void main(String[] args) {
		Drop drop = new Drop();
		(new Thread(new Producter(drop))).start();
		(new Thread(new Producter(drop))).start();
	}

}

一开始我是照葫芦画瓢，发现我的死锁了，索性copy它的代码，发现同样如此。。。。。

代码出处 https://docs.oracle.com/javase/tutorial/essential/concurrency/guardmeth.html

[yktd26]

这个你得有消费者去take来解锁啊 你main里面开两个生产者，生产一个就锁住了....

[ghx287524027]

楼主，你代码写错了吧，跟你链接中的代码不一样，比如main函数： public class ProducerConsumerExample { public static void main(String[] args) { Drop drop = new Drop(); (new Thread(new Producer(drop))).start(); (new Thread(new Consumer(drop))).start(); } }

[俺是小王子]

囧大了