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java生产者/消费者模式实现——一生产者一消费者(操作值)

时间:2016-02-28 12:19:28      阅读:126      评论:0      收藏:0      [点我收藏+]

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 胶多不粘话多不甜,直接上代码:

生产者类:

/**
 * Created by 51304 on 2016/2/28.
 */
public class P {
    private String lock;
    public P(String lock){
        this.lock = lock;
    }

    public void setValue(){
        try{
            synchronized (this.lock){
                if(!ValueObject.value.equals("")){
                    lock.wait();
                }
                String value = System.currentTimeMillis() + "_" +
                        System.nanoTime();
                System.out.println("set value is " + value);
                ValueObject.value = value;
                lock.notify();
            }
        } catch (InterruptedException e){
            e.printStackTrace();
        }
    }
}

消费者类:

import com.sun.org.apache.xpath.internal.SourceTree;

/**
 * Created by 51304 on 2016/2/28.
 */
public class C {
    private String lock;
    public C(String lock){
        this.lock = lock;
    }

    public void getValue(){
        try{
            synchronized (this.lock){
                if(ValueObject.value.equals("")){
                    this.lock.wait();
                }
                System.out.println("get value is " + ValueObject.value);
                ValueObject.value = "";
                this.lock.notify();
            }
        } catch (InterruptedException e){
            e.printStackTrace();
        }
    }
}

存储值的对象:

/**
 * Created by 51304 on 2016/2/28.
 */
public class ValueObject {
    public static String value = "";
}

生产者线程:

/**
 * Created by 51304 on 2016/2/28.
 */
public class ThreadP extends Thread {
    private P p;
    public ThreadP(P p){
        this.p = p;
    }

    @Override
    public void run(){
        while (true){
            p.setValue();
        }
    }
}

消费者线程:

/**
 * Created by 51304 on 2016/2/28.
 */
public class ThreadC extends Thread {
    private C c;
    public ThreadC(C c){
        this.c = c;
    }

    @Override
    public void run(){
        while (true){
            c.getValue();
        }
    }
}

main方法:

/**
 * Created by 51304 on 2016/2/28.
 */
public class TestMain {
    public static void main(String[] args) {
        String lock = new String("");
        P p = new P(lock);
        C c = new C(lock);

        ThreadP threadP =new ThreadP(p);
        ThreadC threadC = new ThreadC(c);

        threadP.start();
        threadC.start();
    }
}

运行截图:

技术分享

思考:如果多生产者和多消费者程序能正常工作吗?

答案是:程序会出现假死,也就是所有线程都停留在等待状态。出现这个现象的原因是,多生产者模式下notify()通知的线程还是生产者(选择通知那个线程时随机的,但只会通知一个),同理消费者也一样。当然解决的办法很明显使用notifyall().

java生产者/消费者模式实现——一生产者一消费者(操作值)

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原文地址:http://www.cnblogs.com/maxiaofang/p/5224262.html

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