ReadWriteLock

最新推荐文章于 2025-08-04 22:00:33 发布

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最新推荐文章于 2025-08-04 22:00:33 发布

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分类专栏： JUC 文章标签： java juc

本文链接：https://blog.youkuaiyun.com/weixin_48426115/article/details/128294309

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本文通过一个简单的示例展示了读写锁（ReadWriteLock）在Java并发编程中的使用方法。介绍了如何利用读写锁来实现多线程环境中读操作的并发执行及写操作的互斥执行，从而提高程序效率。

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读的时候可以多个线程读取，写的时候只能一个线程写入

没有使用读写锁

package com.yuan.rw;


import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;



public class ReadWriteLockDemo {
    public static void main(String[] args) {
        MyCache myCache = new MyCache();

        for (int i = 1; i <= 5; i++) {
            final String temp = String.valueOf(i);
            new Thread(()->{
                myCache.put(temp,temp);
            },temp).start();
        }

        for (int i = 1; i <= 5; i++) {
            final String temp = String.valueOf(i);
            new Thread(()->{
                myCache.get(temp);
            },String.valueOf(i)).start();
        }
    }
}




class MyCache{
    private volatile Map<String, Object> map = new HashMap<>();

    //存，写
    public void put(String key,Object value){
        System.out.println(Thread.currentThread().getName() + "写入" + key);
        map.put(key, value);
        System.out.println(Thread.currentThread().getName() + "写入成功");
    }

    //取，读
    public void get(String key){
        System.out.println(Thread.currentThread().getName() + "读取" + key);
        map.get(key);
        System.out.println(Thread.currentThread().getName() + "读取成功");
    }

}

没有使用读写锁

package com.yuan.rw;


import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;



public class ReadWriteLockDemo {
    public static void main(String[] args) {
        MyCache myCache = new MyCache();
        for (int i = 1; i <= 5; i++) {
            final String temp = String.valueOf(i);
            new Thread(()->{
                myCache.put(temp,temp);
            },temp).start();
        }

        for (int i = 1; i <= 5; i++) {
            final String temp = String.valueOf(i);
            new Thread(()->{
                myCache.get(temp);
            },String.valueOf(i)).start();
        }
    }
}


class MyCacheLock{
    private volatile Map<String, Object> map = new HashMap<>();
    private ReadWriteLock readWriteLock = new ReentrantReadWriteLock();

    //存，写
    public void put(String key,Object value){
        readWriteLock.writeLock().lock();

        try {
            System.out.println(Thread.currentThread().getName() + "写入" + key);
            map.put(key, value);
            System.out.println(Thread.currentThread().getName() + "写入成功");
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            readWriteLock.writeLock().unlock();
        }

    }

    //取，读
    public void get(String key){
        readWriteLock.readLock().lock();
        try {
            System.out.println(Thread.currentThread().getName() + "读取" + key);
            map.get(key);
            System.out.println(Thread.currentThread().getName() + "读取成功");
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            readWriteLock.readLock().unlock();
        }
    }
}