JUC 读写锁 ReadWriteLock

一、语法

private ReadWriteLock rwLock = new ReentrantReadWriteLock();
// 上锁
rwLock.writeLock().lock();
// 释放锁
rwLock.writeLock().unlock();

二、案例

存入、读取 map数据

package com.wt.readwrite;

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

/**
 * @Description: TODO
 * @Author: 1872428
 * @Date: 2025/6/2 8:53
 * @Version: 1.0
 **/

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

    // 保存
    public void save(String key, Object object){
        try {
            rwLock.writeLock().lock();
            System.out.println(Thread.currentThread().getName()+"正在写入数据" +key);
            map.put(key, object);
            TimeUnit.MICROSECONDS.sleep(300);
            System.out.println(Thread.currentThread().getName()+"写入完成" + key);
        } catch (InterruptedException e) {
            e.printStackTrace();
        } finally {
            rwLock.writeLock().unlock();
        }

    }
    // 获取
    public Object getData(String key){

        Object result = null;
        try {
            rwLock.readLock().lock();
            System.out.println(Thread.currentThread().getName()+"正在读取数据" + key);
            result = map.get(key);
            TimeUnit.MICROSECONDS.sleep(300);
            System.out.println(Thread.currentThread().getName()+"读取完成" + key);
        } catch (InterruptedException e) {
            e.printStackTrace();
        } finally {
            rwLock.readLock().unlock();
        }
        return result;
    }
}
public class Demon {
    public static void main(String[] args) {
        OperationData operationData = new OperationData();
        // 存
        for (int i = 0; i < 5; i++) {
            final int num = i;
            new Thread(()->{
                operationData.save(num + "", num +"");
            }, "AA").start();
        }
        try {
            TimeUnit.MICROSECONDS.sleep(300);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        // 取
        for (int i = 0; i < 5; i++) {
            final int num = i;
            new Thread(()->{
                operationData.getData(num + "");
            }, "BB").start();
        }
    }
}