JUC 读写锁 锁降级 写锁降级为读锁

一、注意

写锁可以降级为读锁，读锁不能升级为写锁

二、过程

1、写锁

2、读锁

3、释放写锁

4、释放读锁

三、案例

package com.wt.readwrite;

import java.util.concurrent.locks.ReentrantReadWriteLock;

/**
 * @Description: TODO
 * @Author: 1872428
 * @Date: 2025/6/2 10:46
 * @Version: 1.0
 **/
public class Demon02 {

    public static void main(String[] args) {
        ReentrantReadWriteLock readWriteLock = new ReentrantReadWriteLock();
        // 写锁
        ReentrantReadWriteLock.WriteLock writeLock = readWriteLock.writeLock();
        // 读锁
        ReentrantReadWriteLock.ReadLock readLock = readWriteLock.readLock();
        // 1.写锁
        writeLock.lock();
        System.out.println("abc");
        // 2.写锁
        readLock.lock();
        System.out.println("123");
        // 3.释放写锁
        writeLock.unlock();
        // 4.释放读锁
        readLock.unlock();
    }
}