redis分布式锁

https://blog.youkuaiyun.com/wuzhiwei549/article/details/80692278

package com.my.config.redis;


import redis.clients.jedis.Jedis;

import java.util.Collections;

public class RedisTool {

    private static final String LOCK_SUCCESS = "OK";
    private static final String SET_IF_NOT_EXIST = "NX";
    private static final String SET_WITH_EXPIRE_TIME = "PX";

    /**
    redis分布式锁 
	加锁条件
	1给锁设置一个失效时间       ---------->避免死锁
	2加锁时每个节点产生一个随机数--------->避免锁误删
	3写入随机值与失效时间必须是同时进行 --->保证枷锁是同步的
     * 尝试获取分布式锁
     * @param jedis Redis客户端
     * @param lockKey 锁
     * @param requestId 请求标识 随机字符串生成
     * @param expireTime 超期时间
     * @return 是否获取成功
     */
    public static boolean tryGetDistributedLock(Jedis jedis, String lockKey, String requestId, int expireTime) {

        String result = jedis.set(lockKey, requestId, SET_IF_NOT_EXIST, SET_WITH_EXPIRE_TIME, expireTime);

        if (LOCK_SUCCESS.equals(result)) {
            return true;
        }
        return false;
    }

    private static final Long RELEASE_SUCCESS = 1L;
    /**
     * 释放分布式锁
     * @param jedis Redis客户端
     * @param lockKey 锁
     * @param requestId 请求标识
     * @return 是否释放成功
     */
    public static boolean releaseDistributedLock(Jedis jedis, String lockKey, String requestId) {
        String script = "if redis.call('get', KEYS[1]) == ARGV[1] then return redis.call('del', KEYS[1]) else return 0 end";
        Object result = jedis.eval(script, Collections.singletonList(lockKey), Collections.singletonList(requestId));
        if (RELEASE_SUCCESS.equals(result)) {
            return true;
        }
        return false;
    }
}