Redis分布式锁的使用案例

news2024/9/22 1:18:27

一、引入依赖

<dependency>
<groupId>redis.clients</groupId>
<artifactId>jedis</artifactId>
<version>3.5.0</version>
</dependency>

二、工具类

package com.hl.redisdemo.util;

import redis.clients.jedis.Jedis;
import redis.clients.jedis.params.SetParams;

import java.util.Collections;

public class RedissonLockUtil {
    private static final Jedis jedis = new Jedis("localhost", 6379);

    /**
     * 可重入锁加锁
     * @param lockKey 锁的key
     * @param requestId 请求标识
     * @param expireTime 超时时间
     * @return 是否成功获取锁
     */
    public static boolean lock(String lockKey, String requestId, int expireTime) {
        SetParams params = new SetParams();
        params.nx().px(expireTime); // 设置nx和px参数，保证只在不存在该key时设置值，并设置过期时间
        String result = jedis.set(lockKey, requestId, params);
        return "OK".equalsIgnoreCase(result);
    }

    /**
     * 可重入锁解锁
     * @param lockKey 锁的key
     * @param requestId 请求标识
     * @return 是否成功释放锁
     */
    public static boolean unlock(String lockKey, String requestId) {
        String luaScript = "if redis.call('get', KEYS[1]) == ARGV[1] then return redis.call('del', KEYS[1]) else return 0 end";
        Object result = jedis.eval(luaScript, Collections.singletonList(lockKey), Collections.singletonList(requestId));
        Long RELEASE_SUCCESS = 1L;
        return RELEASE_SUCCESS.equals(result);
    }

    /**
     * 获取可重入锁
     * @param lockKey 锁的key
     * @param requestId 请求标识
     * @param expireTime 超时时间
     * @return 是否成功获取锁
     */
    public static boolean tryLock(String lockKey, String requestId, int expireTime) {
        SetParams params = new SetParams();
        params.nx().px(expireTime); // 设置nx和px参数，保证只在不存在该key时设置值，并设置过期时间
        String result = jedis.set(lockKey, requestId, params);
        return "OK".equalsIgnoreCase(result);
    }
}

三、测试代码

package com.hl.redisdemo.controller;

import com.hl.redisdemo.util.RedissonLockUtil;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.UUID;

/**
 * @author hulei
 * @date 2024/2/6 17:23
 */

@RestController
public class RedisDemoController {

    @RequestMapping("/redisTest")
    public String redisTest() throws InterruptedException {
        String str;
        String lockKey = "myLock";
        String requestId = UUID.randomUUID().toString(); // 生成唯一请求标识
        // 集群场景下，锁超时时间应该保证大于多数节点获取锁的时间
        //当发生在多数节点获取锁的时间大于锁超时时间时，获取到的锁在各节点早已超时失效，锁失效
        int expireTime = 5000; // 锁的过期时间为5秒,注意,
        // 尝试获取锁
        if (RedissonLockUtil.tryLock(lockKey, requestId, expireTime)) {
            System.out.println("获取到锁");
            // 执行业务逻辑
            Thread.sleep(1000);
            // 释放锁
            if (RedissonLockUtil.unlock(lockKey, requestId)) {
                System.out.println("释放锁成功");
                str = "释放锁成功";
            } else {
                System.out.println("释放锁失败");
                str = "释放锁失败";
            }
        } else {
            System.out.println("获取锁失败");
            str = "获取锁失败";
        }
        return str;
    }
}

测试结果分析：

1.正常测试结果