redis秒杀案例，跟着b站尚硅谷老师学习

一、使用redis的事务解决秒杀问题，但是会产生库存遗留问题

二、使用lua脚本解决秒杀问题

0、使用lua脚本的优势

1、具体使用的service层代码

package com.bear.service;

import com.bear.config.JedisPoolUtil;
import org.springframework.stereotype.Service;
import redis.clients.jedis.Jedis;
import redis.clients.jedis.JedisPool;

import java.io.IOException;

/** * <简述> * <详细描述> * * @author LiuShanshan * @version $Id$ */
@Service
public class SewckillServiceTwo {
    

    String secKillScript ="local userid=KEYS[1];\r\n" +
            "local prodid=KEYS[2];\r\n" +
            "local qtkey='sk:'..prodid..\":qt\";\r\n" +
            "local usersKey='sk:'..prodid..\":usr\";\r\n" +
            "local userExists=redis.call(\"sismember\",usersKey,userid);\r\n" +
            "if tonumber(userExists)==1 then \r\n" +
            " return 2;\r\n" +
            "end\r\n" +
            "local num= redis.call(\"get\" ,qtkey);\r\n" +
            "if tonumber(num)<=0 then \r\n" +
            " return 0;\r\n" +
            "else \r\n" +
            " redis.call(\"decr\",qtkey);\r\n" +
            " redis.call(\"sadd\",usersKey,userid);\r\n" +
            "end\r\n" +
            "return 1" ;


    public boolean doSecKill(String prodid,String uid) throws IOException {
    

        JedisPool jedispool =  JedisPoolUtil.getJedisPoolInstance();
        Jedis jedis=jedispool.getResource();

        //String sha1= .secKillScript;
        String sha1=  jedis.scriptLoad(secKillScript);
        Object result= jedis.evalsha(sha1, 2, uid,prodid);

        String reString=String.valueOf(result);
        if ("0".equals( reString )  ) {
    
            System.err.println("已抢空！！");
        }else if("1".equals( reString )  )  {
    
            System.out.println("抢购成功！！！！");
        }else if("2".equals( reString )  )  {
    
            System.err.println("该用户已抢过！！");
        }else{
    
            System.err.println("抢购异常！！");
        }
        jedis.close();
        return true;
    }
}

2、controller层

    /** * 秒杀测试使用lua脚本 * @return */
    @GetMapping("/seckill/test")
    public Boolean seckillTest() throws IOException {
    
        // 固定商品id ；// 自动生成的用户id
        return sewckillServiceTwo.doSecKill("1001", Long.toString(System.currentTimeMillis()));
    }