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Springboot redis Vue 秒杀

Atlantide 人气:0

1、Redis简介

Redis是一个开源的key-value存储系统。

Redis的五种基本类型:String(字符串),list(链表),set(集合),zset(有序集合),hash,stream(Redis5.0后的新数据结构)

这些数据类型都支持push/pop、add/remove及取交集并集和差集及更丰富的操作,而且这些操作都是原子性的。

Redis的应用场景为配合关系型数据库做高速缓存,降低数据库IO

需要注意的是,Redis是单线程的,如果一次批量处理命令过多,会造成Redis阻塞或网络拥塞(传输数据量大)

2、实现代码

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.2.1.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>org.example</groupId>
    <artifactId>seckill</artifactId>
    <version>1.0-SNAPSHOT</version>
    <properties>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-starter-test -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <version>2.2.1.RELEASE</version>
            <scope>test</scope>
        </dependency>

        <!-- redis -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-redis</artifactId>
        </dependency>

        <!-- spring2.X集成redis所需common-pool2-->
        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-pool2</artifactId>
            <version>2.6.0</version>
        </dependency>

        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.24</version>
        </dependency>

    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <fork>true</fork>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>

application.properties.xml

#Redis服务器地址
spring.redis.host=192.168.1.2
#Redis服务器连接端口
spring.redis.port=6379
#Redis数据库索引(默认为0)
spring.redis.database=0
#连接超时时间(毫秒)
spring.redis.timeout=1800000
#连接池最大连接数(使用负值表示没有限制)
spring.redis.lettuce.pool.max-active=20
#最大阻塞等待时间(负数表示没限制)
spring.redis.lettuce.pool.max-wait=-1
#连接池中的最大空闲连接
spring.redis.lettuce.pool.max-idle=5
#连接池中的最小空闲连接
spring.redis.lettuce.pool.min-idle=0
# 关闭超时时间
#pring.redis.lettuce.shutdown-timeout=100
#配置spring启动端口号
server.port=8080

前端界面

seckillpage.html

<!DOCTYPE html>
<html lang="en" xmlns:v-on="http://www.w3.org/1999/xhtml" xmlns:v-bind="http://www.w3.org/1999/xhtml">
<head>
    <meta charset="UTF-8">
    <title>redis秒杀</title>
</head>
<body>
<!-- 开发环境版本,包含了有帮助的命令行警告 -->
<script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
<!-- 官网提供的 axios 在线地址 -->
<script src="https://cdn.bootcdn.net/ajax/libs/axios/0.20.0-0/axios.min.js"></script>
<div id="app">
    <h1>商品1元秒杀</h1>
    <!-- 左箭头 -->
    <input type="button" value="<" v-on:click="prov" v-show="this.index>-1"/>
    <img v-bind:src="imgArr[index]" width="200px" />
    <!-- 右箭头 -->
    <input type="button" value=">" v-on:click="next" v-show="this.index<2"/><br>
    <input type="button" v-on:click="seckill" value="秒 杀"/>
</div>
<script>
    var app = new Vue({
        el: "#app",
        data: {
            productId: "01234",
            imgArr:[
                "/image/phone1.png",
                "/image/phone2.png",
                "/image/phone3.png",
            ],
            index:0
        },
        methods: {
            seckill: function () {
                let param = new URLSearchParams()
                param.append('productId', this.productId)
                param.append('index', this.index)
                axios({
                    method: 'post',
                    url: 'http://192.168.1.6:8080/index/doSeckill',
                    data: param
                }).then(function (response) {
               
                    if (response.data == true) {
                        alert("秒杀成功");
                    } else {
                        alert("抢光了");
                    }
                 
                },
                    function(error){
                    alert("发生错误");
                });

            },

            prov:function(){
                this.index--;
            },
            next:function(){
                this.index++;
            }
        }
    });

</script>
</body>
</html>

相关配置类

Redis配置类

RedisConfig.java

package com.springboot_redis_seckill.config;

import com.fasterxml.jackson.annotation.JsonAutoDetect;
import com.fasterxml.jackson.annotation.PropertyAccessor;
import com.fasterxml.jackson.databind.ObjectMapper;
import org.springframework.cache.CacheManager;
import org.springframework.cache.annotation.CachingConfigurerSupport;
import org.springframework.cache.annotation.EnableCaching;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.redis.cache.RedisCacheConfiguration;
import org.springframework.data.redis.cache.RedisCacheManager;
import org.springframework.data.redis.connection.RedisConnectionFactory;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.serializer.Jackson2JsonRedisSerializer;
import org.springframework.data.redis.serializer.RedisSerializationContext;
import org.springframework.data.redis.serializer.RedisSerializer;
import org.springframework.data.redis.serializer.StringRedisSerializer;

import java.time.Duration;

/**
 * @author WuL2
 * @create 2021-05-27 14:26
 * @desc
 **/
@EnableCaching
@Configuration
public class RedisConfig extends CachingConfigurerSupport {

    @Bean
    public RedisTemplate<String, Object> redisTemplate(RedisConnectionFactory factory) {
        RedisTemplate<String, Object> template = new RedisTemplate<>();
        RedisSerializer<String> redisSerializer = new StringRedisSerializer();
        Jackson2JsonRedisSerializer jackson2JsonRedisSerializer = new Jackson2JsonRedisSerializer(Object.class);
        ObjectMapper om = new ObjectMapper();
        om.setVisibility(PropertyAccessor.ALL, JsonAutoDetect.Visibility.ANY);
        om.enableDefaultTyping(ObjectMapper.DefaultTyping.NON_FINAL);
        jackson2JsonRedisSerializer.setObjectMapper(om);
        template.setConnectionFactory(factory);
        template.setKeySerializer(redisSerializer); //key序列化方式
        template.setValueSerializer(jackson2JsonRedisSerializer); //value序列化
        template.setHashValueSerializer(jackson2JsonRedisSerializer); //value hashmap序列化
        return template;
    }

    @Bean(name = "cacheManager")
    public CacheManager cacheManager(RedisConnectionFactory factory) {
        RedisSerializer<String> redisSerializer = new StringRedisSerializer();
        Jackson2JsonRedisSerializer jackson2JsonRedisSerializer = new Jackson2JsonRedisSerializer(Object.class);
        //解决查询缓存转换异常的问题
        ObjectMapper om = new ObjectMapper();
        om.setVisibility(PropertyAccessor.ALL, JsonAutoDetect.Visibility.ANY);
        om.enableDefaultTyping(ObjectMapper.DefaultTyping.NON_FINAL);
        jackson2JsonRedisSerializer.setObjectMapper(om);
        // 配置序列化(解决乱码的问题),过期时间600秒
        RedisCacheConfiguration config = RedisCacheConfiguration.defaultCacheConfig()
                .entryTtl(Duration.ofSeconds(600))
                .serializeKeysWith(RedisSerializationContext.SerializationPair.fromSerializer(redisSerializer))
                .serializeValuesWith(RedisSerializationContext.SerializationPair.fromSerializer(jackson2JsonRedisSerializer))
                .disableCachingNullValues();
        RedisCacheManager cacheManager = RedisCacheManager.builder(factory)
                .cacheDefaults(config)
                .build();
        return cacheManager;
    }
}

配置Vue获取后端接口数据时出现的跨域请求问题。

CorsConfig.java

package com.springboot_redis_seckill.config;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.cors.CorsConfiguration;
import org.springframework.web.cors.UrlBasedCorsConfigurationSource;
import org.springframework.web.filter.CorsFilter;


/**
 * @author: wu linchun
 * @time: 2021/5/28 22:22
 * @description: 解决跨域问题(接口是http,而axios一般请求的是https。从https到http是跨域,因此要配置跨域请求)
 */

@Configuration
public class CorsConfig {
    private CorsConfiguration buildConfig() {
        CorsConfiguration corsConfiguration = new CorsConfiguration();
        corsConfiguration.addAllowedOrigin("*"); //允许任何域名
        corsConfiguration.addAllowedHeader("*"); //允许任何头
        corsConfiguration.addAllowedMethod("*"); //允许任何方法
        return corsConfiguration;
    }

    @Bean
    public CorsFilter corsFilter() {
        UrlBasedCorsConfigurationSource source = new UrlBasedCorsConfigurationSource();
        source.registerCorsConfiguration("/**", buildConfig()); //注册
        return new CorsFilter(source);
    }

}

服务层

SecKillService.java

package com.springboot_redis_seckill.service;

public interface SecKillService {
    public boolean doSecKill(String uid,String productId);
}

SecKillServiceImpl.java

package com.springboot_redis_seckill.service.impl;

import com.springboot_redis_seckill.service.SecKillService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.stereotype.Service;

/**
 * @author WuL2
 * @create 2021-05-27 14:53
 * @desc
 **/
@Service
public class SecKillServiceImpl implements SecKillService {
    @Autowired
    @Qualifier("redisTemplate")
    private RedisTemplate redisTemplate;

    @Override
    public synchronized boolean doSecKill(String uid, String productId) {
        //1、uid和productId非空判断
        if (uid == null || productId == null) {
            return false;
        }

        //2、拼接key
        String kcKey = "sk:" + productId + ":qt";   //库存
        String userKey = "sk:" + productId + ":user";  //秒杀成功的用户

        //3、获取库存
        String kc = String.valueOf(redisTemplate.opsForValue().get(kcKey)) ;
        if (kc == null) {
            System.out.println("秒杀还没有开始,请等待");
            return false;
        }

        //4、判断用户是否已经秒杀成功过了
        if (redisTemplate.opsForSet().isMember(userKey, uid)) {
            System.out.println("已秒杀成功,不能重复秒杀");
            return false;
        }
        //5、如果库存数量小于1,秒杀结束
        if (Integer.parseInt(kc) <=0) {
            System.out.println("秒杀结束");
            return false;
        }

        //6、秒杀过程
        redisTemplate.opsForValue().decrement(kcKey);  //库存数量减1
        redisTemplate.opsForSet().add(userKey, uid);
        System.out.println("秒杀成功。。。");
        return true;
    }
}

控制层

package com.springboot_redis_seckill.controller;

import com.alibaba.fastjson.JSONObject;
import com.springboot_redis_seckill.service.SecKillService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Random;

/**
 * @author WuL2
 * @create 2021-05-27 14:28
 * @desc
 **/
@Controller
@RequestMapping("/index")
public class MyController {
    @Autowired
    @Qualifier("secKillServiceImpl")
    private SecKillService secKillService;

    @RequestMapping(value = {"/seckillpage"}, method = RequestMethod.GET)
    public String seckillpage() {
        return "/html/seckillpage.html";
    }


    @RequestMapping(value = {"/doSeckill"}, method = RequestMethod.POST)
    @ResponseBody  //自动返回json格式的数据
    public Object doSeckill(HttpServletRequest request, HttpServletResponse response) {
        System.out.println("doSeckill");
        String productId = request.getParameter("productId");  
        String index = request.getParameter("index");
        System.out.println(productId+index);  //拼接成为商品ID
        int id = new Random().nextInt(50000);  //使用随机数生成用户ID
        String uid = String.valueOf(id) + " ";
        boolean flag = secKillService.doSecKill(uid, productId+index);
        System.out.println(flag);
        return flag;
    }
}

启动类

RunApplication.java

package com.springboot_redis_seckill;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

/**
 * @author WuL2
 * @create 2021-05-27 14:32
 * @desc
 **/
@SpringBootApplication
public class RunApplication {
    public static void main(String[] args) {
        SpringApplication.run(RunApplication.class, args);
    }
}

3、启动步骤

因为一共有三件商品要秒杀,所以在redis里面设置三个商品的库存数量。这里数量都设置为10。

127.0.0.1:6379> set sk:012340:qt 10
OK
127.0.0.1:6379> set sk:012341:qt 10
OK
127.0.0.1:6379> set sk:012342:qt 10
OK

要确保redis能够被访问,要确保关闭linux的防火墙,以及关闭redis的保护模式。

vim redis.conf   --打开redis配置
 
service iptables stop   --关闭防火墙
 
 
//关闭redis保护模式
redis-cli    --进入redis客户端
config set protected-mode "no"   --配置里面关闭redis保护模式(只是进入redis.conf把protected-mode变为no是不行的,还要加一句config set protected-mode "no"

启动springboot项目

秒杀成功后,该商品在redis中的数量就减1。

当数量减为0时,则提示“抢光了”。

4、使用ab进行并发测试

如果是centOS 6版本的linux都是默认按照了ab工具的。

如果没有安装ab工具,可在linux终端用命令联网下载安装。

yum install httpd-tools

安装完成后,就可以使用ab工具进行并发测试了。

在linux终端输入如下命令:

ab -n 2000  -c 200 -p '/root/Desktop/post.txt' -T 'application/x-www-form-urlencoded' 'http://192.168.1.6:8080/index/doSeckill/'

012341这个商品库存变为0了

5、线程安全

为了防止出现“超买”的现象,需要让操作redis的方法是线程安全的(即在方法上加上一个“悲观锁”synchronized)。

如果不加synchronized就会出现“超买”现象,即redis库存会出现负数

之所以产生这种现象是由于并发导致多个用户同时调用了doSecKill()方法,多个用户同时修改了redis中的sk:012342:qt的值,但暂时都没有提交存入到redis中去。等到后来一起提交,导致了sk:012342:qt的值被修改了多次,因此会出现负数。

因此在doSecKill()方法加上悲观锁,用户调用该方法就对该方法加锁,修改了sk:012342:qt的值后并提交存入redis中之后,才会释放锁。其他用户才能得到锁并操作该方法。

6、总结

redis作为一种Nosql的非关系型数据库,因为其单实例,简单高效的特性通常会被作为其他关系型数据库的高速缓存。尤其是在秒杀这样的高并发操作。先将要秒杀的商品信息从数据库读入到redis中,秒杀的过程实际上是在与redis进行交互。等秒杀完成后再将秒杀的结果存入数据库。可以有效降低降低数据库IO,防止数据库宕机。

7、参考资料

https://www.bilibili.com/video/BV1Rv41177Af?p=27

https://www.cnblogs.com/taiyonghai/p/5810150.html

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