Redis实现存取数据+数据存取

﹏ヽ暗。殇╰゛Y 2022-01-06 22:25 327阅读 0赞

添加依赖：

<dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-databind</artifactId>
        <version>2.9.7</version>
    </dependency>
    
     
            <dependency>
                <groupId>org.springframework.data</groupId>
                <artifactId>spring-data-redis</artifactId>
                <version>2.1.3.RELEASE</version>
     </de

Mapper接口：

package com.nf147.sim.mapper;
    
    import com.nf147.sim.entity.News;
    
    import java.util.List;
    
    public interface NewsMapper {
        List<News> query();
        void add(News news);
    }

映射文件：

<?xml version="1.0" encoding="UTF-8"?>
    <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
    <mapper namespace="com.nf147.sim.mapper.NewsMapper">
    
        <resultMap id="BaseResultMap" type="com.nf147.sim.entity.News">
            <id column="id" jdbcType="INTEGER" property="id" />
            <result column="title" jdbcType="VARCHAR" property="title" />
            <result column="body" jdbcType="VARCHAR" property="body" />
        </resultMap>
    
        <select id="query" resultType="com.nf147.sim.entity.News">
            select id ,title,body from news
        </select>
    
        <select id="selectAll" resultType="com.nf147.sim.entity.News">
              select id ,title,body from news
        </select>
    
        <insert id="add" keyProperty="id" useGeneratedKeys="true">
            insert into news (title,body) values (#{title},#{body})
        </insert>
    
    </mapper>

服务接口：

package com.nf147.sim.service;
    
    import com.nf147.sim.entity.News;
    import redis.clients.jedis.Jedis;
    
    import java.io.IOException;
    import java.util.List;
    
    public interface NewsService {
        List<News> selectAll() throws IOException;void add (News news);
    }

实现：

package com.nf147.sim.service.impl;
    
    import com.fasterxml.jackson.core.type.TypeReference;
    import com.fasterxml.jackson.databind.ObjectMapper;
    import com.nf147.sim.entity.News;
    import com.nf147.sim.mapper.NewsMapper;
    import com.nf147.sim.service.NewsService;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.stereotype.Service;
    import redis.clients.jedis.Jedis;
    
    import java.io.IOException;
    import java.util.List;
    
    @Service
    public class NewsServiceImpl implements NewsService {
    
        @Autowired
        private NewsMapper mapper;
    
        @Override
            public List<News> selectAll() throws IOException {
    
                Jedis jedis =new Jedis();
                String key = "listNews";
    
                ObjectMapper on = new ObjectMapper();  //josn
    
            if (jedis.exists(key)){    　　　　　　　　　　　　//判断缓存有没有存在key
                System.out.println("从缓存中取出数据...");
                return on.readValue(jedis.get(key),new TypeReference<List<News>>(){});  //如果有就从缓存里面取数据
            }
    
    　　　　　//没有则从数据库去取
            List<News> news = mapper.query();
            jedis.set(key,on.writeValueAsString(news));  //然后设置键和数据
            return news;                                //返回
        }
    
        @Override
        public void add(News news) {  //每次添加时判短键是否存在，如果存在首先删除
            Jedis jedis = new Jedis();
            String key="listNews";
            if(jedis.exists(key))
                jedis.del(key);
            mapper.add(news);
        }
    
    
    }

测试：

package com.nf147.sim.service.impl;
    
    import com.fasterxml.jackson.core.JsonProcessingException;
    import com.fasterxml.jackson.core.type.TypeReference;
    import com.fasterxml.jackson.databind.ObjectMapper;
    import com.google.gson.Gson;
    import com.google.gson.reflect.TypeToken;
    import com.nf147.sim.configuration.RootConfig;
    import com.nf147.sim.entity.News;
    import com.nf147.sim.mapper.NewsMapper;
    import com.nf147.sim.service.NewsService;
    import org.junit.Test;
    import org.junit.runner.RunWith;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.test.context.ContextConfiguration;
    import org.springframework.test.context.junit4.SpringRunner;
    import redis.clients.jedis.Jedis;
    
    import java.io.*;
    import java.lang.reflect.Type;
    import java.util.ArrayList;
    import java.util.Arrays;
    import java.util.List;
    
    
    @RunWith(SpringRunner.class)
    @ContextConfiguration(classes = RootConfig.class)
    public class NewsServiceImplTest {
    
        @Autowired
        private NewsServiceImpl NewsServiceImpl;
    
        @Test
        public void selectAll() throws IOException {
            List<News> news = NewsServiceImpl.selectAll();
            System.out.println(news);
        }
    
    
        }
    }

结果：![1470521-20181228110114036-1476235473.gif][]

转载于:https://www.cnblogs.com/nongzihong/p/10188112.html

[1470521-20181228110114036-1476235473.gif]: /images/20211227/99f0bdf485b24da8980f4ec3957bc357.png