Redis实现存取数据+数据存取

提示：扫一扫查出行
【扫一扫了解最新限行尾号】
复制提示

添加依赖：

<dependency>

    <groupId>com.fasterxml.jackson.core</groupId>

    <artifactId>jackson-databind</artifactId>

    <version>2.9.7</version>

</dependency>

 <!-- https://mvnrepository.com/artifact/org.springframework.data/spring-data-redis -->

        <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);

    }

    }

}