Mybatis使用Redis替代二级缓存

水深无声 2024-04-19 13:10 75阅读 0赞

## 1、案例介绍 ##

将Mybatis查询数据库的结果，以键值对的形式存入Redis数据库，替代了Mybatis中的二级缓存。查询同样操作时，可以直接去Redis中读取结果，提高效率。

## 2、案例实现 ##

#### 2.1 导入项目依赖 ####

<dependency>
          <groupId>redis.clients</groupId>
          <artifactId>jedis</artifactId>
          <version>3.0.1</version>
        </dependency>
    
        <dependency>
          <groupId>org.mybatis</groupId>
          <artifactId>mybatis</artifactId>
          <version>3.4.6</version>
        </dependency>
    
        <dependency>
          <groupId>mysql</groupId>
          <artifactId>mysql-connector-java</artifactId>
          <version>5.1.38</version>
        </dependency>
    
    
        <dependency>
          <groupId>log4j</groupId>
          <artifactId>log4j</artifactId>
          <version>1.2.12</version>
        </dependency>
        <dependency>
          <groupId>org.slf4j</groupId>
          <artifactId>slf4j-api</artifactId>
          <version>1.7.25</version>
        </dependency>
        <dependency>
          <groupId>org.slf4j</groupId>
          <artifactId>slf4j-log4j12</artifactId>
          <version>1.7.25</version>
          <scope>test</scope>
        </dependency>
    
    
        
        <dependency>
          <groupId>org.mybatis.caches</groupId>
          <artifactId>mybatis-redis</artifactId>
          <version>1.0.0-beta2</version>
        </dependency>
    
    
        <dependency>
          <groupId>junit</groupId>
          <artifactId>junit</artifactId>
          <version>4.12</version>
        </dependency>

#### 2.2 准备实体类和数据库 ####

**实体类一定要实现序列化接口**（关闭Redis时，数据从内存保存到磁盘中）

public class User implements Serializable{
    
    
        private Integer id;
        private String name;
        private Integer age;
        private Date birthday;
        private BigDecimal salary;
        }

![在这里插入图片描述][20190918171220989.png]

#### 2.3 准备Mybatis相关类 ####

（1）创建mapper接口  
（2）创建Mybatis.xml

<?xml version="1.0" encoding="UTF-8" ?>
    <!DOCTYPE configuration
            PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
            "http://mybatis.org/dtd/mybatis-3-config.dtd">
    
    
    <configuration>
    
    
        <environments default="development">
            <environment id="development">
    
                <transactionManager type="JDBC"/>
                
                <dataSource type="POOLED">
                    <property name="driver" value="com.mysql.jdbc.Driver"/>
                    <property name="url" value="jdbc:mysql:///person"/>
                    <property name="username" value="root"/>
                    <property name="password" value="xxx"/>
                </dataSource>
            </environment>
        </environments>
    
        <mappers>
            <mapper resource="com/project/Redis/mapper/usermapper.xml"/>
        </mappers>
    </configuration>

**（3）创建接口映射文件**  
**将二级缓存类型修改为RedisCache类**

<?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.project.Redis.project.mapper.UserMapper">
        
    
        
        
        <cache type="org.mybatis.caches.redis.RedisCache"/>
    
    
        <select id="get" resultType="com.project.Redis.project.bean.User">
    
            select * from user where id = #{id}
    
        </select>
    
    
    
    </mapper>

#### 2.4 创建jedis工具类（Redis连接池对象） ####

package com.project.Redis.utils;
    
    import redis.clients.jedis.Jedis;
    import redis.clients.jedis.JedisPool;
    import redis.clients.jedis.JedisPoolConfig;
    
    // jedis就是一款java连接redis的客户端工具,工具类返回一个redis对象
    public class JedisUtil {
    
        private static JedisPool pool = null;
    
        static {
            JedisPoolConfig config = new JedisPoolConfig();
            config.setMaxIdle(10);
            config.setMaxTotal(50);
            config.setMinIdle(5);
            pool=  new JedisPool(config,"127.0.0.1",6379);
        }
    
    
        public static Jedis getJedis(){
            return pool.getResource();
        }
    }

#### 2.5 测试 ####

public class App {
    
    
        @Test
        public void testCache() throws Exception{
    
            SqlSession session = MybatisUtil.getSession();
            UserMapper mapper = session.getMapper(UserMapper.class);
            User user = mapper.get(1);
            session.commit();
            session.close();
            System.out.println(user);
    
            System.out.println("===========================");
    
            SqlSession session2 = MybatisUtil.getSession();
            UserMapper mapper2 = session2.getMapper(UserMapper.class);
            User user2 = mapper2.get(1);
            session2.commit();
            session2.close();
            System.out.println(user2);
    
    
        }
    
    }

#### 2.6 结果 ####

可以看到执行两条同样的查询语句，查询只执行了一次，第二次直接从缓存中读取结果。  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDc4NDY3Mw_size_16_color_FFFFFF_t_70]

[20190918171220989.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/18/e32868bfb2d940c29f14e912ccda4feb.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDc4NDY3Mw_size_16_color_FFFFFF_t_70]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/18/0e2538e4052d4d7b8449c50f64777642.png