mybatis的mapper.xml中resultMap标签的使用详解

谁践踏了优雅 2022-12-14 13:52 371阅读 0赞

> 在mybatis中有一个resultMap标签，它是为了映射select查询出来的结果的集合，其主要作用是将实体类中的字段与数据库表中的字段进行关联映射。当实体类中的字段与数据库表中的字段相同时，可以将resultMap标签中的关联关系忽略不写。当实体类中的字段与数据库表中的字段不相同时，就需要在resultMap标签中将实体类字段与数据库字段一一进行关联映射，或者开启驼峰规则，让它自动转换。
> 
> 使用resultMap，就要禁用驼峰规则。如果不想改实体类的话，可以采用resultMap。

<?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.example.page.mapper.UserMapper">
    
        <resultMap id="result" type="com.example.page.entity.User">
            <result property="userId" column="userId"/>
            <result property="userDate" column="userDate"/>
            <result property="userName" column="userName"/>
            <result property="userAddress" column="userAddress"/>
        </resultMap>
    
        <select id="ListUser" resultMap="result">
            select * from user
        </select>
    
    
        <select id="findUserByName" resultMap="result" parameterType="String">
            select * from user
            where userName like concat(concat('%',#{userName}),'%')
            order by userId desc
        </select>
    
        <select id="queryPage" resultMap="result" parameterType="Integer">
            select * from user
            order by userId desc
            limit #{startRows},5
        </select>
    
    
        <select id="getRowCount" resultType="Integer">
            select count(*) from user
        </select>
    
        <insert id="insertUser" parameterType="com.example.page.entity.User">
            insert into user
            (userId,userDate,userName,userAddress)
            values
            (#{userId},#{userDate},#{userName},#{userAddress})
        </insert>
    
        <delete id="delete" parameterType="int">
            delete from user where userId = #{userId}
        </delete>
    
        <update id="Update" parameterType="com.example.page.entity.User">
            update user
            set user.userDate=#{userDate},user.userName=#{userName},user.userAddress=#{userAddress}
            where user.userId=#{userId}
        </update>
    
    </mapper>

resultMap结果映射集用法详解：[https://blog.csdn.net/li\_w\_ch/article/details/109802957][https_blog.csdn.net_li_w_ch_article_details_109802957]

[https_blog.csdn.net_li_w_ch_article_details_109802957]: https://blog.csdn.net/li_w_ch/article/details/109802957