使用配置

spring:datasource:url: jdbc:mysql://127.0.0.1:3306/test?useUnicode=true&characterEncoding=UTF8&zeroDateTimeBehavior=convertToNull&serverTimezone=Asia/Shanghai&rewriteBatchedStatements=truedriver-class-name: com.mysql.cj.jdbc.Driverusername: rootpassword: 123456
# xml路径
mybatis:mapper-locations: classpath:mapper/*.xml
#日志
logging:level:com.example.demo.dao: DEBUG

@MapperScan("com.example.demo.dao")//扫描指定包下接口

使用细节

一对一

<resultMap id="map" type="com.example.demo.entity.PlayTotal"><id column="id" jdbcType="INTEGER" property="id" /><result column="name" jdbcType="VARCHAR" property="name" /><!--1.直接手写--><association property="studentList" javaType="com.example.demo.entity.Student"><id column="b_id" jdbcType="INTEGER" property="id" /><result column="b_name" jdbcType="VARCHAR" property="name" /><result column="b_user_id" jdbcType="INTEGER" property="userId" /></association><!--2.前缀手写--><association property="studentList" columnPrefix="b_" javaType="com.example.demo.entity.Student"><id column="id" jdbcType="INTEGER" property="id" /><result column="name" jdbcType="VARCHAR" property="name" /><result column="user_id" jdbcType="INTEGER" property="userId" /></association><!--3.前缀并且其他地方引入--><association property="studentList" columnPrefix="b_" resultMap="com.example.demo.dao.StudentBaseDao.BaseResultMap"></association>
</resultMap><select id="select" resultMap="map">select a.id, a.name,b.id as b_id, b.name as b_name,b.user_id as b_user_idfrom play ainner join student bon a.id = b.user_id
</select>

一对多（基本数据类型）

<resultMap id="map" type="com.example.demo.entity.PlayTotal"><id column="id" jdbcType="INTEGER" property="id" /><result column="name" jdbcType="VARCHAR" property="name" /><collection property="studentList" ofType="java.lang.String"><constructor><arg column="b_name"/></constructor></collection></resultMap><select id="select" resultMap="map">select a.id, a.name,b.name as b_namefrom play aleft join student bon a.id = b.user_id</select>

一对多

  <resultMap id="map" type="com.example.demo.entity.PlayTotal"><id column="id" jdbcType="INTEGER" property="id" /><result column="name" jdbcType="VARCHAR" property="name" /><!--2.前缀手写--><collection property="studentList" columnPrefix="b_" ofType="com.example.demo.entity.Student"><id column="id" jdbcType="INTEGER" property="id" /><result column="name" jdbcType="VARCHAR" property="name" /><result column="user_id" jdbcType="INTEGER" property="userId" /></collection><!--3.前缀其他地方引入--><collection property="studentList" columnPrefix="b_" resultMap="com.example.demo.dao.StudentBaseDao.BaseResultMap"></collection></resultMap><select id="select" resultMap="map">select a.id, a.name,b.id as b_id, b.name as b_name,b.user_id as b_user_idfrom play aleft join student bon a.id = b.user_id</select>