resultMap

• 自定义某个javaBean的封装规则
  • type：自定义规则的Java类型
  • id：唯一id方便引用
• 指定主键列的封装规则
  • id：定义主键底层会有优化
  • column：指定哪一列
  • property：指定对应的javaBean属性

public interface EmployeeMapperPlus {public Employee getEmpById(Integer id);}

<?xml version="1.0" encoding="UTF-8" ?><!DOCTYPE mapperPUBLIC "-//mybatis.org//DTD Mapper 3.0//EN""http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.atguigu.mybatis.dao.EmployeeMapperPlus"><resultMap id="MyEmp" type="com.atguigu.mybatis.bean.Employee"><!--        指定主键列的封装规则column:指定哪一列property:指定对应的javaBean属性--><!--id定义主键底层会有优化--><id column="id" property="id"></id><!--        定义普通列封装规则--><result column="last_name" property="lastName"></result><!--        其他不指定的列会自动封装,我们只要写resultMap就把全部的映射规则都写上--><result column="email" property="email"></result><result column="gender" property="gender"></result></resultMap><!--    resultMap:自定义结果集映射规矩--><!--    public Employee getEmpById(Integer id);--><select id = "getEmpById" resultMap="MyEmp">select * from tb1_employee where id = #{id}</select></mapper>

    @Testpublic void test03() throws IOException {SqlSessionFactory sqlSessionFactory = getSqlSessionFactory();SqlSession sqlSession = sqlSessionFactory.openSession();try{EmployeeMapperPlus mapper = sqlSession.getMapper(EmployeeMapperPlus.class);Employee map = mapper.getEmpById(1);System.out.println(map);}finally {sqlSession.close();}}