Mybatis结果集映射

一、使用场景

当数据库里的列名和实体类的属性名不一致，就需要进行结果映射
在这里插入图片描述

二、UserMapper接口

package com.william.dao;import com.william.domain.QueryValueObject;
import com.william.domain.User;
import org.apache.ibatis.annotations.Param;import java.util.HashMap;
import java.util.List;public interface UserMapper {/*** 结果映射* @param username* @param sex* @param startIndex* @param pageSize* @return*/public List<User>   findByManyConditionByParamByResultMap(@Param("username") String username, @Param("sex") String sex, @Param("startIndex")Integer startIndex,@Param("pageSize") Integer pageSize);
}

三、UserMapper.xml

<?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.william.dao.UserMapper"><!--结果映射--><!--id :唯一标识type:返回值类型--><resultMap id="userMap" type="user"><!--映射主键column:列名property:属性名--><id column="id" property="id"></id><result column="_username" property="username"></result></resultMap><select id="findByManyConditionByParamByResultMap" resultMap="userMap">select * from user where _username like "%"#{username}"%" and sex=#{sex}limit #{startIndex},#{pageSize}</select>
</mapper>

四、TestCrud测试类

package com.william;import com.william.dao.UserMapper;
import com.william.domain.QueryValueObject;
import com.william.domain.User;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Test;import javax.annotation.Resource;
import java.io.IOException;
import java.io.InputStream;
import java.util.HashMap;
import java.util.List;/*** @author ：lijunxuan* @date ：Created in 2019/7/12  10:16* @description ：* @version: 1.0*/
public class TestCrud {/*** 结果映射   Mybatis多条件直接查询Param注解版* @throws IOException*/@Testpublic void findByManyConditionByParamByResultMap() throws IOException {InputStream inputStream = Resources.getResourceAsStream("Mybatis-configuration.xml");SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);SqlSession sqlSession = sqlSessionFactory.openSession();//获取某接口的动态代理对象（获取某接口的一个实现类）UserMapper userMapper = sqlSession.getMapper(UserMapper.class);QueryValueObject queryValueObject = new QueryValueObject();List<User> userMapperByConditionByMap = userMapper.findByManyConditionByParamByResultMap("a","男",0,7);for (User user1 : userMapperByConditionByMap) {System.out.println(user1);}sqlSession.close();}
}