mybatis resultmap映射结果集（xml映射配置一）

自动映射例子

当数据库名称与pojo一致时候，可以直接自动映射

<select id="selectUsers" resultType="com.someapp.model.User"> select id, username, hashedPassword from some_table where id = #{id} </select>

当数据库名称与pojo不一致时候，采用类型别名，比如：

<select id="selectUsers" resultType="User"> select user_id as "id", user_name as "userName", hashed_password as "hashedPassword" from some_table where id = #{id} </select>

ResultMap设计

使用外部的 resultMap 会怎样，解决列名不匹配的另外一种方式。

数据库column -> java pojo property

<resultMap id="userResultMap" type="User"> <id property="id" column="user_id" /> <result property="username" column="user_name"/> <result property="password" column="hashed_password"/> </resultMap>

其中id表示主键,对应xml文件可配置如下

<select id="selectUsers" resultMap="userResultMap"> select user_id, user_name, hashed_password from some_table where id = #{id} </select>

ResultMap高级结果映射

pojo对象

public class Employee { private Integer id; private String realName; private SexEnum sex; private Date birthday; private String mobile; private String email; private String position; private String note; private WorkCard workCard; private List<EmployeeTask> employeeTasks; }

xml配置文件

<resultMap id="BaseResultMap" type="priv.dengjl.ns.bean.Employee"> <result column="id" jdbcType="INTEGER" property="id" /> <result column="real_name" jdbcType="VARCHAR" property="realName" /> <result column="sex" typeHandler="priv.dengjl.ns.handler.SexEnumHandler" property="sex" /> <result column="birthday" jdbcType="DATE" property="birthday" /> <result column="mobile" jdbcType="VARCHAR" property="mobile" /> <result column="email" jdbcType="VARCHAR" property="email" /> <result column="position" jdbcType="VARCHAR" property="position" /> <result column="note" jdbcType="VARCHAR" property="note" /> <association column="id" property="workCard" select="priv.dengjl.ns.mapper.WorkCardMapper.getWorkCardByEmpId" /> <collection column="id" property="employeeTasks" select="priv.dengjl.ns.mapper.EmployeeTaskMapper.getEmployeeTaskListByEmpId" /> <discriminator column="sex" javaType="int"> <case value="1" resultMap="MaleEmployeeMap"/> <case value="0" resultMap="FemaleEmployeeMap"/> </discriminator> </resultMap>

一对一 workCard对象

<association column="id" property="workCard" select="priv.dengjl.ns.mapper.WorkCardMapper.getWorkCardByEmpId" />

一对多 workCard对象

<association column="id" property="workCard" select="priv.dengjl.ns.mapper.WorkCardMapper.getWorkCardByEmpId" />

鉴别器

<discriminator column="sex" javaType="int"> <case value="1" resultMap="MaleEmployeeMap"/> <case value="0" resultMap="FemaleEmployeeMap"/> </discriminator>

其中select对应的值为单个文件的xml配置 1