MyBatis之映射文件——MyBatis框架一对一与一对多

1.新建MyBatis项目                                           

                 

   2.新建数据库表单 

                                     

 

3. 一对多：一个用户有多个地址

property：addressList为UserInfo类成员变量

ofType：集合元素数据类型

	<resultMap type="com.jd.vo.UserInfo" id="ui">
		<id column="ui_id" property="id"/>
		<result column="user_name" property="userName"/>
		<result column="password" property="password"/>
		<result column="ui_real_name" property="realName"/>
		<result column="age" property="age"/>
		
		<collection property="list" ofType="com.jd.vo.Address">
			<id  column="address_id" property="id"/>
			<result column="addr_real_name" property="realName"/>
			<result column="mobile" property="mobile"/>
			<result column="address" property="address"/>
		</collection>
	</resultMap>
	
	<select id="get" resultMap="ui">
		select 
		ui.id ui_id,user_name,password,ui.real_name ui_real_name,age,
		addr.id address_id,addr.real_name addr_real_name,mobile,address 
		from user_info ui
		LEFT JOIN address addr on addr.user_id=ui.id
		where ui.id=#{id}
	</select>

4.一对一：一个用户只有一个地址

property标签属性值为UserInfo Address类型属性名；

javaType:指定address属性数据类型[不能省略]

	<resultMap type="com.jd.vo.UserInfo" id="ui">
		<id column="ui_id" property="id"/>
		<result column="user_name" property="userName"/>
		<result column="password" property="password"/>
		<result column="ui_real_name" property="realName"/>
		<result column="age" property="age"/>
		<association property="address" javaType="com.jd.vo.Address">
			<id  column="address_id" property="id"/>
			<result column="addr_real_name" property="realName"/>
			<result column="mobile" property="mobile"/>
			<result column="address" property="address"/>
		</association>
	</resultMap>