mybatis入门（四）---ResultMap

承接三，通过resultMap实现一对多。

1.在数据库中添加表t_pet,代码如下：

create table t_pet(id number(11), petname varchar2(11),userid number(11));
alter table t_pet add constraint pk_pet_id primary key(id);
update t_pet set userid = '4';

 2.在User类中加入对象List<Pet> pets;

 3.修改配置文件User.xml,在User.xml中加入如下内容：

<!-- 一对多关联 -->
	<resultMap type="User" id="userResult1">
		<id property="id" column="user_id" />
		<result property="userName" column="user_name" />
		<collection property="pets" ofType="Pet">
			<id property="id" column="pet_id" />
			<result property="petName" column="pet_name" />
			<result property="petColor" column="pet_color" />
		</collection>
	</resultMap>
	<select id="select2" parameterType="int" resultMap="userResult1">
		select u.id as user_id,
		u.username as user_name,
		p.userid as pet_user_id,
		p.id as pet_id,
		p.petname as pet_name,
		p.petcolor as pet_color
		from t_user u,t_pet p
		where u.id = p.userid
		and u.id = #{id}
   </select>

 上面<collection> 标签实现一对多的功能。

4.在Test中进行测试。