mybatis入门（四）---ResultMap

michellc

　　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。