[Java] PageHelper插件实现一对多查询时的分页问题

<resultmap id="basemap" type="com.xx.oo.activity">
  <id column="id" property="id" jdbctype="integer"/>
  ....
</resultmap>
 
<resultmap id="resultmap" type="com.xx.oo.activity" extends="basemap">
  <collection property="templates" oftype="com.xx.oo.template">
  <id column="pt_id" property="id" jdbctype="integer"/>
  <result column="pt_title" property="title" jdbctype="varchar"/>
  </collection>
</resultmap>
 
<resultmap id="richresultmap" type="com.xx.oo.activity" extends="basemap">
  <!--property：对应javabean中的字段-->
  <!--oftype：对应javabean的类型-->
  <!--javatype：对应返回值的类型-->
  <!--column：对应数据库column的字段，不是javabean中的字段-->
  <!--select：对应查询子集的sql-->
  <collection property="templates" oftype="com.xx.oo.template" javatype="java.util.list" column="id" select="querytemplatebyid">
  <id column="pt_id" property="id" jdbctype="integer"/>
  <result column="pt_title" property="title" jdbctype="varchar"/>
  </collection>
</resultmap>
 
<resultmap id="template" type="com.xx.oo.template">
  <id column="pt_id" property="id" jdbctype="integer"/>
  <result column="pt_title" property="title" jdbctype="varchar"/>
</resultmap>

<!--这里的#{id}参数就是collection中定义的column字段-->
<select id="querytemplatebyid" parametertype="java.lang.integer" resultmap="template">
  select id pt_id, title pt_title
  from t_activity_template where is_delete=0 and activity_id = #{id}
  order by sort_number desc
</select>
<select id="querybypage" parametertype="com.xx.oo.activitypagerequest" resultmap="richresultmap">
  select t.*,t1.real_name creator_name
  from t_activity t
  left join user t1 on t1.user_id = t.creator
  <where>
  t.is_delete = 0
  <if test="criteria != null and criteria.length()>0">and (t.activity_name like concat("%",#{criteria},"%"))</if>
  </where>
  order by t.id desc
</select>

<select id="querybyid" parametertype="java.lang.integer" resultmap="resultmap">
  select t.*, t6.id pt_id, t1.title pt_title
  from t_activity t
  left join t_activity_template t1 on t.id=t6.activity_id and t1.is_delete=0
  where t.is_delete = 0 and t.id = #{id}
</select>