mybatis 得到多級用collection 放孩子節點

<resultMap id="BaseResultMap2" type="com.pojo.CaCategoryTreeVo">
        <id column="id" jdbcType="INTEGER" property="id"/>
        <result column="title" jdbcType="VARCHAR" property="title"/>
        <result column="parentid" jdbcType="INTEGER" property="parentId"/>
        <collection property="children" select="getMenus" column="id" ofType="com.pojo.CaCategoryTreeVo"
                    javaType="java.util.ArrayList">
        </collection>
    </resultMap>


    <select id="getMenus" resultMap="BaseResultMap2" parameterType="java.lang.Integer">
SELECT
   id ,title,parentid
FROM
   ca_category
WHERE
  category_type=1
   and parentid=#{_parameter}
    </select>

    <select id="selectTree" resultMap="BaseResultMap2" parameterType="java.lang.Integer">
<if test="id !=null ">
    SELECT
    id ,title,parentid
    FROM
    ca_category
    WHERE
    category_type =1
    and id = #{id}

</if>
        <if test="id ==null  ">
            SELECT
            id ,title,parentid
            FROM
            ca_category
            WHERE
            category_type = 1
            AND parentid in (
            SELECT
            id
            FROM
            ca_category
            WHERE
            category_type = 1
            AND parentid = 0
            )
        </if>
    </select>