MyBatis 多对多 查询

<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE mapper        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"        "http://mybatis.org/dtd/mybatis-3-mapper.dtd"><mapper namespace="cn.hello.dao.ITeacher">    <resultMap id="teacherMappers" type="Teacher">        <id column="tid" property="tid"></id>        <result column="tname" property="tname"></result>        <collection property="stus" ofType="Student">            <id column="sid" property="sid"></id>            <result column="sname" property="sname"></result>        </collection>    </resultMap><select id="getTeacher" resultMap="teacherMappers">    SELECT t.tid,t.tname,s.sid,s.sname  FROM teacher t,student  s ,teacher_student   ts  WHERE  t.tid=ts.tid  and  s.sid=ts.sid   and   t.tid=#{tid}</select></mapper>

@Test    public  void a(){        SqlSession session = MyBatisUtil01.getSession();        ICategory mapper = session.getMapper(ICategory.class);        List<Category> list = mapper.getChildreByPid(1);        for (Category item :list             ) {            System.out.println(item);        }    }