1、实现效果

2、Mapper配置文件

<mapper namespace="com.baizhi.dao.TeacherDao">
	<resultMap type="teacher" id="teacherMap">
        <id column="teaId" property="teacherId"/>
        <result column="teaName" property="teacherName"/>
        <association property="academy" javaType="academy"> 
            <id column="academy_id" property="academyId"/>
            <result column="acaName" property="academyName"/>
        </association>
        <collection ofType="course" property="courses">
            <id column="course_id" property="courseId"/>
            <result column="couName" property="courseName"/>
        </collection>
    </resultMap>  
	<select id="selectAllTeachers" resultMap="teacherMap">
	    select tea.teacher_id as teaId,tea.teacher_name as teaName,
        aca.academy_name as acaName,cou.course_name as couName
        from interact_teacher tea left join interact_academy aca        
        on tea.academy_id=aca.academy_id
        left join interact_course cou 
        on cou.teacher_id=tea.teacher_id order by tea.teacher_id
	</select>	
</mapper>

3、页面展示

<c:forEach items="${teachers}" var="teacher">
   <tr>
      <th style="text-align: center;">${teacher.teacherId }</th>
          <th style="text-align: center;">${teacher.teacherName }</th>
          <th style="text-align: center;">${teacher.academy.academyName }
      <th style="text-align: center;">
          <c:forEach items="${teacher.courses}" var="course" varStatus="status">
	      <span>${course.courseName}
		  <c:if test="${!status.last}">,</c:if>
	      </span>		                  
           </c:forEach>
       </th>
    </tr>
</c:forEach>