public class Student implements Serializable {
    private int id;
    private String stuNum;  //學(xué)號(hào)
    private String password;
    private String stuName;
    private String grade;   //年級(jí)
    private String department;  //系
    private String professional;    //專業(yè)
    private List<Subject> subList; //修讀課程
}

public class Subject implements Serializable {
    private Integer id;
    private String subjectName;
    }

<resultMap id="Map_stu_sub" type="student">
        <id column="id" property="id"></id>
        <result column="stuNum" property="stuNum"></result>
        <result column="stuName" property="stuName"></result>
        <result column="grade" property="grade"></result>
        <result column="department" property="department"></result>
        <result column="professional" property="professional"></result>
        <collection property="subList" ofType="subject">
            <!--將subject的id改成其他別名，不然會(huì)跟student的id字段沖突-->
            <id column="sub_id" property="id"></id>
            <result column="subjectName" property="subjectName"></result>
        </collection>
    </resultMap>

    <select id="stu_sub" resultMap="Map_stu_sub">
       SELECT a.*,c.id as sub_id,c.subjectName FROM student a LEFT OUTER JOIN stu_sub b ON a.id=b.stuId LEFT JOIN SUBJECT c ON b.subId=c.id WHERE a.id = #{id}
    </select>