mybatis一对多查询

package com.springmvc.domain;

public class Student {
    private int id;
    private String studentname;
    private int tid;
    private int classid;


    public int getTid() {
        return tid;
    }

    public void setTid(int tid) {
        this.tid = tid;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }


    public String getStudentname() {
        return studentname;
    }

    public void setStudentname(String studentname) {
        this.studentname = studentname;
    }

    public int getClassid() {
        return classid;
    }

    public void setClassid(int classid) {
        this.classid = classid;
    }

    @Override
    public String toString() {
        return "Student{" +
                "id=" + id +
                ", studentname=‘" + studentname + ‘\‘‘ +
                ", tid=" + tid +
                ", classid=" + classid +
                ‘}‘;
    }
}

package com.springmvc.domain;

import java.util.List;

public class Teacher {
    private int id;
    private String name;
    private List<Student> list;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public List<Student> getList() {
        return list;
    }

    public void setList(List<Student> list) {
        this.list = list;
    }

    @Override
    public String toString() {
        return "Teacher{" +
                "id=" + id +
                ", name=‘" + name + ‘\‘‘ +
                ", list=" + list +
                ‘}‘;
    }
}

package com.springmvc.dao;

import com.springmvc.domain.Student;

import java.util.List;

public interface StudentMapper {
    /*List<Student> selectAll();*/
    List<Student> selectByTid(int id);
    /*List<Student> selectByCid(int cid);*/
}

package com.springmvc.dao;

import com.springmvc.domain.Teacher;

import java.util.List;

public interface TeacherMapper {
    /*Teacher selectAll(int id);*/

    List<Teacher> selAll();
    List<Teacher> selAll1();
}

 1 <?xml version="1.0" encoding="UTF-8" ?>
 2 <!DOCTYPE mapper
 3         PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
 4         "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
 5 <mapper namespace="com.springmvc.dao.TeacherMapper">
 6     <!--<select id="selectAll" resultType="com.springmvc.domain.Teacher">
 7         select * from teacher where id=#{0}
 8     </select>-->
 9 
10     <select id="selAll" resultMap="teachermap">
11         select * from teacher
12     </select>
13     //方式一
14     <resultMap id="teachermap" type="Teacher">
15        <id property="id" column="id"/>
16         <result property="name" column="name"/>
17         <collection property="list" ofType="Student" select="com.springmvc.dao.StudentMapper.selectByTid" column="id"/>
18     </resultMap>
19     
20     //方式二:使用左连接查询
21     <select id="selAll1" resultMap="teacher1">
22         select t.*,s.*
23         from teacher t left join student s on t.id = s.tid
24     </select>
25     
26     <resultMap id="teacher1" type="com.springmvc.domain.Teacher">
27         <id property="id" column="id"/>
28         <result property="name" column="name"/>
29         <collection property="list" ofType="com.springmvc.domain.Student">
30             <id property="id" column="id"/>
31             <result property="studentname" column="studentname"/>
32             <result property="tid" column="tid"/>
33             <result column="classid" property="classid"/>
34         </collection>
35     </resultMap>
36 
37 
38 
39 </mapper>

 1 <?xml version="1.0" encoding="UTF-8" ?>
 2 <!DOCTYPE mapper
 3         PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
 4         "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
 5 <mapper namespace="com.springmvc.dao.StudentMapper" >
 6   <!--  <select id="selectAll" resultMap="student">
 7         select * from student
 8     </select>-->
 9     <select id="selectByTid" resultType="Student">
10         select * from student where tid=#{0};
11     </select>
12 
13 
14   <!--  <resultMap id="student" type="com.springmvc.domain.Student">
15         <id property="id" column="_id"></id>
16         <result property="studentName" column="student_name"></result>
17         <result property="tid" column="t_id"/>
18         <association property="teacher" select="com.springmvc.dao.TeacherMapper.selectAll" column="t_id"></association>
19     </resultMap>-->
20 
21 
22 
23 
24 </mapper>