db.driver=com.mysql.jdbc.Driver

db.url=jdbc:mysql://localhost:3306/demo?useUnicode=true&characterEncoding=utf8

db.username=root

db.password=123456

 <?xml version="1.0" encoding="UTF-8" ?>

 <!DOCTYPE configuration

 PUBLIC "-//mybatis.org//DTD Config 3.0//EN"

 "http://mybatis.org/dtd/mybatis-3-config.dtd">

 <configuration>

     <!-- 加载java的配置文件 -->

     <properties resource="config/db.properties"/>

     <!-- 配置mybatis的环境信息，与spring整合，该信息由spring来管理 -->

     <environments default="development">

         <environment id="development">

             <!-- 配置JDBC事务控制，由mybatis进行管理 -->

             <transactionManager type="JDBC"></transactionManager>

             <!-- 配置数据源，采用mybatis连接池 -->

             <dataSource type="POOLED">

                 <property name="driver" value="${db.driver}" />

                 <property name="url" value="${db.url}" />

                 <property name="username" value="${db.username}" />

                 <property name="password" value="${db.password}" />

             </dataSource>

         </environment>

     </environments>

     <!-- 加载映射文件 -->

     <mappers>

         <mapper resource="config/mapper.xml" />

     </mappers>

 </configuration>

 <?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="com.xiaostudy.domain.Mapper">

     <!-- ========================================================================================== -->

     <!-- 一对多之resultMap1 -->

     <select id="findOfTeacher" resultMap="OfTeacher">

         select * from  teacher t, student s where t.tid=s.tid and t.tid=#{id}

     </select>

     <resultMap type="com.xiaostudy.domain.Teacher" id="OfTeacher">

         <id column="tid" property="tid"/>

         <result column="tname" property="tname"/>

         <collection  property="student" ofType="com.xiaostudy.domain.Student" ><!-- javaType="HashSet" -->

             <id column="sid" property="sid"></id>

             <result column="tid" property="tid"/>

             <result column="sname" property="sname"/>

         </collection>

     </resultMap>

    <!-- ========================================================================================== -->

     <!-- ========================================================================================== -->

     <!-- 一对多之resultMap2 -->

     <select id="findOfTeachers" resultMap="OfTeachers">

         select * from teacher t, student s  where t.tid=s.tid and t.tid=#{id}

     </select>

     <resultMap type="com.xiaostudy.domain.Teacher" id="OfTeachers">

         <id column="tid" property="tid"/>

         <result column="tname" property="tname"/>

         <collection property="student" ofType="com.xiaostudy.domain.Student" select="getStudent" column="tid"/>

     </resultMap>

     <select id="getStudent" parameterType="int" resultType="com.xiaostudy.domain.Student">

         select * from student s where s.tid = #{id}

     </select>

    <!-- ========================================================================================== -->

 </mapper>

 package com.xiaostudy.domain;

 public class Student {

     private int sid;

     private int tid;

     private String sname;

     private Teacher teacher;

     public int getSid() {

         return sid;

     }

     public void setSid(int sid) {

         this.sid = sid;

     }

     public int getTid() {

         return tid;

     }

     public void setTid(int tid) {

         this.tid = tid;

     }

     public String getSname() {

         return sname;

     }

     public void setSname(String sname) {

         this.sname = sname;

     }

     public Teacher getTeacher() {

         return teacher;

     }

     public void setTeacher(Teacher teacher) {

         this.teacher = teacher;

     }

     @Override

     public String toString() {

         return "Student [sid=" + sid + ", tid=" + tid + ", sname=" + sname

                 + ", teacher=" + teacher + "]";

     }

 }

 package com.xiaostudy.domain;

 import java.util.Set;

 public class Teacher {

     private int tid;

     private String tname;

     private Set<Student> student;

     public Set<Student> getStudent() {

         return student;

     }

     public void setStudent(Set<Student> student) {

         this.student = student;

     }

     public int getTid() {

         return tid;

     }

     public void setTid(int tid) {

         this.tid = tid;

     }

     public String getTname() {

         return tname;

     }

     public void setTname(String tname) {

         this.tname = tname;

     }

     @Override

     public String toString() {

         return "Teacher [tid=" + tid + ", tname=" + tname + ", student=" + student + "]";

     }

 }

 package com.xiaostudy.domain;

 import java.util.List;

 public interface Mapper {

     // 一对多之resultMap1

     public List<Teacher> findOfTeacher(int id);

     // 一对多之resultMap2

     public List<Teacher> findOfTeachers(int id);

 }

 package com.xiaostudy.test;

 import java.io.IOException;

 import java.io.InputStream;

 import java.util.List;

 import org.apache.ibatis.io.Resources;

 import org.apache.ibatis.session.SqlSession;

 import org.apache.ibatis.session.SqlSessionFactory;

 import org.apache.ibatis.session.SqlSessionFactoryBuilder;

 import com.xiaostudy.domain.Mapper;

 import com.xiaostudy.domain.Teacher;

 /**

  * @desc 测试类

  * @author xiaostudy

  *

  */

 public class MybatisTest {

     public static void main(String[] args) throws IOException {

         String resource = "config/SqlMapConfig.xml";

         InputStream inputStream = Resources.getResourceAsStream(resource);

         // 创建SqlSessionFactory

         SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

         // 创建SqlSession

         SqlSession sqlSession = sqlSessionFactory.openSession();

         // 获取一个代理dao实现

         Mapper mapper = sqlSession.getMapper(Mapper.class);

         //一对多之resultMap1

         /*List<Teacher> list = mapper.findOfTeacher(1);

         for(Teacher t : list) {

             System.out.println(t);

         }*/

         //一对多之resultMap2

         List<Teacher> list = mapper.findOfTeachers(1);

         for(Teacher t : list) {

             System.out.println(t);

         }

         sqlSession.close();

     }

 }