MyBatis对多关系：显示该用户的所有角色

只要在一边的UserMapper.xml 配置好就可以了

 <?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">

 <!--需求:搜索该用户的所有角色和该用户的信息-->
 <mapper namespace="mybatis.UserMapper">
 <!--为返回的结果集和pojo属性,做对应关系    -->
 <!--MyBatis中与hibernate不同的orm的地方，mybatis是返回的结果集映射到pojo中的属性，而不是在建立表的时候映射-->
     <resultMap type="com.free.mybatis.domain.User" id="qwe">
 <!--所以他需要column来定位具体的属性    -->
         <id property="uid" column="UID"/>
         <result property="user_name" column="USER_NAME"/>
　　　　　　　　　<!--下面是根据sql返回的结果集依次设置到pojo，不写则无值-->
 <!--        <result property="user_password" column="USER_PASSWORD"/>-->
 <!--        <result property="user_desc" column="USER_DESC"/>-->
 <!--        <result property="e_mail" column="E_MAIL"/>-->
 <!--        <result property="phone" column="PHONE"/>-->
 <!--    配置关联(应该采用extends的方式)    -->

     </resultMap>

     <resultMap type="com.free.mybatis.domain.User" id="rolemapper" extends="qwe">
 <!--对多关系 collection    -->
 <!--对一关系 association-->
         <collection property="roles" ofType="com.free.mybatis.domain.Role">
             <id property="rid" column="RID"/>
             <result property="name" column="NAME"/>
             <result property="pid" column="PID"/>
             <result property="isParent" column="ISPARENT"/>
             <result property="checked" column="CHECKED"/>
         </collection>
     </resultMap>

     <select id="findUserRole" parameterType="map" resultMap="rolemapper">
         SELECT u.*,r.*
         FROM USER u
         LEFT JOIN user_role ur
         ON u.uid = ur.uid
         LEFT JOIN role r
         ON ur.rid = r.rid
         <where>
         <if test="username!=null">u.user_name=#{username}</if>
         </where>
     </select>
 </mapper>

package com.free.mybatis.test;

import java.io.IOException;
import java.io.InputStream;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

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 org.junit.Test;

import com.free.mybatis.domain.Role;
import com.free.mybatis.domain.User;
@SuppressWarnings(value = { "unused" })
public class testDemo1 {
    @Test
    public void test1() throws IOException {
        String resource="sqlMapConfig.xml";
//        InputStream is = testDemo1.class.getClassLoader().getResourceAsStream(resource);
//        resource.get
        InputStream is = Resources.getResourceAsStream(resource);
        SqlSessionFactory sfb = new SqlSessionFactoryBuilder().build(is);
        SqlSession sqlSession = sfb.openSession();
        Map<String,Object> map = new HashMap<String,Object>();
//        map.put("username", "')
//        new HashMap<>();
//        map.put("username", "freedom");
        List<User> list = sqlSession.selectList("mybatis.UserMapper.findUserRole", map);
            for(User user : list) {
//                System.out.println(user.getRoles());
                System.out.println(user.toString());
//                for(Role roles :user.getRoles())
//                    System.out.println(user.getUser_name()+":"+roles.getName());
            }
//        sqlSession.commit();
//        System.out.println(list);
    }
}

<?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>
<!--datasource和transaction    -->
<!--test/development-->
    <environments default="test">
<!--可以有多个环境，测试和部署    -->
        <environment id="test" >
<!-- 事务：JDBC/MANAGED jdbc默认事务部自动提交-->
            <transactionManager type="JDBC">
            </transactionManager>
                <!-- 数据源：POOLED/UNPOOLED/JNDI -->
            <dataSource type="POOLED">
             <property name="driver" value="com.mysql.jdbc.Driver" />
            <property name="url" value="jdbc:mysql://localhost:3306/gyl" />
            <property name="username" value="root" />
            <property name="password" value="freedom2012" />
            </dataSource>
        </environment>

            <environment id="test" >
<!-- 事务：JDBC/MANAGED jdbc默认事务部自动提交-->
            <transactionManager type="JDBC">
            </transactionManager>
                <!-- 数据源：POOLED/UNPOOLED/JNDI -->
            <dataSource type="POOLED">
             <property name="driver" value="com.mysql.jdbc.Driver" />
            <property name="url" value="jdbc:mysql://localhost:3306/gyl" />
            <property name="username" value="root" />
            <property name="password" value="freedom2012" />
            </dataSource>
        </environment>
    </environments>

    <mappers>
<!--加载domain的映射    -->
        <mapper resource="mybatis/UserMapper.xml"/>
    </mappers>
</configuration>