1、Peson.java简述：（省略getter setter方法）
public class Person {
private PersonInfo personInfo; //对一关联person 对一关联personInfo,
private Integer id;
private String name;
private Integer age;
private String remark;
...
}
2、PersonInfo.java简述(省略setter getter)
public class PersonInfo {
private Integer id;
private String station;
private Date joinDate;
...
}
3、映射文件personInfoMapper.xml
<?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">
<!-- 配置命名空间，区别名称 -->
<mapper namespace="cn.itcast.mapper.PersonInfoMapper">
<!-- 中间，对象的属性和结果集的字段之间的对应关系 -->
<resultMap type="cn.itcast.domain.Person" id="personInfoRM">
<!-- 主键映射 -->
<id property="id" column="ID"/>
<!-- 普通字段 property指实体的属性；column结果集的字段名称 -->
<result property="name" column="USERNAME"/>
<result property="age" column="AGE"/>
<result property="remark" column="REMARK"/>
</resultMap>
<!-- 对象关联 -->
<!-- (1)使用继承方式，通过association标签配置对一关联关系 -->
<resultMap type="cn.itcast.domain.Person" id="personPersonInfoRM" extends="personInfoRM">
<association property="personInfo" javaType="cn.itcast.domain.PersonInfo">
<id property="id" column="INFOID"/>
<result property="station" column="STATION"/>
<result property="joinDate" column="JOIN_DATE"/>
</association>
</resultMap>
<!-- 查询，人员和人员扩展信息 -->
<select id="findPersonInfo" parameterType="map" resultMap="personPersonInfoRM">
<!--左外链接查询-->
SELECT
person.*,person_info.id AS infoid,person_info.join_date,person_info.station
FROM
person LEFT JOIN person_info ON person.id=person_info.id
<where>
<if test="name!=null">username=#{name}</if>
</where>
</select>
</mapper>
4、测试方法testFindPersonInfo.java
package test;
import java.io.IOException;
import java.io.InputStream;
import java.io.Reader;
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.Before;
import org.junit.Test;
import cn.itcast.domain.Person;
public class PersonInfoTest {
private SqlSessionFactory sqlSessionFactory;
//获取sqlSession
@Before
public void get() throws IOException{
String resource = "sqlMapConfig.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
}
/**
* 根据Person与PersonInfo之间的对一映射查询person信息
*/
@Test
public void testFindPersonInfo(){
SqlSession session = sqlSessionFactory.openSession();
//如何访问mapper中的方法呢？ 规则：命名空间+.+id
Map map = new HashMap();
List<Person> persons = session.selectList("cn.itcast.mapper.PersonInfoMapper.findPersonInfo", map);
for (Person person : persons) {
System.out.println(person);
}
}
}
<--------------------------------新手上路，有错误地方还望指正----------------------->
本文出自 “12285883” 博客，请务必保留此出处http://12295883.blog.51cto.com/12285883/1893253
原文：http://12295883.blog.51cto.com/12285883/1893253