MyBitis(iBitis)系列随笔之五：多表(一对多关联查询)

MyBitis(iBitis)系列随笔之一：MyBitis入门实例

这篇博文介绍的是多表中的一对多表关联查询
还是按照上一篇的步骤，先做一些准备工作；创建两张表：一张是用户，一张是用户所对应的移动手机，一户用户可以有部移动手机。
这是用户t_user表

        这是移动电话t_mobile表

           在Java实体对象对中，一对多可以根据List和Set来实现，两者在mybitis中都是通过collection标签来配合使用，稍后会做详细配置介绍

创建表对应的JavaBean对象

Mobile Bean

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public class Mobile {
private int id;
private String telnumber;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getTelnumber() {
return telnumber;
}
public void setTelnumber(String telnumber) {
this.telnumber = telnumber;
}
}

User Bean

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package com.jefry;
import java.util.List;
public class User {
private int id;
private String userName;
private String password;
private List<Mobile> mobiles; //这里也可以是Set集合
public List<Mobile> getMobiles() {
return mobiles;
}
public void setMobiles(List<Mobile> mobiles) {
this.mobiles = mobiles;
}
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
}

在上一篇的基础上改写映射文件：

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<?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="user">
<resultMap id="userResultMap" type="User">
<id property="id" column="id" javaType="int" jdbcType="INTEGER" />
<result property="userName" column="name" javaType="string" jdbcType="VARCHAR"/>
<result property="password" column="pass" javaType="string" jdbcType="VARCHAR"/>
<collection property="mobiles" column="userid" ofType="Mobile">
<id property="id" column="id" javaType="int" jdbcType="INTEGER"/>
<result property="telnumber" column="telnumber" javaType="string" jdbcType="VARCHAR"/>
</collection>
</resultMap>
<select id="selectUser" parameterType="int" resultMap="userResultMap" >
select m.id m_id,m.telnumber,u.id u_id,u.name,u.pass from t_mobile m,t_user u where m.userid = u.id and u.id = #{id}
</select>
</mapper>

最后，通过测试OK

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public class Test {
static String resource = "mybatis-config.xml";
public static void main(String[] args) throws IOException {
InputStream inputStream = Resources.getResourceAsStream(resource);
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
SqlSession session = sqlSessionFactory.openSession();
try {
User user = session.selectOne("user.selectUser", 1);
List<Mobile> mobiles = user.getMobiles();
for(Mobile mobile : mobiles) {
System.out.println("user:" + user.getUserName() + ",tel:" + mobile.getTelnumber());
}
} finally {
session.close();
}
}
}

源码下载：http://download.csdn.net/detail/jefry_xdz/5229451

http://blog.csdn.net/jefry_xdz/article/details/8767358

http://www.cnblogs.com/yinkh/p/5564033.html