mybatis入门（三）---ResultMap

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　　下面将介绍一个resultMap最基本的用法-----一对一/has a 关系
　　 
　　承接上篇文章
　　 
　　1.新建表t_dept,并修改表t_user.建表语句如下

create table t_dept (deptno varchar2(11),deptname varchar2(22));
alter table t_dept add constraints pk_deptno primary key(deptno);
alter table t_user add(deptno varchar2(11));
insert into t_dept values('1111','dept1');
update t_user set deptno = '1111';
　　 2.添加实体类Dept.java

package com.mybatis.test.vo;
public class Dept {
private String deptNo;
private String deptName;
public Dept() {
super();
}
public String getDeptNo() {
return deptNo;
}
public void setDeptNo(String deptNo) {
this.deptNo = deptNo;
}
public String getDeptName() {
return deptName;
}
public void setDeptName(String deptName) {
this.deptName = deptName;
}
public String toString()
{
return " deptNo is: "+deptNo+" deptName is: "+deptName;
}
}
　　3.修改User.java
　　    在User类中添加对象Dept dept;
　　 4 修改User.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">
<mapper namespace="User">
<resultMap type="User" id="userResult">
<id property="id" column="user_id" />
<result property="userName" column="user_name" />
<association property="dept" column="user_dept_no"
javaType="Dept">
<id property="deptNo" column="dept_no" />
<result property="deptName" column="dept_name" />
</association>
</resultMap>
<select id="select1" parameterType="int" resultMap="userResult">
select u.id
as user_id,
u.username as user_name,
u.deptno as user_dept_no,
d.deptno
as dept_no,
d.deptname as dept_name
from t_user u,t_dept d
where u.deptno
= d.deptno
and u.id = #{id}
</select>
</mapper>
　　上述配置文件中resultMap中使用了<association>标签来实现关联。
　　5.在UserDAO类中加入以下方法：

public User getUserAndDept(int id)
{
SqlSession session = sqlSessionFactory.openSession();
try {
User user = (User) session.selectOne("User.select1", id);
return user;
} finally {
session.close();
}
}
　　6.在test中进行测试。