mybatis入门（三）---ResultMap

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。