MyBatis处理多对一关联对象映射的两种方法

1、举例说明：多个demo对应demo1实体对象；package com.liwei.shiro.model;public class Demo { private String name; private Integer age; private String password; private Demo1 d1;省略set，get方法 } }

2、创建demo1对象；public class Demo1 { private String name; public void setName(String name) { this.name = name; } public String getName() { return name; }}

3、创建demo的dao层，创建service。此处省略。配置dao的代理对象mapper文竭惮蚕斗件。<resultMaptype="cn.itcast.domain.Demo"id="ordersUserResultMap"><idcolumn="id"property="id"/><resultcolumn="name"property="name"/><resultcolumn="age'"property="age"/><resultcolumn="password"property="password"/>

4、<associationproperty="demo1"javaType="cn.itcast.domain.Demo1"><idcolumn="id"property="id"/><resultcolumn="name"property="name"/> </association></resultMap>

5、此处resultMap对应id，<selectid="findOrdersUserResultMap"resultMap="ordersUserResultMap"> select * fromdemo d,demo1 d1 where demo.id = demo1.id</select>

6、方法二直接返回map集合，<selectid=争犸禀淫"findOrdersUserResultMap"resultMap="ordersUser伊怕锱鳏ResultMap"> selectd.id as id,a.name as name,d.age as age,d.password as word ,d1.name as name1 fromdemo d,demo1 d1 where demo.id = demo1.id</select>

7、此方法直接将两个对象的属性直接封装在map集合里面，用的时候直接去，相当于在entity层创建dto层；当然，也可以在entity创建dto层，返回dto实体对象；