作者：fyupeng
技术专栏：☞ https://github.com/fyupeng
项目地址：☞ https://github.com/fyupeng/distributed-blog-system-api

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留给读者

一、介绍

比如你需要在Company对象中，嵌套列表SonCompanys和ContactInfos，而且还是直接通过数据库查询出来，不想自己遍历去构造这种对象，那么你可以使用MyBatis的collection 关键字。

二、代码

<select id="queryCompanyDataByKey" resultMap="CompanyItemMap">select * from (select a.id, a.area, a.uniscid, a.updatetime as updateTime, b.area as sonArea, b.uniscid as sonUniscid, c.name as contactNamefrom company a inner join son_comopany b on a.sonId = b.idinner join contact_info c on a.contact_id = c.id)
</select>

<resultMap id="CompanyItemMap" type="com.fyupeng.company"><id property="id" column="id" /><result property="area" column="area" /><result property="uniscid" column="uniscid" />// 子公司<result property="updateTime" column="updateTime" /><collection property="sonCompanys" ofType="com.fyupeng.SonCompany"><result property="sonArea" column="sonArea" /><result property="sonUniscid" column="sonUniscid" /></collection>// 联系人信息<collection property="contactInfos" ofType="com.fyupeng.ContactInfo"><result property="contactName" column="contactName" /></collection></resultMap>

三、总结

简洁、高效、实用！