Mybatis 实体嵌套查询

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我是靠谱客的博主典雅橘子，这篇文章主要介绍Mybatis 实体嵌套查询，现在分享给大家，希望可以做个参考。

本例子只是一个实体类嵌套另外一个或者多个实体类。在实体类嵌套一个实体列表的我还没研究出来。

首先上实体类：

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public class AppPost {
    private String postId;
    private String postTitle;
    private int upTime;
    private int postType;
    private int pointsNum;
    private int collectionNum;
    private int replyNum;
    private int transferNum;
    private int isHost;
    private int contentType;
    private AppUserMini user;
}
 
 
public class AppUserMini {
    private String userId;
    private String userName;
    private Integer userSex;
    private Integer userAge;
    private String userImg;
    private String userAddress;
}

然后其他乱七八糟的就不说了，直接上xml的代码：

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<resultMap id="Base_app_post" type="com.openailab.oas.AppPost">
    <result column="post_id" property="postId"></result>
    <result column="post_title" property="postTitle"></result>
    <result column="up_time" property="upTime"></result>
    <result column="post_type" property="postType"></result>
    <result column="points_num" property="pointsNum"></result>
    <result column="collection_num" property="collectionNum"></result>
    <result column="reply_num" property="replyNum"></result>
    <result column="transfer_num" property="transferNum"></result>
    <result column="is_host" property="isHost"></result>
    <result column="content_type" property="contentType"></result>
    <association property="user" javaType="com.openailab.oas.AppUserMini" resultMap="Base_app_user"></association>
  </resultMap>
 
  <resultMap id="Base_app_user" type="com.openailab.oas.AppUserMini">
    <result column="user_id" property="userId"></result>
    <result column="user_name" property="userName"></result>
    <result column="user_sex" property="userSex"></result>
    <result column="user_age" property="userAge"></result>
    <result column="user_img" property="userImg"></result>
    <result column="user_address" property="userAddress"></result>
  </resultMap>
 
  <select id="selectAppByPostId" resultMap="Base_app_post" parameterType="java.lang.String">
    select a.post_id,a.post_title,a.up_time,a.post_type,a.points_num,
        a.collection_num,a.reply_num,a.transfer_num,a.is_hot,a.content_type,
        b.user_id,b.user_name,b.user_sex,b.user_age,b.user_img,b.user_address
    from service_post a,sys_user b
    where a.post_id = #{postId,jdbcType=INTEGER} AND a.user_id=b.user_id
  </select>

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<resultMap id="Base_app_post" type="com.openailab.oas.AppPost">
    <result column="post_id" property="postId"/>
    <result column="post_title" property="postTitle"/>
    <result column="up_time" property="upTime"/>
    <result column="post_type" property="postType"/>
    <result column="points_num" property="pointsNum"/>
    <result column="collection_num" property="collectionNum"/>
    <result column="reply_num" property="replyNum"/>
    <result column="transfer_num" property="transferNum"/>
    <result column="is_host" property="isHost"/>
    <result column="content_type" property="contentType"/>
    <association property="user" javaType="com.openailab.oas.AppUserMini" resultMap="Base_app_user"/>
  </resultMap>
 
  <resultMap id="Base_app_user" type="com.openailab.oas.AppUserMini">
    <result column="user_id" property="userId"/>
    <result column="user_name" property="userName"/>
    <result column="user_sex" property="userSex"/>
    <result column="user_age" property="userAge"/>
    <result column="user_img" property="userImg"/>
    <result column="user_address" property="userAddress"/>
  </resultMap>
 
  <select id="selectAppByPostId" resultMap="Base_app_post" parameterType="java.lang.String">
    select a.post_id,a.post_title,a.up_time,a.post_type,a.points_num,
        a.collection_num,a.reply_num,a.transfer_num,a.is_hot,a.content_type,
        b.user_id,b.user_name,b.user_sex,b.user_age,b.user_img,b.user_address
    from service_post a,sys_user b
    where a.post_id = #{postId,jdbcType=INTEGER} AND a.user_id=b.user_id
  </select>