mybatis一对多两种mapper写法实例

mybatis一对多两种mapper写法

第一种

<resultMap type="com.example.demo.model.TuserModel" id="extendMapper">
 <id column="id" property="id" />
 <result column="user_name" property="userName" />
 <result column="nick_name" property="nickName" />
 <result column="avatar" property="avatar" />
 <result column="email" property="email" />
 <result column="signature" property="signature" />
 <result column="create_time" property="createTime" />
 <result column="update_time" property="updateTime" />
 <result column="del_flag" property="delFlag" />
 <collection property="tpluginModels" ofType="com.example.demo.model.TpluginModel"
 column="id">
 <id column="pid" property="id" />
 <result column="user_id" property="userId" />
 <result column="name" property="name" />
 <result column="icon" property="icon" />
 <result column="vsersion" property="vsersion" />
 <result column="tags" property="tags" />
 <result column="description" property="description" />
 <result column="bcreate_time" property="createTime" />
 <result column="bupdate_time" property="updateTime" />
 <result column="del_flag" property="delFlag" />
 </collection>
 </resultMap>

sql语句用联表查询

 u.*,p.id
 as
 pid,p.user_id,p.name,p.icon,p.vsersion,p.tags,p.description,p.create_time
 as bcreate_time,p.update_time as bupdate_time,p.del_flag from t_user u
 LEFT
 JOIN t_plugin p ON u.id=p.user_id and u.del_flag=0 and
 p.del_flag=0 WHERE
 u.user_name LIKE CONCAT('%',#{name},'%') OR
 u.nick_name LIKE
 CONCAT('%',#{name},'%')

第二种

<resultMap type="com.example.demo.model.TuserModel" id="extendMapper">
 <id column="id" property="id" />
 <result column="user_name" property="userName" />
 <result column="nick_name" property="nickName" />
 <result column="avatar" property="avatar" />
 <result column="email" property="email" />
 <result column="signature" property="signature" />
 <result column="create_time" property="createTime" />
 <result column="update_time" property="updateTime" />
 <result column="del_flag" property="delFlag" />

 <collection property="tpluginModels" column="id" ofType="com.example.demo.model.TpluginModel"
 select="pluginByUid" /> //column='id' 为关联查询所需条件
 </resultMap>

sql语句使用两个sql语句返回结果

 <select id="selectTuserBynameOrNick" resultMap="extendMapper"> SELECT
 * FROM t_user WHERE del_flag = 0 AND ( user_name LIKE CONCAT( '%', #{name},'%')
 OR nick_name LIKE CONCAT( '%', #{name},'%')) </select>
//下个sql语句依赖上个
<select id="pluginByUid" resultType="com.example.demo.model.TpluginModel"> SELECT id,user_id as
 userId,name,icon,vsersion,tags,description,
 create_time as createTime ,update_time as updateTime ,del_flag as delFlag
 FROM t_plugin WHERE del_flag = 0 AND user_id = #{id}
 </select>

补充知识：Mybatis 一个dao 对应多个Mapper.xml

由于项目中的mybatis的mapper是用mybatis generator自动生成的，但是生成的mapper满足不了我的业务，需要自己扩展，所以就研究了下、

添加接口

创建mapper.xml

修改配置

1.添加接口

在原dao中加个接口

/** ---------------自定义Mapper--------------- **/

List<PcacheCluster> select(ClusterInstanceBO clusterInstanceBO);

2. 创建mapper.xml

PcacheClusterMapperExtend.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="com.oppo.paas.pcache.manager.mapper.PcacheTemplateMapper">

 <select id="select" parameterType="com.oppo.paas.pcache.manager.entity.PcacheTemplate" resultMap="BaseResultMap">
 select
 <include refid="Base_Column_List" />
 from t_pcache_template 

 <where>
 <if test="templateId != null and templateId != ''">
  and template_id = #{templateId}
 </if>
 <if test="templateName != null and templateName != ''">
  and template_name = #{templateName}
 </if>
 <if test="templateType != null and templateType != ''">
  and template_type = #{templateType}
 </if>
 <if test="createUser != null and createUser != ''">
  and create_user = #{createUser}
 </if>
 <if test="createTime != null ">
  and create_time = #{createTime,jdbcType=TIMESTAMP}
 </if>
 </where>
 order by create_time desc
 </select>
</mapper>

3. 修改配置

项目目录：

添加mapper扫描路径

 <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
 <property name="dataSource" ref="dataSource"/>
 <!-- 自动扫描mapping.xml文件 -->
 <property name="mapperLocations" >
  <array>
  <value>classpath:mybatis/mappers/*Mapper.xml</value>
  <!-- 扩展mapper.xml -->
  <value>classpath:mybatis/mappers/extend/*MapperExtend.xml</value>
  </array>

 </property>
 <property name="configLocation" value="classpath:mybatis/mybatis-config.xml"></property>
 <property name="plugins">
  <array>
  <bean class="com.github.pagehelper.PageInterceptor">
   <!-- 这里的几个配置主要演示如何使用，如果不理解，一定要去掉下面的配置 -->
   <property name="properties">
   <value>
    helperDialect=mysql
    reasonable=true
    supportMethodsArguments=true
    params=count=countSql
    autoRuntimeDialect=true
   </value>
   </property>
  </bean>
  </array>
 </property>
 </bean>

mybatis generator 已经过时了哦，太麻烦，耦合性高，建议使用通用Mapper，完美继承spring，springboot

学习地址：https://gitee.com/free/Mapper/wikis/Home

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