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 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 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 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 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

以上这篇mybatis一对多两种mapper写法实例就是小编分享给大家的全部内容了，希望能给大家一个参考，也希望大家多多支持好吧啦网。