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MyBatisX插件

在真正开发过程中对于一些复杂的SQL和多表联查就需要我们自己去编写代码和SQL语句,这个时候可以使用MyBatisX插件帮助我们简化开发

• 安装MyBatisX插件: File -> Settings -> Plugins -> 搜索MyBatisx插件搜索安装然后重启IDEA

跳转文件功能

由于一个项目中的mapper接口和映射文件有很多找起来很麻烦, 而MyBatisX插件可以快速找到mapper接口对应的映射文件以及映射文件对应的mapper接口

在application.xml文件中指定SQL映射文件的位置,mybatis-plus的mapper-locations属性可以指定配置文件的位置(默认从类路径下的mapper目录下加载)

mybatis-plus:configuration:log-impl: org.apache.ibatis.logging.stdout.StdOutImpl#设置MyBatis-Plus的全局配置mapper-locations: SQL映射文件的路径

代码生成功能

第一部: 创建一个Spring Boot工程并引入相关依赖, 在application.yml文件中配置数据源的连接信息

spring:# 配置数据源信息datasource:# 配置数据源类型(Spring boot默认使用的数据源)type: com.zaxxer.hikari.HikariDataSource# 配置连接数据库的各个信息driver-class-name: com.mysql.cj.jdbc.Driverurl: jdbc:mysql://localhost:3306/mybatis_plus?characterEncoding=utf-8&userSSL=falseusername: rootpassword: 123456

<dependencies><dependency><!--spring boot的启动器--><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter</artifactId></dependency><dependency><!--spring boot的测试启动器--><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency><dependency><!--mybatis-plus的启动器--><groupId>com.baomidou</groupId><artifactId>mybatis-plus-boot-starter</artifactId><version>3.5.1</version></dependency><dependency><!--简化实体类开发的依赖(还需要下载lombok插件)--><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><optional>true</optional></dependency><dependency><!--mysql的驱动,Spring boot默认的是8以上的版本--><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><scope>runtime</scope></dependency>
</dependencies>

第二步: 在IDEA的Database中设置参数连接本地的MySQL数据库

第三步: 使用MyBatisX插件设置生成表相关的mapper,service,映射文件的存放位置

查看mapper接口,mapper接口的映射文件,service接口及其实现类的最终生成位置

自定义方法和SQL

根据mapper接口中的自定义的模板方法名在SQL映射文件中生成对应的增删改查的SQL语句,自动将mapper接口中的方法与映射文件的SQL语句相关联

• 自定义增删改查的方法时一般以insert,select,update,delete为前缀

public interface UserMapper extends BaseMapper<User> {//添加数据时,如果实体类属性为null则不为该属性对应的字段赋值int insertSelective(User user);//根据uid和username删除用户int deleteByUidAndUserName(@Param("uid") Long uid, @Param("userName") String userName);//根据uid更新用户的年龄和性别int updateAgeAndSexByUid(@Param("age") Integer age, @Param("sex") Integer sex, @Param("uid") Long uid);//查询年龄和性别根据年龄的区间范围List<User> selectAgeAndSexByAgeBetween(@Param("beginAge") Integer beginAge, @Param("endAge") Integer endAge);//查询所有字段根据年龄降序List<User> selectAllOrderByAgeDesc();
}

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapperPUBLIC "-//mybatis.org//DTD Mapper 3.0//EN""http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.atguigu.mybatisx.mapper.UserMapper"><resultMap id="BaseResultMap" type="com.atguigu.mybatisx.pojo.User"><id property="uid" column="uid" jdbcType="BIGINT"/><result property="userName" column="user_name" jdbcType="VARCHAR"/><result property="age" column="age" jdbcType="INTEGER"/><result property="email" column="email" jdbcType="VARCHAR"/><result property="sex" column="sex" jdbcType="INTEGER"/><result property="isDeleted" column="is_deleted" jdbcType="INTEGER"/></resultMap><!--SQL片段,记录表中的所有字段--><sql id="Base_Column_List">uid,user_name,age,email,sex,is_deleted</sql><!--int insertSelective(User user);--><insert id="insertSelective">insert into t_user<trim prefix="(" suffix=")" suffixOverrides=","><if test="uid != null">uid,</if><if test="userName != null">user_name,</if><if test="age != null">age,</if><if test="email != null">email,</if><if test="sex != null">sex,</if><if test="isDeleted != null">is_deleted,</if></trim>values<trim prefix="(" suffix=")" suffixOverrides=","><if test="uid != null">#{uid,jdbcType=BIGINT},</if><if test="userName != null">#{userName,jdbcType=VARCHAR},</if><if test="age != null">#{age,jdbcType=INTEGER},</if><if test="email != null">#{email,jdbcType=VARCHAR},</if><if test="sex != null">#{sex,jdbcType=INTEGER},</if><if test="isDeleted != null">#{isDeleted,jdbcType=INTEGER},</if></trim></insert><!--int deleteByUidAndUserName(@Param("uid") Long uid, @Param("userName") String userName);--><delete id="deleteByUidAndUserName">delete from t_user where uid = #{uid,jdbcType=NUMERIC} AND user_name = #{userName,jdbcType=VARCHAR}</delete><!--int updateAgeAndSexByUid(@Param("age") Integer age, @Param("sex") Integer sex, @Param("uid") Long uid);--><update id="updateAgeAndSexByUid">update t_user set age = #{age,jdbcType=NUMERIC},sex = #{sex,jdbcType=NUMERIC} where uid = #{uid,jdbcType=NUMERIC}</update><!--List<User> selectAgeAndSexByAgeBetween(@Param("beginAge") Integer beginAge, @Param("endAge") Integer endAge);--><select id="selectAgeAndSexByAgeBetween" resultMap="BaseResultMap">select age, sex from t_user where age between #{beginAge,jdbcType=INTEGER} and #{endAge,jdbcType=INTEGER}</select><!--List<User> selectAllOrderByAgeDesc();--><select id="selectAllOrderByAgeDesc" resultMap="BaseResultMap">select <include refid="Base_Column_List"/> from  t_user order by age desc</select>
</mapper>