1.引入依赖

     <dependency><groupId>com.baomidou</groupId><artifactId>mybatis-plus-boot-starter</artifactId><version>3.4.3</version></dependency>

2.不能使用mybatis的数据源，使用mybatisPlus的

注意： 如果有mybatis的注释掉就行

package com.ruoyi.framework.config;import com.baomidou.mybatisplus.annotation.DbType;
import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;
import com.baomidou.mybatisplus.extension.plugins.inner.BlockAttackInnerInterceptor;
import com.baomidou.mybatisplus.extension.plugins.inner.OptimisticLockerInnerInterceptor;
import com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.transaction.annotation.EnableTransactionManagement;/*** Mybatis Plus 配置** @author ruoyi*/
@EnableTransactionManagement(proxyTargetClass = true)
@Configuration
public class MybatisPlusConfig
{@Beanpublic MybatisPlusInterceptor mybatisPlusInterceptor(){MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();// 分页插件interceptor.addInnerInterceptor(paginationInnerInterceptor());// 乐观锁插件interceptor.addInnerInterceptor(optimisticLockerInnerInterceptor());// 阻断插件interceptor.addInnerInterceptor(blockAttackInnerInterceptor());return interceptor;}/*** 分页插件，自动识别数据库类型 https://baomidou.com/guide/interceptor-pagination.html*/public PaginationInnerInterceptor paginationInnerInterceptor(){PaginationInnerInterceptor paginationInnerInterceptor = new PaginationInnerInterceptor();// 设置数据库类型为mysqlpaginationInnerInterceptor.setDbType(DbType.MYSQL);// 设置最大单页限制数量，默认 500 条，-1 不受限制paginationInnerInterceptor.setMaxLimit(-1L);return paginationInnerInterceptor;}/*** 乐观锁插件 https://baomidou.com/guide/interceptor-optimistic-locker.html*/public OptimisticLockerInnerInterceptor optimisticLockerInnerInterceptor(){return new OptimisticLockerInnerInterceptor();}/*** 如果是对全表的删除或更新操作，就会终止该操作 https://baomidou.com/guide/interceptor-block-attack.html*/public BlockAttackInnerInterceptor blockAttackInnerInterceptor(){return new BlockAttackInnerInterceptor();}
}

3.配置yml文件

# MyBatis配置
#mybatis:
#  # 搜索指定包别名
#  typeAliasesPackage: com.ruoyi.**.domain
#  # 配置mapper的扫描，找到所有的mapper.xml映射文件
#  mapperLocations: classpath*:mapper/**/*.xml
#  # 加载全局的配置文件
#  configLocation: classpath:mybatis/mybatis-config.xml
mybatis-plus:# 搜索指定包别名typeAliasesPackage: com.ruoyi.**.domain# 配置mapper的扫描，找到所有的mapper.xml映射文件mapperLocations: classpath*:mapper/**/*Mapper.xml# 加载全局的配置文件configLocation: classpath:mybatis/mybatis-config.xml#这个不要和上面的那个配置在一起会报错，换个地方配置就行configuration:map-underscore-to-camel-case: true

最后： 所有的Mapper继承 BaseMapper就行，就可以使用它的相关的方法了，或者用service继承相关的一些东西。