Spring cloud 引入MyBatis-Plus

MyBatis-Plus是一个MyBatis的增强工具，在MyBatis的基础上只做增强不做改变，为简化开发、提高效率而生。

一、引入MyBatis-Plus依赖

在build.gradle文件中的dependencies的对象中引入依赖

implementation 'com.baomidou:mybatis-plus-boot-starter:3.4.2'

引入MyBatis-Plus之后请不要再次引入MyBatis以及MyBatis-Spring，以避免因版本差异导致的问题。

二、application.xml配置mybatis-plus

mybatis-plus:
  # mybatis的sql xml映射文件，配置在resources文件夹下
  mapper-locations: classpath:mybatis/*Mapper.xml
  # 数据库表字段实体
  typeAliasesPackage: com.pd.shop.model.entity

三、配置Application的mapper扫描路径

@SpringBootApplication
@MapperScan(basePackages = "com.pd.shop.mapper")
public class ShopApplication {
    public static void main(String[] args) {
        SpringApplication.run(ShopApplication.class, args);
    }
}

四、封装基类MyBatis-Plus

建议一下封装基类,后续进行扩展方便，当然也可以不封装
对于继承的BaseMapper接口、IService接口、继承ServiceImpl实现类

(1) 继承MyBatis-Plus的BaseMapper

package com.pd.shop.mapper;

import com.baomidou.mybatisplus.core.mapper.BaseMapper;

public interface IShopMapper<T> extends BaseMapper<T> {

}

(2) 继承MyBatis-Plus的IService

package com.pd.shop.service;

import com.baomidou.mybatisplus.extension.service.IService;

public interface IShopService<T> extends IService<T> {

}

(3) 继承MyBatis-Plus的ServiceImpl<M, T>

package com.pd.shop.service.impl;

import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.pd.shop.mapper.IShopMapper;
import com.pd.shop.service.IShopService;

public class ShopImpl<M extends IShopMapper<T>, T> extends ServiceImpl<M, T> implements IShopService<T> {
    
}

五、新建实体类

对应步骤二中, mybatis-plus.typeAliasesPackage配置

package com.pd.shop.model.entity;

import com.baomidou.mybatisplus.annotation.TableName;
import lombok.Data;

@Data
@TableName("user_info")
public class UserInfo {

    private static final long serialVersionUID = 1L;

    private Long id;

    /**
     * 用户昵称
     */
    private String nickname;


    /**
     * 1男 0女 -1未知
     */
    private Integer sex;
}

六、新建mybatis的sql xml映射文件

新建UserInfoMapper.xml resources/mybatis文件夹下，对应步骤二中, mybatis-plus.mapper-locations 配置

<?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.pd.shop.mapper.UserInfoMapper">

    <select id="queryList" resultType="com.pd.shop.model.entity.UserInfo">
        SELECT
        id,
        nickname,
        sex
        FROM
        user_info
    </select>
</mapper>

推荐MybatisX快速开发插件。可以进行跳转，提示等辅助开发功能

七、继承基类

(1) Mapper继承新的IShopMapper,

package com.pd.shop.mapper;

import com.pd.shop.model.entity.UserInfo;

import java.util.List;

public interface UserInfoMapper extends IShopMapper<UserInfo> {

    List<UserInfo> queryList();
}

(2) Service继承新的IShopService,

package com.pd.shop.service;

import com.pd.shop.model.entity.UserInfo;

import java.util.List;

public interface UserInfoService extends IShopService<UserInfo> {

    List<UserInfo> queryList();
}

(3) Impl继承新的ShopImpl

package com.pd.shop.service.impl;

import com.pd.shop.mapper.UserInfoMapper;
import com.pd.shop.model.entity.UserInfo;
import com.pd.shop.service.UserInfoService;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Service;

import java.util.List;

@Service
public class UserInfoImpl extends ShopServiceImpl<UserInfoMapper, UserInfo> implements UserInfoService {

    @Override
    public List<UserInfo> queryList(){
        UserInfo userInfo= baseMapper.selectById("1336601236750163969");
        //.... baseMapper.
        //.... this.
        //.... 可以调用MyBatis-Plus的方法
        return baseMapper.queryList();
    }
}