一、新建项目：com.saas.plusdemo

二、配置pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>3.2.1</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.saas</groupId>
    <artifactId>plusdemo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>com.saas.plusdemo</name>
    <description>com.saas.plusdemo</description>
    <properties>
        <java.version>17</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>
        <!--MyBatis Plus 依赖-->
        <dependency> <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.0.3</version>
        </dependency>
        <dependency> <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus</artifactId>
            <version>3.0.3</version>
        </dependency>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis-spring</artifactId>
            <version>3.0.3</version>
        </dependency>
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-generator</artifactId>
            <version>3.3.1</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>
        <dependency>
            <groupId>com.mysql</groupId>
            <artifactId>mysql-connector-j</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-extension</artifactId>
            <version>3.5.5</version>
            <scope>compile</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

三、配置application.yml

spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://192.168.31.132:3306/linq2db
    username: root
    password: 123456

mybatis-plus:
  configuration:
    #  取消驼峰命名映射
    map-underscore-to-camel-case: false
    #    配置日志
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl

添加一个：Myconfig 非常重要一定要配

package com.saas.plusdemo;

import com.baomidou.mybatisplus.extension.spring.MybatisSqlSessionFactoryBean;
import org.apache.ibatis.session.SqlSessionFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import javax.sql.DataSource;

@Configuration
public class Myconfig {
    @Autowired
    @Qualifier("dataSource")
    private DataSource dataSource;

    @Bean
    //判定配置文件中的配置属性
    @ConfigurationProperties(prefix = "mybatis-plus")
    public SqlSessionFactory sqlSessionFactory() throws Exception {
        MybatisSqlSessionFactoryBean sqlSessionFactoryBean = new MybatisSqlSessionFactoryBean();
        //设置数据源
        sqlSessionFactoryBean.setDataSource(dataSource);
        return sqlSessionFactoryBean.getObject();
    }
}

四、添加实体类Product

package com.saas.plusdemo;

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

@Data
@TableName("product")
public class Product {
   private   String id;

   private  String name;


    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

添加数据库访问仓储：IProductRepository

package com.saas.plusdemo.mapper;

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.saas.plusdemo.Product;

public interface IProductRepository extends BaseMapper<Product> {
}

添加到容器Application

package com.saas.plusdemo;

import com.saas.plusdemo.mapper.IProductRepository;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.ConfigurableApplicationContext;
import org.mybatis.spring.annotation.MapperScan;
@SpringBootApplication
@MapperScan({"com.saas.plusdemo.mapper"})
public class Application {

    public static void main(String[] args) {
        ConfigurableApplicationContext ctx= SpringApplication.run(Application.class, args);
        var bean=  ctx.getBean(IProductRepository.class);
    }

}

测试：

package com.saas.plusdemo;

import com.saas.plusdemo.mapper.IProductRepository;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

@SpringBootTest
class ApplicationTests {

    @Autowired
    private IProductRepository productRepository;
    @Test
    void contextLoads() {
        Product  product= productRepository.selectById("7cde8fb3-eff9-38e9-5722-3a09e672b985");
    }

}