依赖：
mybatis-plus、lombok、hutool、mysql-dirver
<?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>2.7.8</version><relativePath/> <!-- lookup parent from repository --></parent><groupId>com.example</groupId><artifactId>my-dianping</artifactId><version>0.0.1-SNAPSHOT</version><name>my-dianping</name><description>Demo project for Spring Boot</description><url/><licenses><license/></licenses><developers><developer/></developers><scm><connection/><developerConnection/><tag/><url/></scm><properties><java.version>17</java.version></properties><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-data-redis-reactive</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</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>io.projectreactor</groupId><artifactId>reactor-test</artifactId><scope>test</scope></dependency><dependency><groupId>com.baomidou</groupId><artifactId>mybatis-plus-boot-starter</artifactId><version>3.4.3</version></dependency><dependency><groupId>cn.hutool</groupId><artifactId>hutool-all</artifactId><version>5.7.17</version></dependency><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><optional>true</optional></dependency></dependencies><build><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId></plugin></plugins></build></project>yml 配置文件：
server:port: 8080spring:datasource:url: jdbc:mysql://localhost:3306/learnbaseusername: rootpassword: 1234测试是否成功连接数据库：
先创建持久层的 UserMapper 继承 mybatis-plus 的方法
@Mapper
public interface UserMapper extends BaseMapper<User> {}tb_user 表的封装类 pojo
@Data
@EqualsAndHashCode(callSuper = false)
@Accessors(chain = true)
@TableName("tb_user")
public class User implements Serializable {private static final long serialVersionUID = 1L;/*** 主键*/@TableId(value = "id", type = IdType.AUTO)private Long id;/*** 手机号码*/private String phone;/*** 密码，加密存储*/private String password;/*** 昵称，默认是随机字符*/private String nickName;/*** 用户头像*/private String icon = "";/*** 创建时间*/private LocalDateTime createTime;/*** 更新时间*/private LocalDateTime updateTime;}测试
@SpringBootTest
class MyDianpingApplicationTests {@Autowiredprivate UserMapper userMapper;@Testvoid contextLoads() {User user = userMapper.selectById(1);System.out.println(user);}}控制台输出了查询到的数据，则表示连接没有问题
