DROP TABLE IF EXISTS `user`;
CREATE TABLE `user` (
    id BIGINT NOT NULL AUTO_INCREMENT COMMENT '主键ID',
    name VARCHAR(30) DEFAULT NULL COMMENT '姓名',
    age INT DEFAULT NULL COMMENT '年龄',
    email VARCHAR(50) DEFAULT NULL COMMENT '邮箱',
    PRIMARY KEY (id)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COMMENT='用户表';

DELETE FROM `user`;
INSERT INTO `user` (id, name, age, email) VALUES
(1, 'Jone', 18, 'test1@baomidou.com'),
(2, 'Jack', 20, 'test2@baomidou.com'),
(3, 'Tom', 28, 'test3@baomidou.com'),
(4, 'Sandy', 21, 'test4@baomidou.com'),
(5, 'Billie', 24, 'test5@baomidou.com');

resources/
└── db/
    ├── schema-mysql.sql
    └── data-mysql.sql

com.example.mpdemo/
├── MpdemoApplication.java  # Spring Boot 启动类
├── entity/                 # 实体类包
│   └── User.java
├── mapper/                 # Mapper 接口包
│   └── UserMapper.java
└── test/                   # 测试类包
    └── MpdemoApplicationTests.java

<?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>
    <!-- Spring Boot 3 父工程（稳定版） -->
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>3.5.13</version>
        <relativePath/>
    </parent>

    <groupId>com.example</groupId>
    <artifactId>mpdemo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>mpdemo</name>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>

        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-spring-boot4-starter</artifactId>
            <version>3.5.15</version>
        </dependency>

        <dependency>
            <groupId>com.mysql</groupId>
            <artifactId>mysql-connector-j</artifactId>
            <scope>runtime</scope>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <excludes>
                        <exclude>
                            <groupId>org.projectlombok</groupId>
                            <artifactId>lombok</artifactId>
                        </exclude>
                    </excludes>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

spring:
  # MySQL 数据源配置
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/mybatis_plus_demo?useUnicode=true&characterEncoding=utf8&serverTimezone=Asia/Shanghai&useSSL=false
    username: root       # 你的 MySQL 用户名
    password: root       # 你的 MySQL 密码
  # 自动初始化数据库脚本
  sql:
    init:
      schema-locations: classpath:db/schema-mysql.sql
      data-locations: classpath:db/data-mysql.sql
      mode: always

# MyBatis-Plus 配置（打印SQL日志，方便调试）
mybatis-plus:
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl

package com.example.mpdemo.entity;

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

@Data
@TableName("user") // 映射数据库表名
public class User {
    private Long id;       // 主键ID
    private String name;   // 姓名
    private Integer age;   // 年龄
    private String email;  // 邮箱
}

package com.example.mpdemo.mapper;

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.example.mpdemo.entity.User;

public interface UserMapper extends BaseMapper<User> {
    // 无需手写任何SQL方法
}

package com.example.mpdemo;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
@MapperScan("com.example.mpdemo.mapper") // 扫描 Mapper 接口包路径
public class MpdemoApplication {
    public static void main(String[] args) {
        SpringApplication.run(MpdemoApplication.class, args);
    }
}

package com.example.mpdemo;

import com.example.mpdemo.entity.User;
import com.example.mpdemo.mapper.UserMapper;
import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import java.util.List;

@SpringBootTest
class MpdemoApplicationTests {

    @Autowired
    private UserMapper userMapper;

    @Test
    void testSelectAllUser() {
        System.out.println("----- 测试：查询所有用户数据 -----");
        // 无条件查询全表
        List<User> userList = userMapper.selectList(null);
        
        // 断言数据条数为5
        Assertions.assertEquals(5, userList.size());
        
        // 打印用户数据
        userList.forEach(System.out::println);
    }
}

User(id=1, name=Jone, age=18, email=test1@baomidou.com)
User(id=2, name=Jack, age=20, email=test2@baomidou.com)
User(id=3, name=Tom, age=28, email=test3@baomidou.com)
User(id=4, name=Sandy, age=21, email=test4@baomidou.com)
User(id=5, name=Billie, age=24, email=test5@baomidou.com)