<dependencies>
    <!-- Spring Boot Web -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <!-- MyBatis-Spring-Boot-Starter -->
    <dependency>
        <groupId>org.mybatis.spring.boot</groupId>
        <artifactId>mybatis-spring-boot-starter</artifactId>
        <version>3.0.3</version>
    </dependency>
    <!-- 數(shù)據(jù)庫驅(qū)動 -->
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-j</artifactId>
        <scope>runtime</scope>
    </dependency>
    <!-- Lombok（可選） -->
    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <optional>true</optional>
    </dependency>
</dependencies>

spring:
  datasource:
    url: jdbc:mysql://localhost:3306/demo_db?useSSL=false&serverTimezone=Asia/Shanghai
    username: root
    password: root123
    driver-class-name: com.mysql.cj.jdbc.Driver
mybatis:
  # 指定 Mapper XML 文件位置
  mapper-locations: classpath:mapper/*.xml
  # 指定實體類包，自動映射列名和屬性名（開啟駝峰命名）
  type-aliases-package: com.example.demo.entity
  configuration:
    map-underscore-to-camel-case: true

package com.example.demo.entity;
import lombok.Data;
@Data
public class User {
    private Long id;
    private String username;
    private String email;
}

package com.example.demo.mapper;
import com.example.demo.entity.User;
import org.apache.ibatis.annotations.*;
import java.util.List;
@Mapper
public interface UserMapper {
    @Select("SELECT * FROM user WHERE id = #{id}")
    User findById(Long id);
    @Select("SELECT * FROM user")
    List<User> findAll();
    @Insert("INSERT INTO user(username, email) VALUES(#{username}, #{email})")
    @Options(useGeneratedKeys = true, keyProperty = "id")
    int insert(User user);
    @Update("UPDATE user SET username=#{username}, email=#{email} WHERE id=#{id}")
    int update(User user);
    @Delete("DELETE FROM user WHERE id=#{id}")
    int delete(Long id);
}

<?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.example.demo.mapper.UserMapper">
    <select id="findAll" resultType="com.example.demo.entity.User">
        SELECT * FROM user
    </select>
    <insert id="insert" parameterType="com.example.demo.entity.User" useGeneratedKeys="true" keyProperty="id">
        INSERT INTO user(username, email) VALUES(#{username}, #{email})
    </insert>
</mapper>

package com.example.demo.service;
import com.example.demo.entity.User;
import com.example.demo.mapper.UserMapper;
import org.springframework.stereotype.Service;
import java.util.List;
@Service
public class UserService {
    private final UserMapper userMapper;
    public UserService(UserMapper userMapper) {
        this.userMapper = userMapper;
    }
    public User getUser(Long id) {
        return userMapper.findById(id);
    }
    public List<User> listUsers() {
        return userMapper.findAll();
    }
    public int addUser(User user) {
        return userMapper.insert(user);
    }
}

package com.example.demo.controller;
import com.example.demo.entity.User;
import com.example.demo.service.UserService;
import org.springframework.web.bind.annotation.*;
import java.util.List;
@RestController
@RequestMapping("/users")
public class UserController {
    private final UserService userService;
    public UserController(UserService userService) {
        this.userService = userService;
    }
    @GetMapping("/{id}")
    public User getUser(@PathVariable Long id) {
        return userService.getUser(id);
    }
    @GetMapping
    public List<User> listUsers() {
        return userService.listUsers();
    }
    @PostMapping
    public String addUser(@RequestBody User user) {
        userService.addUser(user);
        return "User added successfully!";
    }
}

<dependency>
    <groupId>com.github.pagehelper</groupId>
    <artifactId>pagehelper-spring-boot-starter</artifactId>
    <version>1.4.7</version>
</dependency>

PageHelper.startPage(1, 10);
List<User> users = userMapper.findAll();
PageInfo<User> pageInfo = new PageInfo<>(users);