springmyboot+batis的代码（代码要有注释）写一个，带有依赖，yml配置，mapper.xml，entity，mapper，service，controller，application

代码如下：

1. 依赖配置（pom.xml）

<!-- Spring Boot -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>

<!-- MyBatis -->
<dependency>
    <groupId>org.mybatis.spring.boot</groupId>
    <artifactId>mybatis-spring-boot-starter</artifactId>
    <version>2.1.4</version>
</dependency>

<!-- MySQL Connector -->
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.23</version>
</dependency>

2. 配置文件（application.yml）

spring:
  datasource:
    url: jdbc:mysql://localhost:3306/db_example
    username: root
    password: root
    driver-class-name: com.mysql.cj.jdbc.Driver

mybatis:
  mapper-locations: classpath:/mapper/*.xml

3. 实体类（User.java）

public class User {
    private Long id;
    private String name;
    private Integer age;

    // getters and setters
}

4. Mapper 接口（UserMapper.java）

@Mapper
public interface UserMapper {
    @Select("SELECT * FROM users")
    List<User> findAll();

    @Select("SELECT * FROM users WHERE id = #{id}")
    User findById(Long id);

    @Insert("INSERT INTO users(name, age) VALUES(#{name}, #{age})")
    @Options(useGeneratedKeys = true, keyProperty = "id")
    void save(User user);

    @Update("UPDATE users SET name=#{name}, age=#{age} WHERE id=#{id}")
    void update(User user);

    @Delete("DELETE FROM users WHERE id=#{id}")
    void delete(Long id);
}

5. Service 层（UserService.java）

@Service
public class UserService {
    private final UserMapper userMapper;

    @Autowired
    public UserService(UserMapper userMapper) {
        this.userMapper = userMapper;
    }

    public List<User> findAll() {
        return userMapper.findAll();
    }

    public User findById(Long id) {
        return userMapper.findById(id);
    }

    public void save(User user) {
        userMapper.save(user);
    }

    public void update(User user) {
        userMapper.update(user);
    }

    public void delete(Long id) {
        userMapper.delete(id);
    }
}

6. Controller 层（UserController.java）

@RestController
@RequestMapping("/users")
public class UserController {
    private final UserService userService;

    @Autowired
    public UserController(UserService userService) {
        this.userService = userService;
    }

    @GetMapping("")
    public List<User> findAll() {
        return userService.findAll();
    }

    @GetMapping("/{id}")
    public User findById(@PathVariable Long id) {
        return userService.findById(id);
    }

    @PostMapping("")
    public void save(@RequestBody User user) {
        userService.save(user);
    }

    @PutMapping("/{id}")
    public void update(@PathVariable Long id, @RequestBody User user) {
        user.setId(id);
        userService.update(user);
    }

    @DeleteMapping("/{id}")
    public void delete(@PathVariable Long id) {
        userService.delete(id);
    }
}

7. 启动类（Application.java）

@SpringBootApplication
@MapperScan("com.example.demo.mapper")
public class Application {
    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }
}

8. Mapper 文件（UserMapper.xml）

<mapper namespace="com.example.demo.mapper.UserMapper">

    <resultMap id="userMap" type="com.example.demo.entity.User">
        <id property="id" column="id" />
        <result property="name" column="name" />
        <result property="age" column="age" />
    </resultMap>

    <select id="findAll" resultMap="userMap">
        SELECT * FROM users
    </select>

    <select id="findById" parameterType="java.lang.Long" resultMap="userMap">
        SELECT * FROM users WHERE id = #{id}
    </select>

    <insert id="save" parameterType="com.example.demo.entity.User">
        INSERT INTO users(name, age) VALUES(#{name}, #{age})
    </insert>

    <update id="update" parameterType="com.example.demo.entity.User">
        UPDATE users SET name=#{name}, age=#{age} WHERE id=#{id}
    </update>

    <delete id="delete" parameterType="java.lang.Long">
        DELETE FROM users WHERE id=#{id}
    </delete>

</mapper>