spring boot + mybatis 简单示例

好的，以下是一个简单的 Spring Boot + Mybatis 示例：

1. 首先，在 pom.xml 中添加以下依赖：

<dependencies>
    <!-- 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>2.0.6</version>
    </dependency>
  
    <!-- MySQL 连接驱动 -->
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>8.0.21</version>
    </dependency>
</dependencies>

2. 在 application.yml 中配置数据库连接信息：

spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone=UTC
    username: root
    password: root

3. 创建一个 User 实体类：

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

    // getter 和 setter
}

4. 创建一个 UserMapper 接口：

@Mapper
public interface UserMapper {
    @Select("SELECT * FROM user WHERE id = #{id}")
    User findById(Long id);

    @Insert("INSERT INTO user(name, age) VALUES(#{name}, #{age})")
    void save(User user);

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

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

5. 创建一个 UserService 类，实现业务逻辑：

@Service
public class UserService {
    @Autowired
    private UserMapper userMapper;

    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. 创建一个 UserController 类，处理 HTTP 请求：

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

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

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

    @PutMapping
    public void update(@RequestBody User user) {
        userService.update(user);
    }

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

这样，一个简单的 Spring Boot + Mybatis 示例就完成了。你可以使用 Postman 或者浏览器访问 http://localhost:8080/users/{id} 等接口测试。