用springboot mybatis写一个增删改查

1. 首先需要在pom.xml文件中添加依赖：

<dependency>
    <groupId>org.mybatis.spring.boot</groupId>
    <artifactId>mybatis-spring-boot-starter</artifactId>
    <version>2.2.0</version>
</dependency>

2. 在application.properties文件中配置数据库连接信息：

spring.datasource.url=jdbc:mysql://localhost:3306/test?useSSL=false&serverTimezone=UTC
spring.datasource.username=root
spring.datasource.password=123456
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

3. 创建实体类User：

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

    // getter和setter方法省略
}

4. 创建Mapper接口UserMapper：

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

5. 在application类中添加MapperScan注解：

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

6. 在Controller中注入UserMapper并实现增删改查：

@RestController
public class UserController {
    @Autowired
    private UserMapper userMapper;

    @GetMapping("/user/{id}")
    public User findById(@PathVariable("id") Integer id) {
        return userMapper.findById(id);
    }

    @PostMapping("/user")
    public void save(User user) {
        userMapper.save(user);
    }

    @PutMapping("/user")
    public void update(User user) {
        userMapper.update(user);
    }

    @DeleteMapping("/user/{id}")
    public void delete(@PathVariable("id") Integer id) {
        userMapper.delete(id);
    }
}