写一个简单的springboot集合mybatis的代码

这里提供一个简单的Spring Boot集成MyBatis的示例代码：

1. 首先在pom.xml中添加以下依赖：

<dependency>
   <groupId>org.springframework.boot</groupId>
   <artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
   <groupId>org.mybatis.spring.boot</groupId>
   <artifactId>mybatis-spring-boot-starter</artifactId>
   <version>2.1.4</version>
</dependency>
<dependency>
   <groupId>com.h2database</groupId>
   <artifactId>h2</artifactId>
   <version>1.4.200</version>
   <scope>runtime</scope>
</dependency>

2. 创建一个实体类User.java：

public class User {
   private Long id;
   private String name;
   private Integer age;
   // 省略getter和setter方法
}

3. 创建一个Mapper接口UserMapper.java：

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

   @Insert("INSERT INTO users(name, age) VALUES(#{name}, #{age})")
   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);
}

4. 创建一个MyBatis配置文件application.yml：

mybatis:
  mapper-locations: classpath:mapper/*.xml
  type-aliases-package: com.example.demo.entity

5. 在resources目录下创建一个mapper目录，然后在mapper目录下创建一个UserMapper.xml文件：

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

   <select id="findById" 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="Long">
      DELETE FROM users WHERE id=#{id}
   </delete>
</mapper>

6. 创建一个Controller类UserController.java：

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

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

   @PostMapping("/users")
   public String saveUser(@RequestBody User user) {
      userMapper.save(user);
      return "success";
   }

   @PutMapping("/users")
   public String updateUser(@RequestBody User user) {
      userMapper.update(user);
      return "success";
   }

   @DeleteMapping("/users/{id}")
   public String deleteUser(@PathVariable Long id) {
      userMapper.delete(id);
      return "success";
   }
}

7. 运行Spring Boot应用，访问http://localhost:8080/users/{id}可以获取指定id的用户信息，访问http://localhost:8080/users可以新增用户，访问http://localhost:8080/users可以更新用户信息，访问http://localhost:8080/users/{id}可以删除指定id的用户。