SpringBoot集成MyBatis

### MyBatis集成

MyBatis是一个优秀的持久层框架，它封装了JDBC，使开发者只需要关注SQL语句本身。MyBatis通过XML或注解的方式配置statement，并通过Java对象和SQL的动态参数映射生成最终执行的SQL语句。以下是整合MyBatis的步骤：

1. **添加依赖**：在项目的`pom.xml`文件中添加MyBatis的依赖。
   ```xml
   <dependency>
       <groupId>org.mybatis</groupId>
       <artifactId>mybatis</artifactId>
       <version>3.5.6</version> 
   </dependency>
   <dependency>
       <groupId>mysql</groupId>
       <artifactId>mysql-connector-java</artifactId>
       <version>8.0.23</version> 
   </dependency>
   ```

2. **创建MyBatis配置文件**：在`src/main/resources`目录下创建`mybatis-config.xml`文件，用于配置MyBatis。
   ```xml
   <?xml version="1.0" encoding="UTF-8" ?>
   <!DOCTYPE configuration
           PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
           "http://mybatis.org/dtd/mybatis-3-config.dtd">
   <configuration>
       <environments default="development">
           <environment id="development">
               <transactionManager type="JDBC"/>
               <dataSource type="POOLED">
                   <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                   <property name="url" value="jdbc:mysql://localhost:3306/your_database"/>
                   <property name="username" value="root"/>
                   <property name="password" value="your_password"/>
               </dataSource>
           </environment>
       </environments>
       <mappers>
           <mapper resource="com/example/mapper/UserMapper.xml"/>
       </mappers>
   </configuration>
   ```

3. **创建数据模型**：在`src/main/java`下创建一个用户数据模型类`User.java`。
   ```java
   package com.example.model;
   public class User {
       private int id;
       private String name;
       // Getter和Setter方法
   }
   ```

4. **创建映射器接口和XML文件**：创建一个用于操作用户数据的接口`UserMapper.java`，并在`src/main/resources/com/example/mapper`目录下创建映射器XML文件`UserMapper.xml`。
   ```java
   package com.example.mapper;
   import com.example.model.User;
   import java.util.List;
   public interface UserMapper {
       void insertUser(User user);
       User selectUser(int id);
       List<User> selectAll();
   }
   ```
   ```xml
   <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
   <mapper namespace="com.example.mapper.UserMapper">
       <resultMap id="BaseResultMap" type="com.example.model.User">
           <id column="id" property="id" jdbcType="BIGINT" />
           <result column="username" property="username" jdbcType="VARCHAR" />
           <result column="password" property="password" jdbcType="VARCHAR" />
       </resultMap>
       <select id="selectUserById" resultMap="BaseResultMap">
           SELECT * FROM user WHERE id = #{id}
       </select>
       <insert id="insertUser">
           INSERT INTO user (username, password) VALUES (#{username}, #{password})
       </insert>
   </mapper>
   ```

5. **使用Mapper**：在Service或Controller中使用UserMapper。
   ```java
   @Service
   public class UserService {
       @Autowired
       private UserMapper userMapper;
       public User getUserById(Long id) {
           return userMapper.selectUserById(id);
       }
       public void createUser(User user) {
           userMapper.insertUser(user);
       }
   }
   ```

通过这些步骤，你可以在Spring Boot项目中集成MyBatis，实现对数据库的访问和操作。