spring boot整合mybatis代码

首先，需要在pom.xml文件中添加Mybatis和Mybatis-Spring的依赖：

<dependencies>
    <!-- Mybatis -->
    <dependency>
        <groupId>org.mybatis</groupId>
        <artifactId>mybatis</artifactId>
        <version>3.4.6</version>
    </dependency>

    <!-- Mybatis-Spring -->
    <dependency>
        <groupId>org.mybatis</groupId>
        <artifactId>mybatis-spring</artifactId>
        <version>1.3.1</version>
    </dependency>
</dependencies>

然后，配置Mybatis的SqlSessionFactory和MapperScannerConfigurer：

@Configuration
@MapperScan("com.example.demo.dao") // 扫描Mapper接口所在的包
public class MybatisConfig {

    @Autowired
    private DataSource dataSource;

    @Bean
    public SqlSessionFactory sqlSessionFactory() throws Exception {
        SqlSessionFactoryBean sessionFactory = new SqlSessionFactoryBean();
        sessionFactory.setDataSource(dataSource);
        sessionFactory.setTypeAliasesPackage("com.example.demo.entity"); // 设置实体类所在的包
        return sessionFactory.getObject();
    }

    @Bean
    public MapperScannerConfigurer mapperScannerConfigurer() {
        MapperScannerConfigurer scannerConfigurer = new MapperScannerConfigurer();
        scannerConfigurer.setBasePackage("com.example.demo.dao"); // 扫描Mapper接口所在的包
        return scannerConfigurer;
    }
}

其中，`@MapperScan`注解用于指定扫描Mapper接口所在的包，`SqlSessionFactory`用于创建SqlSession，`MapperScannerConfigurer`用于自动扫描Mapper接口并注册到Spring容器中。

最后，编写Mapper接口和Mapper映射文件：

public interface UserMapper {
    User selectById(Long id);
}

<mapper namespace="com.example.demo.dao.UserMapper">
    <select id="selectById" resultType="com.example.demo.entity.User">
        SELECT * FROM user WHERE id = #{id}
    </select>
</mapper>

这里以查询用户信息为例，使用`@Select`注解或者Mapper映射文件都可以实现。完整的代码可以参考下面的示例：

@RestController
public class UserController {

    @Autowired
    private UserMapper userMapper;

    @GetMapping("/user/{id}")
    public User getUserById(@PathVariable("id") Long id) {
        return userMapper.selectById(id);
    }
}

public interface UserMapper {
    User selectById(Long id);
}

<mapper namespace="com.example.demo.dao.UserMapper">
    <select id="selectById" resultType="com.example.demo.entity.User">
        SELECT * FROM user WHERE id = #{id}
    </select>
</mapper>