解决实体类属性字段和数据库字段不一致的问题

解决实体类属性字段和数据库字段不一致的问题

一、起别名

查询sql语句时给字段起别名，别名和实体类属性字段一致

<select id="getUserList" resultType="User">
    select USER_ID as id,USER_NAME as name,USER_PASSWORD as password from user2 where USER_ID = #{id};
</select>

二、resultMap

使用mybatis配置文件中配置resultMap进行字段映射

<resultMap id="xxx" type="com.mybatis.domain.User">
    <id property="id" column="ID"></id>
    <result property="userName" column="USER_NAME"></result>
    <result property="password" column="PASSWORD"></result>
    <result property="userInformation" column="USER_INFORMATION"></result>
</resultMap>

使用@Result()和@ResultMap()注解
@Results()注解类似<resultMap id="resultField"></resultMap>
@ResultMap()可以让多个接口使用@Result()中的字段映射，注意@Result注解id和ResultMap注解中的value值一致

@Select({"select * from sys_user"})
@Results(id="userMap", value={
			@Result(column="id", property="id", id=true),
		    @Result(column="user_name", property="userName"),
		    @Result(column="user_password ", property="userPassword"),
		    @Result(column="user_email", property="userEmail"),
		    @Result(column="user_info", property="userInfo"),
		    @Result(column="head_img", property="headImg", jdbcType=JdbcType.BLOB),
		    @Result(column="create_time", property="createTime", jdbcType=JdbcType.TIMESTAMP)
	})
List<User> queryUserList();

@ResultMap()注解类似<select id="queryUserList" resultMap="resultField"></select> // 使用暂时失败

@Select({"select id,user_name,user_password,user_email,user_info,head_img,create_time from sys_user where id = #{id}"})
	@Results(id="userMap", value={
			@Result(column="id", property="id", id=true),
		    @Result(column="user_name", property="userName"),
		    @Result(column="user_password ", property="userPassword"),
		    @Result(column="user_email", property="userEmail"),
		    @Result(column="user_info", property="userInfo"),
		    @Result(column="head_img", property="headImg", jdbcType=JdbcType.BLOB),
		    @Result(column="create_time", property="createTime", jdbcType=JdbcType.TIMESTAMP)
	})
User selectUserById(Long id);
	
@Select({"select * from sys_user"})
@ResultMap("userMap")
List<User> queryUserList();

三、驼峰式命名

根据数据库字段名的下划线实体类属性字段进行驼峰式命名

配置文件中开启驼峰转换
yml配置

mybatis:
  configuration:
    map-underscore-to-camel-case: true #开启数据库字段驼峰转换

mybatis配置

<configuration>
<!--设置启用数据库字段下划线映射到java对象的驼峰式命名属性，默认为false--> 
    <settings>
        <setting name="mapUnderscoreToCamelCase" value="true"/>
    </settings>
</configuration>