mybatis long 类型返回为null报异常

最新推荐文章于 2025-06-10 12:19:00 发布

原创最新推荐文章于 2025-06-10 12:19:00 发布 · 5.5k 阅读

3 ·

CC 4.0 BY-SA版权

文章标签：

#mybatis

ssm 专栏收录该内容

20 篇文章

订阅专栏

本文详细解析了在使用MyBatis框架时，Mapper方法返回null导致的异常问题，尤其是在处理long型原始数据类型时。通过使用IFNULL函数，有效避免了因数据缺失而引发的运行时错误，确保了应用程序的稳定性和健壮性。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

 Mapper method 'com.mpn.dao.TWeatherMapper.avgWeatherTemperature attempted to return null from a method with a primitive return type (long).

  <select id="avgWeatherTemperature" resultType="java.lang.Long" parameterType="java.lang.String" >
        SELECT IFNULL(AVG(WeatherTemperature),0) AS OrderAverage FROM t_weather WHERE WeatherDate= #{date,jdbcType=VARCHAR};
  </select>
  
   <select id="sumWeatherRainfall" resultType="java.lang.Long" parameterType="java.lang.String" >
        SELECT SUM(WeatherTemperature) AS OrderAverage FROM t_weather WHERE WeatherDate= #{date,jdbcType=VARCHAR};
  
  </select>
  
   <select id="avghumidity" resultType="java.lang.Long" parameterType="java.lang.String" >
        SELECT IFNULL(AVG(WeatherHumidity),0) AS OrderAverage FROM t_weather WHERE WeatherDate= #{date,jdbcType=VARCHAR};
  </select>

由于返回为空long中没有此类型所以抛异常，改为

 <!-- 根据日期来进行计算平局值与 -->
   <select id="avgWeatherTemperature" resultType="java.lang.Long" parameterType="java.lang.String" >
        SELECT IFNULL(AVG(WeatherTemperature),0) AS OrderAverage FROM t_weather WHERE WeatherDate= #{date,jdbcType=VARCHAR};
  </select>
  
   <select id="sumWeatherRainfall" resultType="java.lang.Long" parameterType="java.lang.String" >
        SELECT IFNULL(SUM(WeatherTemperature),0) AS OrderAverage FROM t_weather WHERE WeatherDate= #{date,jdbcType=VARCHAR};
  
  </select>
  
   <select id="avghumidity" resultType="java.lang.Long" parameterType="java.lang.String" >
        SELECT IFNULL(AVG(WeatherHumidity),0) AS OrderAverage FROM t_weather WHERE WeatherDate= #{date,jdbcType=VARCHAR};
  </select>

用IFNULL来进行判断