mybatis long 类型返回为null报异常

解决MyBatis Mapper返回空异常

最新推荐文章于 2025-04-07 14:03:29 发布

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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。

 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