///   <summary>     ///   将指定字符串按指定长度进行剪切，     ///   </summary>     ///   <param   name= "oldStr "> 需要截断的字符串 </param>     ///   <param   name= "maxLength "> 字符串的最大长度 </param>     ///   <param   name= "endWith "> 超过长度的后缀 </param>     ///   <returns> 如果超过长度，返回截断后的新字符串加上后缀，否则，返回原字符串 </returns>     public static string StringTruncat(string oldStr, int maxLength, string endWith)     {         if (string.IsNullOrEmpty(oldStr))             //   throw   new   NullReferenceException( "原字符串不能为空 ");             return oldStr + endWith;         if (maxLength < 1)             throw new Exception("返回的字符串长度必须大于[0] ");         if (oldStr.Length > maxLength)         {             string strTmp = oldStr.Substring(0, maxLength);             if (string.IsNullOrEmpty(endWith))                 return strTmp;             else                 return strTmp + endWith;         }         return oldStr;     }