.NET截取指定长度汉字超出部分以"..."代替

///   <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;    
   }