将指定字符串按指定长度进行剪切

 ///   <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;        }