截取字符串显示

///   <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;
}