///   <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;

}