///   <summary>   
///   將指定字串按指定長度進行剪下，   
///   </summary>   
///   <param   name= "Str "> 需要截斷的字串 </param>   
///   <param   name= "maxLength "> 字串的最大長度 </param>   
///   <param   name= "endWith "> 超過長度的字尾 </param>   
///   <returns> 如果超過長度，返回截斷後的新字串加上字尾，否則，返回原字串 </returns>   
public static string StringTruncat(string Str, int maxLength, string endWith)
{
    if (string.IsNullOrEmpty(Str))
    {
        return Str + endWith;
    }
    if (maxLength < 1)
    {
        return Str;
    }
    if (Str.Length > maxLength)
    {
        string strTmp = Str.Substring(0, maxLength);
        if (string.IsNullOrEmpty(endWith))
            return strTmp;
        else
            return strTmp + endWith;
    }
    return Str;
}