在C#中如何判断FTP服务器是否存在？

直接使用FTPWebRequest类：

var request = (FtpWebRequest)WebRequest.Create(”ftp://ipaddress//dir");request.Credentials = new NetworkCredential("user", "pass");request.Method = WebRequestMethods.Ftp.GetFileSize; try{ FtpWebResponse response = (FtpWebResponse)request.GetResponse();}catch (WebException ex){ FtpWebResponse response = (FtpWebResponse)ex.Response; if (response.StatusCode == FtpStatusCode.ActionNotTakenFileUnavailable) { //不存在 }}