如何检查FTP连接?

你可以试着用 System.Net.FtpWebRequest 然后检查一下 GetResponseStream 方法。

比如说

System.Net.FtpWebRequest myFTP = new System.Net.FtpWebRequest

//Add your credentials and ports

try
{
    myFTP.GetResponseStream();
   //set some flags
}
catch ex
{
  //handle it when it is not working
}

尝试以下操作:

FtpWebRequest requestDir = (FtpWebRequest)FtpWebRequest.Create("ftp://ftp.google.com");
requestDir.Credentials = new NetworkCredential("username", "password");
try
{
     WebResponse response = requestDir.GetResponse();
     //set your flag
}
catch
{
}

这是我使用的方法,如果你知道更好的方法,请告诉我。

/*你好 这是一种实用的方法 Ubirajara 100%墨西哥 */

private bool isValidConnection(string url, string user, string password)
{
    try
    {
        FtpWebRequest request = (FtpWebRequest)WebRequest.Create(url);
        request.Method = WebRequestMethods.Ftp.ListDirectory;
        request.Credentials = new NetworkCredential(user, password);
        request.GetResponse();
    }
    catch(WebException ex)
    {
        return false;
    }
    return true;
}

  public async Task<bool> ConnectAsync(string host, string user, string password)
    {
        try
        {
            FtpWebRequest request = (FtpWebRequest)WebRequest.Create(host);
            request.Credentials = new NetworkCredential(user, password);
            request.UseBinary = true;
            request.UsePassive = true;
            request.KeepAlive = false; // useful when only to check the connection.
            request.Method = WebRequestMethods.Ftp.ListDirectory;
            FtpWebResponse response = (FtpWebResponse) await request.GetResponseAsync();
            return true;
        }
        catch (Exception)
        {
            return false;
        }            
    }

使用其中一个 System.Net.FtpWebRequest 或 System.Net.WebRequestMethods.Ftp

这是从msdn站点到diplay服务器的文件

public static bool DisplayFileFromServer(Uri serverUri)
{
// The serverUri parameter should start with the ftp:// scheme. 
if (serverUri.Scheme != Uri.UriSchemeFtp)
{
    return false;
}
// Get the object used to communicate with the server.
WebClient request = new WebClient();

// This example assumes the FTP site uses anonymous logon.
request.Credentials = new NetworkCredential ("anonymous","janeDoe@contoso.com");
try 
{
    byte [] newFileData = request.DownloadData (serverUri.ToString());
    string fileString = System.Text.Encoding.UTF8.GetString(newFileData);
    Console.WriteLine(fileString);
}
catch (WebException e)
{
    Console.WriteLine(e.ToString());
}
return true;
}