VB.NET测试FTP连接

Question

所以我想上传文件到我的FTP，虽然我想要它来测试FTP的细节是否正确。我发现下面的代码，虽然它的工作原理虽然它显示'存在'当它连接，但是当它无法连接[与假的细节]它不会做任何事情（我想要一个错误显示说它不能连接）

Imports System.Net 

    Dim request = _ 
    DirectCast(WebRequest.Create _ 
    ("ftp://ftp.example.com/folder_here/"), FtpWebRequest) 

    request.Credentials = _ 
    New NetworkCredential("user_here", "pass_here") 

    request.Method = WebRequestMethods.Ftp.ListDirectory 

    Try 
     Using response As FtpWebResponse = _ 
     DirectCast(request.GetResponse(), FtpWebResponse) 
      ' Folder exists here 
      MsgBox("exists!") 
     End Using 

    Catch ex As WebException 
     Dim response As FtpWebResponse = _ 
     DirectCast(ex.Response, FtpWebResponse) 
     'Does not exist 
     If response.StatusCode = _ 
     FtpStatusCode.ActionNotTakenFileUnavailable Then 
      MsgBox("Doesn't exist!") 
     End If 
    End Try 

我该如何解决这个问题？

Answer 1

我认为使用块可能会捕捉异常。试试这个代替

Try 
    Dim response As FtpWebResponse = _ 
    DirectCast(request.GetResponse(), FtpWebResponse) 
     ' Folder exists here 
    MsgBox("exists!") 

Catch ex As WebException 
    Dim response As FtpWebResponse = _ 
    DirectCast(ex.Response, FtpWebResponse) 
    'Does not exist 
    If response.StatusCode = _ 
    FtpStatusCode.ActionNotTakenFileUnavailable Then 
     MsgBox("Doesn't exist!") 
    End If 
End Try