Android FTP tutorial

[Erel]

This tutorial covers the FTP object which is part of the Net library.
The Net library is based on Apache Commons Net.

Android OS doesn't allow us, the developers, to block the main thread for more than 5 seconds. When the main thread is busy for too long and is not able to handle the user events the "Application not responding" dialog appears.
Therefore slow operations like network operations should be done in the background.
The FTP library is built in such a way. All of the methods return immediately. When a task completes an event is raised. In fact you can submit several tasks one after another. The FTP protocol supports a single task at a time so the tasks will be processed serially.

Using the FTP library is pretty simple.
The first step is to initialize the FTP object. If this is an Activity module then you should do it in Activity_Create when FirstTime is true.
For Service modules it should be initialized in Service_Create.

Sub Process_Globals
    Dim FTP As FTP
End Sub
Sub Globals

End Sub

Sub Activity_Create(FirstTime As Boolean)
    If FirstTime Then
        FTP.Initialize("FTP", "ftp.example.com", 21, "user", "password")
    End If

FTP.Initialize doesn't connect to the server. Connection will be established implicitly together with the next task.

Download

Downloading a file is done by calling DownloadFile with the remote file path and the local file path.
If you want to show the download progress then you should handle DownloadProgress event.
When download completes the DownloadCompleted event is raised. The ServerPath is passed as the first parameter to all events. You can use it to distinguish between different tasks. Make sure to check the Success parameter. If Success is False then you can find the exception message by calling LastException.

    FTP.DownloadFile("/somefolder/files/1.zip", False, File.DirRootExternal, "1.zip")

Sub FTP_DownloadProgress (ServerPath As String, TotalDownloaded As Long, Total As Long)
Dim s As String
s = "Downloaded " & Round(TotalDownloaded / 1000) & "KB"
If Total > 0 Then s = s & " out of " & Round(Total / 1000) & "KB"
Log(s)
End Sub

Sub FTP_DownloadCompleted (ServerPath As String, Success As Boolean)
Log(ServerPath & ", Success=" & Success)
If Success = False Then Log(LastException.Message)
End Sub

Upload

Uploading is similar to downloading.

    FTP.UploadFile(File.DirRootExternal, "1.txt", True, "/somefolder/files/1.txt")

Sub FTP_UploadProgress (ServerPath As String, TotalUploaded As Long, Total As Long)
Dim s As String
s = "Uploaded " & Round(TotalUploaded / 1000) & "KB"
If Total > 0 Then s = s & " out of " & Round(Total / 1000) & "KB"
Log(s)
End Sub

Sub FTP_UploadCompleted (ServerPath As String, Success As Boolean)
Log(ServerPath & ", Success=" & Success)
If Success = False Then Log(LastException.Message)
End Sub

List files and folders

FTP.List sends a request for the list of files and folders in a specific path.
The ListCompleted event is raised when the data is available.
You can use code similar to the following code to get more information on the entries:

FTP.List("/")
...
Sub FTP_ListCompleted (ServerPath As String, Success As Boolean, Folders() As FTPEntry, Files() As FTPEntry)
    Log(ServerPath)
    If Success = False Then
        Log(LastException)
    Else
        For i = 0 To Folders.Length - 1
            Log(Folders(i).Name)
        Next
        For i = 0 To Files.Length - 1
            Log(Files(i).Name & ", " & Files(i).Size & ", " & DateTime.Date(Files(i).Timestamp))
        Next
    End If
End Sub

Delete
Delete is done by calling FTP.Delete with the full path. Again an event will be raised when the task completes (DeleteCompleted).

Closing the connection
You can close the connection by calling FTP.Close. Close will wait for the other tasks to complete and then will close the connection. This happens in the background.
FTP.CloseNow will immediately close the connection, failing the remaining tasks.

Some notes:
- At any given time there should be less than 15 waiting tasks. Otherwise you will get a RejectedExecutionException (this happens when the internal threads pool is exhausted).
- The order of the completed tasks may be different than the order of submission.
- The AsciiFile parameters sets the file transfer mode. If AsciiFile is true then every occurrence of an end of line character will be translated based on the server native end of line character. If your FTP server is Unix or Linux then the end of line character is the same as Android.
In most cases you can set AsciiFile to false.

The library is available for download here: http://www.basic4ppc.com/forum/addit...smtp-pop3.html

[carlosmdg]

I need an example file please!

I copy the indications but dont work me

[Erel]

What error do you get?

[AscySoft]

Does this library knows sftp protocol? Sorry, this is my first day with android/b4a

[Erel]

No, only FTP is supported.

[AscySoft]

Then I must encode/zip files manually for strong security reason then upload them using ftp! Coud you point to a solution/link that sound anything like that? I mean, zip with password/encode files etc

[carlosmdg]

Originally Posted by Erel

What error do you get?

I'd like to sync through ftp but not responding.
The code i have is the following:

Sub Process_Globals
...
    Dim FTP As FTP
End Sub

Sub Activity_Create(FirstTime As Boolean)
    Activity.AddMenuItem2("Sincronizar","update2",LoadBitmap(File.DirAssets,"refresh.png"))
    If FirstTime Then
        FTP.Initialize("FTP", "ftp.xxx", 21, "user", "pass")
    End If
End Sub

Sub Update2_click
    sdRoot = File.DirDefaultExternal & "/"
    FTP.DownloadFile("/Team/prestadores.txt", False, sdRoot, "PRESTADORESFTP.txt")
    FTP.UploadFile(sdRoot,"Reg" & d.GetDeviceId  & ".txt", True, "/Team/RegTmp" & d.GetDeviceId  & ".txt")
End Sub

when in using debug mode, i see this:

DownloadService [donesuccessfully=false, hc=anywheresoftware.b4a.http.HttpClientWrapper@44d029d0, jobstatus=0 , notification=1(Notification) Not initialized, status_done=2, status_none=0, status_working=1, target=(OutputStream) Not initialized, url=

I test the apk in my dispositive but dont work

[Erel]

The DownloadService is not related. It is a code module that you have added to your project.

Have you added the FTP_DownloadCompleted / FTP_UploadCompleted subs? Without them you will not see any result.

[carlosmdg]

Originally Posted by Erel

The DownloadService is not related. It is a code module that you have added to your project.

Have you added the FTP_DownloadCompleted / FTP_UploadCompleted subs? Without them you will not see any result.

I have a Service module called DownloadService, it's the same like the example http://www.basic4ppc.com/forum/basic...#post43109

And I have this subs...

Sub FTP_DownloadProgress (ServerPath As String, TotalDownloaded As Long, Total As Long)
    Dim s As String
    s = "Downloaded " & Round(TotalDownloaded / 1000) & "KB"
    If Total > 0 Then s = s & " out of " & Round(Total / 1000) & "KB"
    Log(s)
End Sub

Sub FTP_DownloadCompleted (ServerPath As String, Success As Boolean)
    Log(ServerPath & ", Success=" & Success)
    If Success = False Then Log(LastException.Message)
End Sub

Sub FTP_UploadProgress (ServerPath As String, TotalUploaded As Long, Total As Long)
    Dim s As String
    s = "Uploaded " & Round(TotalUploaded / 1000) & "KB"
    If Total > 0 Then s = s & " out of " & Round(Total / 1000) & "KB"
    Log(s)
End Sub

Sub FTP_UploadCompleted (ServerPath As String, Success As Boolean)
    Log(ServerPath & ", Success=" & Success)
    If Success = False Then Log(LastException.Message)
End Sub

When i run the project step by step, never calls to DownloadService module

[Erel]

Try to create a simple project which downloads a single file and see if it works. Make sure to check the logs (including the unfiltered logs if you don't see any message).