B4J Tutorial AsyncStreamsObject - Send and receive objects over the network

Erel · Nov 18, 2013

For new projects it is recommended to use B4XSerializator instead of this solution.

AsyncStreamsObject allows you to send and receive objects instead of bytes.
You can read more about it here: http://www.b4x.com/android/forum/th...d-and-receive-objects-instead-of-bytes.30543/

This example connects to the same Android example and allows you to communicate with the device.
The device app acts as the server as the desktop firewalls usually blocks incoming connections.

You can download the Android example here: http://www.b4x.com/android/forum/th...e-objects-instead-of-bytes.30543/#post-202288
Make sure to update B4A RandomAccessFile library to v1.6: http://www.b4x.com/android/forum/th...handle-streams-of-any-size.30494/#post-177051

Once you have a valid connection it is very simple to send and receive custom types, drawings, collections and files.

Douglas Farias · Dec 15, 2014

Ok, but AStreamO_NewObject on the b4a dont save the file, only give logs.

1° i m sending the key file:myfilename from b4j its correct now

2° on the b4a i m get this in AStreamO_NewObject with substring , this is ok

B4X:

Sub astreamO_NewObject(Key As String, Value As Object)
    If Key.StartsWith("arquivo:") Then
    Log(Key.SubString(8))
            Dim fileName As String = Value
            Log(fileName)
            Log("Received file. File size: " & File.Size(astreamO.TempFolder, fileName))
  End If
   
End Sub

but the problem is how to write a file with this name now, the astreamO_NewObject dont save the file, i think this code is in your class on b4a.
i m sending the correct name, i m geting this correct name on b4a, and now how to save the file with correct name?

Douglas Farias · Dec 15, 2014

done, i have made this

B4X:

    If Key.StartsWith("arquivo:") Then
    Log(Key.SubString(8))
            Dim fileName As String = Value
            File.Copy(astreamO.TempFolder,fileName, fp , Key.SubString(8))
            Log(File.ListFiles(fp))
    End If

ty @Erel

Douglas Farias · Dec 17, 2014

@Erel
when i use this code, with big files, i have a small bug

B4X:

If Key.StartsWith("arquivo:") Then
            Dim fileName As String = Value
            log("aqui")
            File.Copy(astreamO.TempFolder,fileName, fp , Key.SubString(8))
            Log("done")
    End If

for exemple, send from pc a video with 60mb, on the b4a it make a laggg when make this File.Copy
i see the log "aqui" like the code. log("aqui")

my app stop respose for 5 or 10 seconds, i have try make this

B4X:

If Key.StartsWith("arquivo:") Then
            Dim fileName As String = Value
            log("aqui")
            ProgressDialogShow2("carregando...", False)
            DoEvents
            File.Copy(astreamO.TempFolder,fileName, fp , Key.SubString(8))
            Log("done")
    End If

but dont work with doevents, my app stop response too with

B4X:

ProgressDialogShow2("carregando...", False)
         DoEvents

and i dont see the ProgressDialogShow2 only the log "aqui"

and later my app stop work for 5 - 10 seconds i see "Done" the last log.

now the question, why this? i m know the file is bigger 60mb, but have a way to my app dont stop work when make a file.copy?
and how can i add a progress on this? ProgressDialogShow2("Copying...", False), later done ProgressDialogHide

Erel · Dec 18, 2014

The problem is that File.Copy is running on the main thread.

You can use the Threading library to create a sub that will copy the file with a background thread.

Douglas Farias · Dec 18, 2014

why use a library to make a sub? can u give a simple example code?

callsubcopy(folders, file)

sub copy
file.copy
end sub

Erel · Dec 18, 2014

You need to use the Threading library. You will not be able to run it with the background without it.

The Threading library is explained here: https://www.b4x.com/android/help/threading.html

Douglas Farias · Dec 19, 2014

this dont helped my @Erel
look i made this

B4X:

        'VIDEOS
        Else If Key.SubString(8).StartsWith("videos:") Then
        Dim fileName As String = Value
        File.MakeDir(fp, "Videos")
        pasta = File.Combine(fp, "Videos")
        ProgressDialogShow2("carregando...", False)
        Private l As List
        l.Initialize
        l.AddAll(Array As String(astreamO.TempFolder, fileName, pasta, Key.SubString(15)))
        TR.RunOnGuiThread("copiar_arquivos" , Array As Object(l))


Sub copiar_arquivos(MapObj As Object)
Private l As List
l.Initialize
l = MapObj
File.Copy(l.Get(0), l.Get(1), l.Get(2), l.Get(3))
ProgressDialogHide
End Sub

but my app stop work too with RunOnGuiThread.
only with big sizes the app stop works, 60mb+

EDIT: 03:06

B4X:

        'VIDEOS
        Else If Key.SubString(8).StartsWith("videos:") Then
        Dim fileName As String = Value
        File.MakeDir(fp, "Videos")
        pasta = File.Combine(fp, "Videos")
        Private l As List
        l.Initialize
        ProgressDialogHide
        ProgressDialogShow2("Copiando...", False)
        l.AddAll(Array As String(astreamO.TempFolder, fileName, pasta, Key.SubString(15)))
        TR.Start(Me, "copiar_arquivos" , Array As Object(l))

this code works, with tr.start

thx erel

Erel · Dec 19, 2014

You don't need to call RunOnGuiThread. You need to call Start: https://www.b4x.com/android/help/threading.html#thread_start

YIM bunchhat · Aug 11, 2015

I cannot send file and receive file. How to send file from phone to pc? Ex: file .pdf in sd card...... Could you write me simple code that work only send file from phone to PC? your example is complicated for me.......now I am really headache...

Erel · Aug 11, 2015

You will need to go over the code and learn it. Sending the file is relatively simple as it just uses WriteStream to send the file.

B4J Tutorial AsyncStreamsObject - Send and receive objects over the network

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