Android Tutorial FileTransfer - Send and receive files with AsyncStreams

tdocs2 · Oct 19, 2014

The code in the link of Post #59 in this thread (courtesy of Erel) works perfectly.

I changed the FileTransfer to display the IP address of the WiFi connection and show who initiated the connection - Client, initiator and Host.

Code follows:

Client Side

B4X:

Public Sub ConnectWifi(IP As String)
    'added by me to change display label as to who I am connecting"
    HostIP=IP 'added HostIP to Process Globals
    socket1.Initialize("socket1")
    socket1.Connect(IP, port, 30000)
    WifiStatus = "Trying to connect..."
    UpdateUI
End Sub

Private Sub socket1_Connected (Successful AsBoolean)
'client connected to server
If Successful Then
WifiConnected = True
StartAStream(socket1.InputStream, socket1.OutputStream)
WifiStatus = "Client - Connected to " & HostIP
Else
WifiStatus = "Error: " & LastException
EndIf
UpdateUI
End Sub

Server Side

B4X:

Private Sub server_NewConnection (Successful As Boolean, NewSocket As Socket)
    'server accepted client
    If Successful Then
      'this code just added to get IP address of the sender
        Dim r As Reflector
        r.Target = NewSocket
        r.Target = r.GetField("socket")
        r.Target = r.RunMethod("getInetAddress") 'InetAddress
        Dim senderip As String = r.RunMethod("getHostAddress") 'it gets sender or client IP
      'end this code just added to get IP address of the sender
        WifiConnected = True
        StartAStream(NewSocket.InputStream, NewSocket.OutputStream)
        WifiStatus = "Host - Connected with " & senderip
    Else
        WifiStatus = "Error: " & LastException
    End If
    UpdateUI
    server.Listen
End Sub

It seems a bit paradoxical that r.RunMethod("getHostAddress") actually gets sender or client IP, but it does.

Thanks again, Erel.

Sandy

tdocs2 · Oct 20, 2014

Greetings, all.

Thank you for your patience and generosity in answering my questions....

I repeat that FileTransfer stretches my tech skills - no experience in Network or AsyncStreams, but I will keep chipping at it...

1. Three tablets A, B, and C. A is the "server". B and C are the clients.
2. Run File Transfer on all 3 tablets.
3. Connect B to A. Success.
4. Connect C to A.
5. B is disconnected. Great!

Where in the FileTransfer Service does step 5 take place?
- In tablet A, Sub server_NewConnection.
- In tablet B, where and what does tablet A tell tablet B for tablet B to know it has been or is disconnected?

Best regards.

Sandy

Erel · Oct 20, 2014

Change StartAStream to check whether astream is already initialized. If yes then close it first.

tdocs2 · Oct 20, 2014

Thank you, Erel.

I may not want to close it if ReceivingFile = True.

How do I reject the new connection with something like "busy... Try again."?

Best regards.

Sandy

Erel · Oct 20, 2014

You can immediately close the new socket.

tdocs2 · Oct 20, 2014

Erel said:
You can immediately close the new socket.

Thank you again, Erel

Included Close newsocket in server_NewConnection (see code below).

Tested as follows:
1. 3 tablets, A, B, C. A is "server"
2. Connected B to A. Success
3. Connected C to A. B disconnected automatically. Success
4. Connected B to A. C disconnected automatically. Success
5. Sent file from B to A. Success
6. Connected C to A. B disconnected automatically. Success
7. Sent large file from C to A. File started to send.
9. Connected B to A while C was transmitting to A.
10. ERROR in A and activity terminated.

server_NewConnection code and Error log from Tablet A (server) follows:

server_NewConnection code

B4X:

Private Sub server_NewConnection (Successful As Boolean, NewSocket As Socket)
'added by me to prevent disconnect on ongoing file transfer
    Log("server_NewConnection")
    If ReceivingFile = True Then
        NewSocket.Close
    Log("ReceivingFile "& ReceivingFile)
        'Return - if Return is left - both B and C stay connected
    End If 

    'server accepted client
    If Successful Then
      'this code just added to get IP address of the sender
        Dim r As Reflector
        r.Target = NewSocket
           r.Target = r.GetField("socket")
           r.Target = r.RunMethod("getInetAddress") 'InetAddress
           Dim senderip As String = r.RunMethod("getHostAddress") 'it gets sender or client IP
      'end this code just added to get IP address of the sender
        WifiConnected = True
        StartAStream(NewSocket.InputStream, NewSocket.OutputStream)
        WifiStatus = "Host - Connected with " & senderip
    Else
        WifiStatus = "Error: " & LastException
    End If
    UpdateUI
    server.Listen
End Sub

Error log from Tablet A (server)

B4X:

** Activity (main) Create, isFirst = true **
** Activity (main) Resume **
** Service (filetranser) Create **
** Service (filetranser) Start **
server_NewConnection
StartAStream
ReceivingFile false
server_NewConnection
StartAStream
ReceivingFile false
1 /storage/emulated/0/Android/data/b4a.example.filetransfer/files*7
2 /storage/emulated/0/Android/data/b4a.example.filetransfer/files*7
3 /storage/emulated/0/Android/data/b4a.example.filetransfer/files*book1.xls
server_NewConnection
StartAStream
ReceivingFile false
1 /storage/emulated/0/Android/data/b4a.example.filetransfer/files*7
2 /storage/emulated/0/Android/data/b4a.example.filetransfer/files*7
3 /storage/emulated/0/Android/data/b4a.example.filetransfer/files*1.txt
server_NewConnection
StartAStream
ReceivingFile false
server_NewConnection
ReceivingFile true


java.lang.NullPointerException
    at anywheresoftware.b4a.agraham.reflection.Reflection.runmethod(Reflection.java:205)
    at anywheresoftware.b4a.agraham.reflection.Reflection.RunMethod(Reflection.java:802)
    at b4a.example.filetransfer.filetranser._server_newconnection(filetranser.java:372)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:511)
    at anywheresoftware.b4a.BA.raiseEvent2(BA.java:175)
    at anywheresoftware.b4a.BA$3.run(BA.java:320)
    at android.os.Handler.handleCallback(Handler.java:725)
    at android.os.Handler.dispatchMessage(Handler.java:92)
    at android.os.Looper.loop(Looper.java:137)
    at android.app.ActivityThread.main(ActivityThread.java:5039)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:511)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
    at dalvik.system.NativeStart.main(Native Method)
java.lang.RuntimeException: java.lang.NullPointerException


    at anywheresoftware.b4a.BA.raiseEvent2(BA.java:201)
    at anywheresoftware.b4a.BA$3.run(BA.java:320)
    at android.os.Handler.handleCallback(Handler.java:725)
    at android.os.Handler.dispatchMessage(Handler.java:92)
    at android.os.Looper.loop(Looper.java:137)
    at android.app.ActivityThread.main(ActivityThread.java:5039)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:511)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
    at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
    at anywheresoftware.b4a.agraham.reflection.Reflection.runmethod(Reflection.java:205)
    at anywheresoftware.b4a.agraham.reflection.Reflection.RunMethod(Reflection.java:802)
    at b4a.example.filetransfer.filetranser._server_newconnection(filetranser.java:372)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:511)
    at anywheresoftware.b4a.BA.raiseEvent2(BA.java:175)
    ... 10 more

Any help or guidance truly welcomed.

Sandy

tdocs2 · Oct 20, 2014

Shalom, Erel.

From Post 62 from me, I will keep chipping at it...

I changed the server_NewConnection Sub (see below), and it seems to work with 3 tablets (see Test steps from post # 66). I do not want to dilute myself in thinking that this is the solution, but if you could give it the onceover and let me know. The invitation extends to any and all.

server_NewConnection code

B4X:

Private Sub server_NewConnection (Successful As Boolean, NewSocket As Socket)
'added by me to prevent disconnect on ongoing file transfer
    Log("server_NewConnection")
    If ReceivingFile = True OR SendingFile = True Then
        NewSocket.Close
        Log("ReceivingFile "& ReceivingFile)
    End If

Try
    'server accepted client
    If Successful Then
      'this code just added to get IP address of the sender
        Dim r As Reflector
        r.Target = NewSocket
           r.Target = r.GetField("socket")
           r.Target = r.RunMethod("getInetAddress") 'InetAddress
           Dim senderip As String = r.RunMethod("getHostAddress") 'it gets sender or client IP
      'end this code just added to get IP address of the sender
        WifiConnected = True
        StartAStream(NewSocket.InputStream, NewSocket.OutputStream)
        WifiStatus = "Host - Connected with " & senderip
    Else
        WifiStatus = "Error: " & LastException
    End If
    UpdateUI
    server.Listen
Catch
    Log ("LastException "&LastException)
End Try
    server.Listen 'added to restart listening - OK if twice

End Sub

Thank you.

Sandy

Erel · Oct 21, 2014

Looks fine to me.

tdocs2 · Oct 21, 2014

Thank you, Erel.

Douglas Farias · Nov 19, 2014

here the file is saved on the pc? i have file sent complet on my device but i dont find this on the pc *-*

Erel · Nov 19, 2014

Are you using the C# example? You should instead use the B4J example which is better and will give you more control:
http://www.b4x.com/android/forum/th...r-b4j-server-over-the-internet.37201/#content

Or:
http://www.b4x.com/android/forum/threads/34612/#content

Douglas Farias · Nov 19, 2014

lol i dont see the last i go try to use
i and my friend make a new changes on the c# example

form1.cs

B4X:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Net;
using System.Net.Sockets;
using System.Threading;
using System.IO;
using ICSharpCode.SharpZipLib.Checksums;

namespace FileTransfer
{
    public partial class Form1 : Form
    {
        private Thread connector;
        private TcpClient client;
        private volatile NetworkStream stream;
        private IPAddress ip;
        private volatile bool connectorRunning;
        private readonly int port = 21341;
        private readonly int STREAM_PREFIX = -2;
        private string fileToSend;
        public Form1()
        {
            InitializeComponent();
          
        }
        private void Form1_Load(object sender, EventArgs e)
        {
            SetStatus(false);
        }

        private void btnConnect_Click(object sender, EventArgs e)
        {
            if (connectorRunning)
            {
                log("O conector já esta em uso!.");
                return;
            }
            try
            {
                ip = IPAddress.Parse(txtIP.Text);
            }
            catch (Exception ee)
            {
                log(ee.Message);
            }
            connectorRunning = true;
            connector = new Thread(startConnection);
            connector.Name = "Conector";
            //connector.IsBackground = true;
            connector.Start();
        }
        private void SetStatus(bool connected)
        {
            MethodInvoker mi = delegate()
            {
                btnSend.Enabled = connected;
                btnConnect.Enabled = !connected;
                lblStatus.Text = connected ? "Conectado" : "Disconectado";
            };
            this.BeginInvoke(mi);
        }
        private void log(string msg)
        {
            MethodInvoker mi = delegate()
            {
                txtLogs.AppendText(msg);
                txtLogs.AppendText("\r\n");
                txtLogs.SelectionStart = txtLogs.Text.Length;
                txtLogs.ScrollToCaret();
            };
            if (this.InvokeRequired)
                this.BeginInvoke(mi);
            else
                mi.Invoke();
        }
      
        private void startConnection()
        {
            try
            {
                client = new TcpClient();
                client.Connect(ip, port);
                log("Connected!");
                SetStatus(true);
                stream = client.GetStream();
                BinaryReader br = new BinaryReader(stream);
                string fileName = "";
                while (connectorRunning)
                {                  
                    string prefix = br.ReadString();
                    if(prefix.Length  > 0)
                    {
                        log(string.Format("Prefixo recebido >> {0} - {1}", prefix, prefix.Length));
                    if (prefix == "SFF") //regular message
                    {
                        while((fileName = br.ReadString()).Length == 0 && fileName.Replace(" ", "").Length == 0);
                        log("Receiving: " + fileName);
                        fileName = System.IO.Path.Combine(Environment.CurrentDirectory, fileName);
                   }
                    else if (prefix == "SFD") //stream message
                    {
                        string SizeStr;
                        while((SizeStr = br.ReadString()).Length == 0 && SizeStr.Replace(" ", "").Length == 0);
                        int Size = int.Parse(SizeStr);
                        log(string.Format("Tamanho recebido: {0}", Size));
                        long length = br.ReadInt64(); //total stream length
                        log(string.Format("Inicializando download ({0})..", length));
                        Adler32 adler = new Adler32();
                        // using (FileStream fs = new FileStream(fileName, FileMode.Create)) //isso n tem a ver? n
                        if(File.Exists(fileName))
                            File.Delete(fileName);
                        using (FileStream fs = new FileStream(fileName, FileMode.OpenOrCreate))
                        {
                            log(string.Format("Recebendo arquivo \"{0}\"!", fileName));
                            int total = 0;
                            int received = 0;
                            byte[] buffer = new byte[Size - total < 1024 ? Size - total : 1024];
                            while ((total += (received = stream.Read(buffer, 0, buffer.Length))) < Size)
                            {
                                this.Text = string.Format("Total: {0} - {1} => {2}", total, received, buffer.Length);
                                fs.Write(buffer, 0, received);
                                adler.Update(buffer, 0, received);
                            }
                            log("Fim!");
                        }
                        long checkSum = br.ReadInt64();
                        log(string.Format("Verifique o sol: {0} => {1}", checkSum, adler.Value));
                        if (checkSum != adler.Value)
                        {
                            throw new Exception("Checksum does not match.");
                        }
                        log("File received successfully.");
                    }
                    else
                    {
                        throw new Exception("Unexpected value: " + prefix);
                    }
                }
                }
                log("End of the connection");
            }
            catch (Exception e)
            {
                log(e.Message);
                log(e.StackTrace);
                SetStatus(false);
                connectorRunning = false;
            }
        }

        protected override void OnClosing(CancelEventArgs e)
        {
            System.Diagnostics.Process.GetCurrentProcess().Kill();
        }
      
        private void btnSend_Click(object sender, EventArgs e)
        {
            if (openFileDialog1.ShowDialog(this) == DialogResult.OK)
            {
                btnSend.Enabled = false;
                fileToSend = openFileDialog1.FileName;
                Thread sendThread = new Thread(sendFile);
                sendThread.Name = "SendThread";
                sendThread.IsBackground = true;
                sendThread.Start();
            }
        }
        private void sendFile()
        {
            try
            {
                Adler32 adler = new Adler32();
                log("Sending: " + fileToSend);
                using (FileStream fs = new FileStream(fileToSend, FileMode.Open))
                {
                    byte[] name = Encoding.UTF8.GetBytes(Path.GetFileName(fileToSend));
                    BinaryWriter bw = new BinaryWriter(stream);
                    //send the first message which is the file name
                    bw.Write(name.Length);
                    bw.Write(name);
                    //send the stream message
                    bw.Write(STREAM_PREFIX);
                    long size = new FileInfo(fileToSend).Length;
                    bw.Write(size);
                    long written = 0;
                    byte[] buffer = new byte[8192];
                    while (written < size)
                    {
                        int count = fs.Read(buffer, 0, Math.Min((int)(size - written), buffer.Length));
                        stream.Write(buffer, 0, count);
                        adler.Update(buffer, 0, count);
                        written += count;
                    }
                    bw.Write(adler.Value);
                    log("File sent successfully.");
                }
            }
            catch (Exception e)
            {
                log(e.Message);
            }
            MethodInvoker mi = delegate()
            {
                btnSend.Enabled = !btnConnect.Enabled;
            };
            this.BeginInvoke(mi);
        }


    }
}

and on the file transfer we made,

B4X:

Public Sub SendFile(Dir As String, FileName As String)
Private bConverter As ByteConverter
Private www As String
    Dim totalSizeForSending As Long = File.Size(Dir, FileName)
    Dim In As InputStream = File.OpenInput(Dir, FileName)
    countingStream.Initialize(In)
    currentFile = FileName.SubString(FileName.LastIndexOf("/") + 1)
    astream.Write("SFF".GetBytes("UTF8"))
    astream.Write(currentFile.GetBytes("UTF8"))
    astream.Write("SFD".GetBytes("UTF8"))
    www = totalSizeForSending
    astream.Write(www.GetBytes("UTF8"))
    astream.WriteStream(countingStream, totalSizeForSending)
    lblFile = "Sending: " & currentFile
    timer1.Enabled = True
    SendingFile = True
    UpdateProgress
End Sub

i go test your samples with b4j

a_carignan · Jan 18, 2015

I programmed with Purebasic a server to receive files sent by my phone. I rencotre three problems.
1) The file name is not communicating with the server.
2) Two lines entours the file contents, these lines are visible in an HTML file, plus it makes a JPG file unreadable.
3) Sometimes my server software opens once more to send the file. All open files are identical.
Hopefully we will you give me pourez possible solutions.
Ps. Everything leads me to believe that the content of the file is sent in tags, but I do not know how to capture them.

Erel · Jan 18, 2015

I recommend you to use B4J to implement such a server. It will be much simpler as you can share almost all of the code.

https://www.b4x.com/android/forum/threads/37201/#content

a_carignan · Jan 20, 2015

Erel said:
I recommend you to use B4J to implement such a server. It will be much simpler as you can share almost all of the code.

https://www.b4x.com/android/forum/threads/37201/#content

I tried your solution but I can not implement it yet. Then, somehow, I must find the means to tell my PureBasic software file has arrived. Since the software that communicates the file that I want to transfer are already well advanced. I am the last additions to the software, not the beginning. Among the latest addition, I would like to send given by Bluetooth and WiFi. That is why I would like to know what is sent with the file, so I can rid myself. The file name is unimportant to me, since it will probably be the same every time.

Erel · Jan 20, 2015

Implementing AsyncStreams.WriteStream in a different language will be quite complicated. You can check the C# code I posted here:
https://www.b4x.com/android/forum/t...ement-asyncstreams-prefix-mode.30741/#content

a_carignan · Jan 23, 2015

Thank you for information, I finally managed to transfer files. Here's what I finally understood the contents of the given ennvoyé for those interested.
1 - The number of characters of the file name.
2 - The name of the file.
3-4 bytes that seems to serve no purpose.
4 - The size of the file.
5 - The actual file.
6 - Return of 4 byte end junk.

Erel · Jan 25, 2015

You didn't understand correctly I'm afraid.

The first 4 bytes encode the total length and the last 4 bytes are Adler 32 checksum.

a_carignan · Jan 26, 2015

The software you create sent the file name and file such time, my list is taking in count. The software that I designed to receive RECEIVE gave them several block and this creates SEVERAL receptions event. This is why I created a temporary file that receives the given and eventually I created the file destinations from its data. Laziness, I do not have to try to understand the checksum is why I called junk. While this information is undoubtedly important for the proper test data sent, but I have not needed.

Dale_Schroeder · Feb 18, 2015

can someone tell me how they got the buttons and edittext box's different colors in this app then the default light grey?

Android Tutorial FileTransfer - Send and receive files with AsyncStreams

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