Question

I am facing a problem in sending large files over bluetooth sockets. Smaller files get transferred correctly. I believe upto 161280 bytes get transferred correctly.

EDIT: I did some more testing and narrowed down the cause. It seems that

outStream.write(mybytearray, 0, mybytearray.length);

in the sending code part is NOT writing more than 161280 bytes. I saw this behavior by not closing the socket connection, thereby causing the read in the receiving part to “block” on 161280 bytes. What is wrong with the bluetooth output stream here? What am I doing wrong?

EDIT 2:
Doing this lets it through.

for(int i = 0 ; i < mybytearray.length ; i++){
    outStream.write(mybytearray[i]);
}

Sending code:

    try {
        outStream = mBluetoothSocket.getOutputStream();
        Log.d(TAG,"outStream created success!");
    } catch (IOException e) {
        Log.d(TAG,
                "ON RESUME: Output stream creation failed.",
                e);
    }

    File myFile = new File(file_name);
    Log.d(TAG,"file /source.pdf created success!");

    byte[] mybytearray = new byte[(int)myFile.length()];
    Log.d(TAG,"file length() =" + (int)myFile.length());

    FileInputStream fis = new FileInputStream(myFile);
    Log.d(TAG,"fis created");

    BufferedInputStream bis = new BufferedInputStream(fis,1272254 );
    Log.d(TAG,"bis created success");

    bis.read(mybytearray,0,mybytearray.length);
    Log.d(TAG,"ALL Bytes read from bis");

    outStream.write(mybytearray, 0, mybytearray.length);
    Log.d(TAG,"BYTES WRITTEN to OUTSTREAM of socket");


    outStream.flush();
    Log.d(TAG,"bytes flushed");
    outStream.close();

Receiving code:

// Attach the i/p stream to the socket
    try {
        InputStream in = socket.getInputStream();
        mIn = in;
        Log.d(TAG, "input stream acquired");

    } catch (IOException e1) {
        e1.printStackTrace();
    }
    // Create output streams & write to file
    FileOutputStream fos = new FileOutputStream(
            Environment.getExternalStorageDirectory()
                    + "/copy.pdf");
    try {
        bytesRead = mIn.read(buffer, 0, buffer.length);
        Log.d(TAG, "bytesRead first time =" + bytesRead);
        current = bytesRead;

        do {
            Log.d(TAG, "do-while -- current: " + current);
            bytesRead = mIn.read(buffer, current,
                    buffer.length - current);
            Log.d(TAG, "bytesRead: =" + bytesRead);

            if (bytesRead >= 0)
                current += bytesRead;
        } while (bytesRead > -1);
    } catch (IOException e) {
        e.printStackTrace();
        Log.d(TAG, "do while end:-- buffer len= "
                + buffer.length + "  current: " + current);

        fos.write(buffer);
        Log.d(TAG, "fos.write success! buffer: "
                + buffer.length + "  current: " + current);

        fos.flush();
        fos.close();
    }
}
socket.close();

Logcat:

D/ReceiveService( 5761): do-while -- current: 155232
D/ReceiveService( 5761): bytesRead: =1008
D/ReceiveService( 5761): do-while -- current: 156240
D/ReceiveService( 5761): bytesRead: =1008
D/ReceiveService( 5761): do-while -- current: 157248
D/ReceiveService( 5761): bytesRead: =1008
D/ReceiveService( 5761): do-while -- current: 158256
D/ReceiveService( 5761): bytesRead: =1008
D/ReceiveService( 5761): do-while -- current: 159264
D/ReceiveService( 5761): bytesRead: =1008
D/ReceiveService( 5761): do-while -- current: 160272
D/ReceiveService( 5761): bytesRead: =1008
D/ReceiveService( 5761): do-while -- current: 161280
W/System.err( 5761): java.io.IOException: Software caused connection abort
W/System.err( 5761):    at android.bluetooth.BluetoothSocket.readNative(Native Method)
W/System.err( 5761):    at android.bluetooth.BluetoothSocket.read(BluetoothSocket.java:307)
W/System.err( 5761):    at   android.bluetooth.BluetoothInputStream.read(BluetoothInputStream.java:96)
W/System.err( 5761):    at com.bt.server.ReceiveService$AcceptThread.run(ReceiveService.java:141)

I am using Motorola Milestone. Android 2.1

Answer 1

I was able to solve this problem by sending small chunks of data out to the bluetooth outstream. It turned out that 8 * 1024 was a good buffer size, which helped in sending out data seamlessly over the stream as well as preventing corruption of data at the receiving end.

BufferedInputStream bis = new BufferedInputStream(fis, 8 * 1024);


byte[] buffer = new byte[8192];
int len
while ((len = bis.read(buffer)) != -1) {
    outStream.write(buffer, 0, len);
}