java.io.IOException: Software caused connection abort while print data in Bluetooth printer

[Samir Dasgupta]

Hello,

I am trying to create a demo app in Android which will basically do the following:

Search for bluetooth device. The devices will be displayed in a ListView.

On clicking any device, it will attempt to make a connection to the Bluetooth device.

After connection to a device is successful, a TextBox will be displayed with a Print button.

On clicking the Print button, the contents of the texts will be sent to a Bluetooth printer for printing.

I am able to make connection with the Bluetooth printer successfully. However on press on the "Print" button I am getting the exception:

BluetoothSocket﹕ java.io.IOException: Software caused connection abort
        at android.bluetooth.BluetoothSocket.writeNative(Native Method)
        at android.bluetooth.BluetoothSocket.write(BluetoothSocket.java:399)
        at android.bluetooth.BluetoothOutputStream.write(BluetoothOutputStream.java:89)
        at java.io.OutputStream.write(OutputStream.java:82)
        at com.mycompany.samdasgu.bluetoothprintdemo.AndroidBluetoothUtils.printData(AndroidBluetoothUtils.java:209)

Following are the related code for Bluetooth connection and Printing.

AndroidBluetoothUtils.java(A utility class for all BT related activities)

private static final String TAG = AndroidBluetoothUtils.class.getSimpleName();
 
// needed for communication to bluetooth device / network
private static OutputStream mmOutputStream;
private static InputStream mmInputStream;
private static BluetoothSocket mmSocket;
private static BluetoothAdapter bluetoothAdapter;
private static byte[] readBuffer;
private static int readBufferPosition;
private static volatile boolean stopWorker;
private static Thread workerThread;
 
//private static final UUID SERIAL_PORT_COMM_UUID = UUID.fromString("00001101-0000-1000-8000-00805f9b34fb");
 
/**
 * Utility method to check current bluetooth status
 *
 * @return Bluetooth status of device,
 * NULL= bluetooth is not available,
 * TRUE = bluetooth is turned on currently,
 * FALSE = bluetooth is turned off now
 */
 
public static Boolean getBluetoothStatus() {
    if(bluetoothAdapter == null) {
        bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
    }
    Boolean status = null;
    if (bluetoothAdapter != null) {
        Log.d(TAG, "Default bluetooth adapter IS FOUND");
        // Blue-tooth is either turned off or on
        status = bluetoothAdapter.isEnabled();
    } else {
        Log.d(TAG, "Default bluetooth adapter not found");
    }
    return status;
}
 
 
/**
 * Utility method to turn blue-tooth on/off
 *
 * @param enableFlag
 */
public static void turnOnOffBluetooth(final boolean enableFlag) {
    if(bluetoothAdapter == null) {
        bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
    }
    final Boolean currentStatus = getBluetoothStatus();
    if (currentStatus != null) {
        if (enableFlag) {
            Log.d(TAG, "Turning ON bluetooth");
            bluetoothAdapter.enable();
            Log.d(TAG, "Bluetooth adapter is turned ON");
        } else {
            Log.d(TAG, "Turning OFF bluetooth");
            bluetoothAdapter.disable();
            Log.d(TAG, "Bluetooth adapter is turned OFF");
        }
    }
}
 
/**
 *
 */
 
public static void searchBluetoothDevices() {
    if(bluetoothAdapter == null) {
        bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
    }
    if (bluetoothAdapter != null) {
        Log.d(TAG, "Searching bluetooth discovery");
        if(!bluetoothAdapter.isDiscovering()) {
            bluetoothAdapter.startDiscovery();
        }
    }
}
 
/**
 * Tries to connect to a Bluetooth device
 * @param mDevice
 * @throws IOException
 */
public static void connectDevice(BluetoothDevice mDevice) throws IOException{
 
    if(bluetoothAdapter == null) {
        bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
    }
 
    Log.d(TAG, "Attempting to connect to device");
    if(bluetoothAdapter.isDiscovering()) {
        bluetoothAdapter.cancelDiscovery();
    }
 
    UUID uuid = mDevice.getUuids()[0].getUuid();
 
    mmSocket = mDevice.createRfcommSocketToServiceRecord(uuid);
    mmOutputStream = mmSocket.getOutputStream();
    mmInputStream = mmSocket.getInputStream();
    mmSocket.connect();
 
    //Listen data for Print Activity
    listenForData();
 
    Log.d(TAG,"Bluetooth device is connected");
}
 
// close the connection to bluetooth device.
public static void disconnect() throws IOException {
    try {
        stopWorker = true;
        mmOutputStream.close();
        mmInputStream.close();
        mmSocket.close();
        Log.d(TAG, "Bluetooth device is disconnected");
    } catch (Exception e) {
        Log.e(TAG, "Error in closing Bluetooth connection", e);
    }
}
 
 
/*
 * after opening a connection to bluetooth printer device,
 * we have to listen and check if a data were sent to be printed.
 */
public static void listenForData() {
 
    try {
        // this is the ASCII code for a newline character
        final byte delimiter = 10;
 
        stopWorker = false;
        readBufferPosition = 0;
        readBuffer = new byte[1024];
 
        workerThread = new Thread(new Runnable() {
            public void run() {
 
        while (!Thread.currentThread().isInterrupted() && !stopWorker) {
 
            try {
 
                int bytesAvailable = mmInputStream.available();
 
                if (bytesAvailable > 0) {
 
                    byte[] packetBytes = new byte[bytesAvailable];
                    mmInputStream.read(packetBytes);
 
                    for (int i = 0; i < bytesAvailable; i++) {
 
                        byte b = packetBytes[i];
                        if (b == delimiter) {
 
                            byte[] encodedBytes = new byte[readBufferPosition];
                            System.arraycopy(
                                    readBuffer, 0,
                                    encodedBytes, 0,
                                    encodedBytes.length
                            );
 
                            readBufferPosition = 0;
                        } else {
                            readBuffer[readBufferPosition++] = b;
                        }
                    }
                }
 
            } catch (IOException ex) {
                stopWorker = true;
            }
 
        }
            }
        });
 
        workerThread.start();
        Log.d(TAG, "Listening for incoming print data in work thread");
    } catch (Exception e) {
        Log.e(TAG, "Error in starting print worker thread", e);
    }
}
 
// this will send text data to be printed by the bluetooth printer
public static void printData(byte[] bytes) throws IOException {
    try {
        // the text typed by the user
        mmOutputStream.write(bytes);
        mmOutputStream.flush();
        try {
            Thread.sleep(20);
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    } catch (Exception e) {
        Log.e(TAG, "Issue in printing data", e);
    }
}

BluetoothAdapter.java(A custom BaseAdapter created for a ListView which will display the Bluetooth device on search and on click of list item will attempt to connect to the device)

private transient List<BluetoothDevice> deviceList = null;
    private transient Context mContext = null;
    private final static String TAG = BluetoothArrayAdapter.class.getSimpleName();
 
    public BluetoothArrayAdapter(final List<BluetoothDevice> deviceList, final Context mContext) {
        super();
        this.deviceList = deviceList;
        this.mContext = mContext;
    }
 
    public void setDeviceList(final List<BluetoothDevice> deviceList){
        this.deviceList = deviceList;
    }
 
 
 
    //To recycle the list view
    private class ViewHolder {
        TextView btDeviceNameTv;
        TextView btDeviceAddrTv;
        View tvContainer;
    }
 
    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        /***Implementing ViewHolder Pattern ****/
        Log.d(TAG, "Drawing view position id =" + position);
        View vw = convertView;
        ViewHolder holder;
        //BluetoothDevice device = deviceList.get(position);
        if (vw == null) {
            final LayoutInflater inflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            vw = inflater.inflate(R.layout.bluetooth_search_layout_row, null);
            holder = new ViewHolder();
            // Lookup the view elements
            holder.btDeviceNameTv = (TextView)vw.findViewById(R.id.btDeviceNameTv);
            holder.btDeviceAddrTv = (TextView)vw.findViewById(R.id.btDeviceAddrTv);
            holder.tvContainer = vw.findViewById(R.id.tvContainer);
            vw.setOnClickListener(this);
            vw.setOnTouchListener(this);
            vw.setTag(holder);
        } else {
            holder = (ViewHolder) vw.getTag();
        }
 
        final BluetoothDevice device = (BluetoothDevice) getItem(position);
        if(device != null) {
            // Populate device name
            if (device.getName() != null && !device.getName().equals("")
                    && holder.btDeviceNameTv != null) {
                holder.btDeviceNameTv.setText(device.getName());
            }
            // Populate device address
            if (device.getAddress() != null && !device.getAddress().equals("")
                    && holder.btDeviceAddrTv != null) {
                holder.btDeviceAddrTv.setText(device.getAddress());
            }
 
            if(holder.tvContainer!=null){
                // Touch will be handled by the adapter
                holder.tvContainer.setTag(device);
            }
        }
        /****End***/
        return vw;
    }
 
    @Override
    public int getCount(){
        int size = 0;
        if(this.deviceList!=null){
            size = this.deviceList.size();
        }
        return size;
    }
 
    @Override
    public Object getItem(int position) {
        Object obj = null;
 
        if(this.deviceList!=null && this.deviceList.size()>position){
            obj = this.deviceList.get(position);
            Log.d(TAG,"Object retrieved for position="+position);
        }
        return obj;
    }
 
    @Override
    public long getItemId(int position) {
        return 0;
    }
 
    @Override
    public boolean onTouch(View v, MotionEvent event) {
        if(event.getAction()== MotionEvent.ACTION_DOWN){
            if(v.getId()==R.id.btSearchIndivRowLayout){
                v.setBackgroundColor(mContext.getResources().getColor(android.R.color.holo_blue_light));
            }
        } else if(event.getAction()==MotionEvent.ACTION_UP){
            v.performClick();
        }
        return true;
    }
 
    @Override
    public void onClick(View view) {
        if(view != null  && view.getId() == R.id.btSearchIndivRowLayout) {
            if(view.getTag() != null && view.getTag() instanceof ViewHolder) {
                ViewHolder viewHolder = (ViewHolder) view.getTag();
                if(viewHolder.tvContainer.getTag() != null && viewHolder.tvContainer.getTag() instanceof BluetoothDevice) {
                    final BluetoothDevice device = (BluetoothDevice) viewHolder.tvContainer.getTag();
                    AlertDialog.Builder dialog = new AlertDialog.Builder(mContext);
                    dialog.setTitle("Connect to bluetooth device");
                    dialog.setMessage("Do you want to connect ?");
                    dialog.setIcon(android.R.drawable.ic_dialog_alert);
                    dialog.setCancelable(false);
                    dialog.setPositiveButton("Connect",
                            new DialogInterface.OnClickListener() {
                                @Override
                                public void onClick(DialogInterface dialog, int which) {
                                    dialog.dismiss();
 
                                    try {
                                        AndroidBluetoothUtils.connectDevice(device);
                                        Intent intent = new Intent(mContext, PrintActivity.class);
                                        mContext.startActivity(intent);
                                    } catch (IOException e) {
                                        Log.e(TAG, "Error in connecting to Bluetooth device", e);
                                    }
                                }
                            }
 
                    );
                                dialog.setNegativeButton("Cancel", null);
                                dialog.create();
                                dialog.show();
                            }
                }
        }
    }

I am calling the AndroidBluetoothUtils.printData(printNoteMessage.getBytes()) from another Activity on the onClick event of the "Print" button.

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
 
import java.io.IOException;
 
 
public class PrintActivity extends Activity {
 
    private static final String TAG = PrintActivity.class.getSimpleName();
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_print);
        final EditText printNote = (EditText) findViewById(R.id.printNote);
        final Button buttonDisconnect = (Button) findViewById(R.id.buttonDisconnect);
 
 
        buttonDisconnect.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                try {
                    AndroidBluetoothUtils.disconnect();
                    Intent intent = new Intent(getApplicationContext(), MainActivity.class);
                    startActivity(intent);
                } catch (IOException e) {
                    Log.e(TAG, "Error in closing Bluetooth connection", e);
                }
            }
        });
 
 
        final Button buttonPrint = (Button) findViewById(R.id.buttonPrint);
        buttonPrint.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String printNoteMessage = printNote.getText().toString();
                try {
                    AndroidBluetoothUtils.printData(printNoteMessage.getBytes());
                    Toast.makeText(getApplicationContext(),"Data sent for printing",Toast.LENGTH_SHORT).show();
                } catch (IOException e) {
                    Log.e(TAG, "Error in printing data", e);
                }
            }
        });
    }
}

Is there something I am doing wrong in this approach ? I have been trying to google this problem without finding the cause for this exception. Please help as I have been stuck with this issue for over a week now.