bluetooth pair and connect device

Question

I want to pair the device and connect it ,but I have a problem ,I just can pair device but I am not able to connect them. I want to know how to solve this problem. I'm afraid, I have not explained my problem very well, I can not connect means, connect your phone to a Bluetooth headset and I can only pair, here is the code

 if (btAdapt.isEnabled()) {
                    tbtnSwitch.setChecked(false);
            } else {
                    tbtnSwitch.setChecked(true);
            }
            // ============================================================

            IntentFilter intent = new IntentFilter();
            intent.addAction(BluetoothDevice.ACTION_FOUND);
            intent.addAction(BluetoothDevice.ACTION_BOND_STATE_CHANGED);
            intent.addAction(BluetoothAdapter.ACTION_SCAN_MODE_CHANGED);
            intent.addAction(BluetoothAdapter.ACTION_STATE_CHANGED);
            registerReceiver(searchDevices, intent);
    }

    private BroadcastReceiver searchDevices = new BroadcastReceiver() {

            public void onReceive(Context context, Intent intent) {
                    String action = intent.getAction();
                    Bundle b = intent.getExtras();
                    Object[] lstName = b.keySet().toArray();


                    for (int i = 0; i < lstName.length; i++) {
                            String keyName = lstName[i].toString();
                            Log.e(keyName, String.valueOf(b.get(keyName)));
                    }
                    BluetoothDevice device = null;

                    if (BluetoothDevice.ACTION_FOUND.equals(action)) {
                            device = intent
                                            .getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
                            if (device.getBondState() == BluetoothDevice.BOND_NONE) {
                                    String str = "no pair|" + device.getName() + "|"
                                                    + device.getAddress();
                                    if (lstDevices.indexOf(str) == -1)
                                            lstDevices.add(str); 
                                    adtDevices.notifyDataSetChanged();
                            }
                    }else if(BluetoothDevice.ACTION_BOND_STATE_CHANGED.equals(action)){
                            device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
                            switch (device.getBondState()) {
                            case BluetoothDevice.BOND_BONDING:
                                    Log.d("BlueToothTestActivity", "it is pairing");
                                    break;
                            case BluetoothDevice.BOND_BONDED:
                                    Log.d("BlueToothTestActivity", "finish");
                                    connect(device);
                                    break;
                            case BluetoothDevice.BOND_NONE:
                                    Log.d("BlueToothTestActivity", "cancel");
                            default:
                                    break;
                            }
                    }

            }
    };

    @Override
    protected void onDestroy() {
            this.unregisterReceiver(searchDevices);
            super.onDestroy();
            android.os.Process.killProcess(android.os.Process.myPid());
    }

    class ItemClickEvent implements AdapterView.OnItemClickListener {

            public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) 
            {
                    if(btAdapt.isDiscovering())btAdapt.cancelDiscovery();
                    String str = lstDevices.get(arg2);
                    String[] values = str.split("\\|");
                    String address = values[2];
                    Log.e("address", values[2]);
                    BluetoothDevice btDev = btAdapt.getRemoteDevice(address);
                    try {
                            Boolean returnValue = false;
                            if (btDev.getBondState() == BluetoothDevice.BOND_NONE) {
                                  BluetoothDevice.createBond(BluetoothDevice remoteDevice);
                                    Method createBondMethod = BluetoothDevice.class
                                                    .getMethod("createBond");
                                    Log.d("BlueToothTestActivity", "start");
                                    returnValue = (Boolean) createBondMethod.invoke(btDev);

                            }else if(btDev.getBondState() == BluetoothDevice.BOND_BONDED){
                                    connect(btDev);
                            }
                    } catch (Exception e) {
                            e.printStackTrace();
                    }

            }

    }

    private void connect(BluetoothDevice btDev) {
            UUID uuid = UUID.fromString(SPP_UUID);
            try {
                    btSocket = btDev.createInsecureRfcommSocketToServiceRecord(uuid);
                    Log.d("BlueToothTestActivity", "connecting...");
                    btSocket.connect();
            } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
            }
    }

    class ClickEvent implements View.OnClickListener {
            public void onClick(View v) {
                    if (v == btnSearch)
                    {
                            if (btAdapt.getState() == BluetoothAdapter.STATE_OFF) {
                                    Toast.makeText(BlueToothTestActivity.this, "please open", 1000)
                                                    .show();
                                    return;
                            }
                            if (btAdapt.isDiscovering())
                                    btAdapt.cancelDiscovery();
                            lstDevices.clear();
                            Object[] lstDevice = btAdapt.getBondedDevices().toArray();
                            for (int i = 0; i < lstDevice.length; i++) {
                                    BluetoothDevice device = (BluetoothDevice) lstDevice[i];
                                    String str = "pair|" + device.getName() + "|"
                                                    + device.getAddress();
                                    lstDevices.add(str); 
                                    adtDevices.notifyDataSetChanged();
                            }
                            setTitle("address：" + btAdapt.getAddress());
                            btAdapt.startDiscovery();
                    } else if (v == tbtnSwitch) {
                            if (tbtnSwitch.isChecked() == false)
                                    btAdapt.enable();

                            else if (tbtnSwitch.isChecked() == true)
                                    btAdapt.disable();
                    } else if (v == btnDis)
                    {
                            Intent discoverableIntent = new Intent(
                                            BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);
                            discoverableIntent.putExtra(
                                            BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION, 300);
                            startActivity(discoverableIntent);
                    } else if (v == btnExit) {
                            try {
                                    if (btSocket != null)
                                            btSocket.close();
                            } catch (IOException e) {
                                    e.printStackTrace();
                            }
                            BlueToothTestActivity.this.finish();
                    }
            }

    }

}

Answer 1

You have not specified, but I assume your problem is in the socket creation part rather than the actual connect() call. This is where things usually go wrong.

How to fix?

1. Your code assumes the headset supports insecure BT communications. In many cases this is true, but not in all. Try calling createRfcommSocketToServiceRecord() instead

2. Your code uses the default SPP UUID for the RFCOMM channel lookup. For API versions >= 15 this is the wrong thing to do. Instead try calling device.getUuids() and use the first returned UUID as the creation parameter. From my own experience, even for pre-15 API versions you can still call getUuids() and get good results, but you will need to do it by reflection. Only if the above fails should you attempt socket creation with the default SPP UUID

3. If the above fails, you may try, as a last resort, to activate the "createRfcommSocket" hidden API . That had worked for me several occasions, and on multiple Android versions. Use java reflection to activate this call and, since inherently not safe, protect it with try catch.

4. Remember to place your logic in an AsyncTask or something. You do not want the UI thread to block on such tasks!

Finally feel free to use https://github.com/giladHaimov/BTWiz for a much simpler handling of the Bluetooth connect and for simple async IO interface.