Clever Geek Handbook

Android Bluetooth Low Energy (BLE) - richtig kochen, Teil 4 (Bonding)

Inhalt





Teil 1 (Scannen)





Teil 2 (Verbinden / Trennen)





Teil 3 (Lesen / Schreiben)





Teil 4 (Kleben), Sie sind hier





Im  vorherigen Artikel haben  wir die Lese- / Schreibvorgänge, Aktivierungs- / Deaktivierungsbenachrichtigungen und Warteschlangenbefehle herausgefunden. In diesem Artikel werden wir über das Pairing von Geräten sprechen   ( Hinweis des Übersetzers - weiter werde ich den Begriff "Bonding" verwenden ).





Verbindung

Einige Geräte benötigen eine Verbindung, um ordnungsgemäß zu funktionieren. Technisch bedeutet dies, dass Verschlüsselungsschlüssel für einen sicheren Datenaustausch generiert, ausgetauscht und gespeichert werden. Beim Starten des Verbindungsvorgangs kann Android den Benutzer um Zustimmung, PIN-Code oder Passphrase bitten. Bei den nächsten Verbindungen weiß Android bereits, dass das Gerät gekoppelt ist und Verschlüsselungsschlüssel ohne Benutzereingriff heimlich ausgetauscht werden. Durch die Verwendung von Bonding wird die Verbindung zum Gerät sicherer, da die Verbindung verschlüsselt ist.





bonding Google, , bonding.  createBond()



. , iOS  CoreBluetooth



  !  createBond()



? , , bonding, . Bluetooth , – bonding. . , , , .





bonding:





  • Android bonding. Android bonding , , bonding, / .  createBond()



      (. : , - . , Samsung -, );





  • , bonding.  / , . Android bonding;





  • bonding.  bonding , ;





  • , ,    createBond()



      bonding . .





bonding?

, bonding:





  1. , , bonding, ;





  2. «» .  , bonding. / , bonding – /  INSUFFICIENT_AUTHENTICATION



    . iOS.





  3.   bonding    createBond()



    . , iOS, . Bluetooth .





.





Bonding

bonding ,  onConnectionStateChange



  bonding  BOND_BONDING



. bonding   ,  discoverServices()



, bonding ! .  onConnectionStateChanged



:





// Take action depending on the bond state
if(bondstate == BOND_NONE || bondstate == BOND_BONDED) {
    // Connected to device, now proceed to discover it's services
    ... 
} else if (bondstate == BOND_BONDING) {
    // Bonding process has already started let it complete
    Log.i(TAG, "waiting for bonding to complete");
}

, bonding,  BroadcastReceiver



   ACTION_BOND_STATE_CHANGED



   connectGatt



. bonding.





context.registerReceiver(bondStateReceiver, 
                        new IntentFilter(ACTION_BOND_STATE_CHANGED));
private final BroadcastReceiver bondStateReceiver = new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {
        final String action = intent.getAction();
        final BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);

        // Ignore updates for other devices
        if (bluetoothGatt == null || !device.getAddress().equals(bluetoothGatt.getDevice().getAddress()))
            return;

        // Check if action is valid
        if(action == null) return;

        // Take action depending on new bond state
        if (action.equals(ACTION_BOND_STATE_CHANGED)) {
            final int bondState = intent.getIntExtra(EXTRA_BOND_STATE, ERROR);
            final int previousBondState = intent.getIntExtra(BluetoothDevice.EXTRA_PREVIOUS_BOND_STATE, -1);

            switch (bondState) {
                case BOND_BONDING:
                    // Bonding started
                    ...
                    break;
                case BOND_BONDED:
                    // Bonding succeeded
                    ...
                    break;
                case BOND_NONE:
                    // Oh oh
                    ...
                    break;
            }
        }
    }
};

bonding, (service discovery), , :





case BOND_BONDED:
    // Bonding succeeded
    Log.d(TAG, "bonded");

    // Check if there are services
    if(bluetoothGatt.getServices().isEmpty()) {
        // No services discovered yet
        bleHandler.post(new Runnable() {
            @Override
            public void run() {
                Log.d(TAG, String.format("discovering services of '%s'", getName()));
                boolean result = bluetoothGatt.discoverServices();
                if (!result) {
                    Log.e(TAG, "discoverServices failed to start");
                }
            }
        });
    }

, bonding .





Bonding /

bonding / , /  GATT_INSUFFICIENT_AUTHENTICATION



. Android-6, 7  onCharacteristicRead



/onCharacteristicWrite



, bonding Android. Android-8 Android bonding. Android-6, 7 / . , bonding.





, :





public void onCharacteristicRead(BluetoothGatt gatt, final BluetoothGattCharacteristic characteristic, int status) {
    // Perform some checks on the status field
    if (status != GATT_SUCCESS) {
        if (status == GATT_INSUFFICIENT_AUTHENTICATION ) {
            // Characteristic encrypted and needs bonding,
            // So retry operation after bonding completes
            // This only happens on Android 5/6/7
            Log.w(TAG, "read needs bonding, bonding in progress");
            return;
        } else {
            Log.e(TAG, String.format(Locale.ENGLISH,"ERROR: Read failed for characteristic: %s, status %d", characteristic.getUuid(), status));
            completedCommand();
            return;
        }
    }
...

bonding , :





case BOND_BONDED:
    // Bonding succeeded
    Log.d(TAG, "bonded");

    // Check if there are services
    ...
    // If bonding was triggered by a read/write, we must retry it
    if (Build.VERSION.SDK_INT < Build.VERSION_CODES.O) {
        if (commandQueueBusy && !manuallyBonding) {
            bleHandler.postDelayed(new Runnable() {
                @Override
                public void run() {
                    Log.d(TAG, "retrying command after bonding");
                    retryCommand();
                }
            }, 50);
        }
    }

bonding

,  createBond



 , , . , ? iOS  createBond()



, – bonding , iOS. iOS. BLE ,  createBond()



  - .





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  – .  BluetoothDevice



  MAC-, (bonding). … ! (. : , , , ).





bonding

Android, Bluetooth . , bonding .





.





, bonding . ,  removeBond()



, Java:





try {
    Method method = device.getClass().getMethod("removeBond", (Class[]) null);
    result = (boolean) method.invoke(device, (Object[]) null);
    if (result) {
        Log.i(TAG, "Successfully removed bond");
    }
    return result;
} catch (Exception e) {
    Log.e(TAG, "ERROR: could not remove bond");
    e.printStackTrace();
    return false;
}

bonding

BLE bonding . , bonding :





  • bonding





  • B bonding





  • , bonding .





bonding BOND_NONE



   BroadcastReceiver



. bonding, :





case BOND_NONE:
    if(previousBondState == BOND_BONDING) {
       // Bonding failed
       ...
    } else {
       // Bond lost
       ...
    }
    disconnect();
    break;

bonding, , . , Android bonding. .





, . bonding,     , Bluetooth . bonding, Android , , . .





Pairing

. : «pairing», «» - .





Android bonding, . «», (. : Samsung-S9, Android-10, , , , ). Google ( , Android ), .





Pairing :





  • ;





  • ;





  • « »;





  • Bluetooth .





«»   60 . ,   . , , . , . UI -! () ! Samsung - ( JustWorks) , . PIN- . . !





, , , . , . :





public void startPairingPopupHack() {
    String manufacturer = Build.MANUFACTURER;
    if(!manufacturer.equals("samsung")) {
        bluetoothAdapter.startDiscovery();

        callBackHandler.postDelayed(new Runnable() {
            @Override
            public void run() {
                Log.d(TAG, "popup hack completed");
                bluetoothAdapter.cancelDiscovery();
            }
        }, 1000);
    }
}

– BLE . .





, bonding !





…

BLE Android (. : -, BLE Android, ). BLE . BLE, . !





Sie können es kaum erwarten, mit BLE zu arbeiten? Probieren Sie  meine Blessed for Android-Bibliothek aus . Es verwendet alle Ansätze in dieser Artikelserie und erleichtert die Arbeit mit BLE in Ihrer Anwendung.











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