Android Bluetooth Low Energy (BLE) - cooking correctly, part # 2 (connecting / disconnecting)

Content

Part # 1 (scanning).

Part # 2 (connecting / disconnecting), you are here.

In the  previous article,  we looked at device scanning in detail. This article is about  connecting ,  disconnecting,  and  discovering services  .

Connect to device

, ,  connectGatt()



. – BluetoothGatt



,  GATT , . ,  connectGatt()



. Android , Android-6 :

BluetoothGatt connectGatt(Context context, boolean autoConnect,
        BluetoothGattCallback callback)
BluetoothGatt connectGatt(Context context, boolean autoConnect,
        BluetoothGattCallback callback, int transport)
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

–  transport = TRANSPORT_AUTO



. BLE . TRANSPORT_AUTO



  BLE Bluetooth . , Android . , .  connectGatt()



  transport = TRANSPORT_LE



:

BluetoothGatt gatt = device.connectGatt(context, false, 
    bluetoothGattCallback, TRANSPORT_LE);
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

– context



 . –  autoconnect



, (false



) (true



). (false



) Android 30 ( ),  status_code = 133



. . Android  GATT_ERROR



. , . ,  autoconnect = false



Android ( - , ). –  BluetoothGattCallback



 (callback) . , . .

Autoconnect = true

 autoconnect = true



, Android , . : Bluetooth – . , , . , .  BluetoothDevice



   connectGatt



  autoconnect = true



.

BluetoothDevice device = 
bluetoothAdapter.getRemoteDevice("12:34:56:AA:BB:CC");

BluetoothGatt gatt = 
device.connectGatt(context, true, bluetoothGattCallback, TRANSPORT_LE);
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, , Bluetooth (bonding).   , Bluetooth . / Bluetooth ( Airplane ) – ,  autoconnect = true



, .

Autoconnect (bonded) !

, , , .  BluetoothDevice



,  getType



, – TYPE_UNKNOWN



, . , - ( ) .

Android-6 , (autoconnect = false



). , Polidea   . , .

:

• Android (. - Android-8 ).

  
  
  
  
  

• ;

  
  
  
  
  

:

• , +  autoconnect = false
  
  
  
  . Android  SCAN_MODE_LOW_POWER
  
  
  
  , .

  
  
  
  
  

 connectGatt()



, Bluetooth  onConnectionStateChange



, .

– . ( ):

public void onConnectionStateChange(final BluetoothGatt gatt, 
                                    final int status, 
                                    final int newState) {
    if (newState == BluetoothProfile.STATE_CONNECTED) {
        gatt.discoverServices();
    } else {
        gatt.close();
    }
}
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

 newState



   status



. . , , –  discoverServices()



. -  close()



, Android Bluetooth. BLE Android, !

 connectGatt()



, Bluetooth (client interface: clientIf



).

LogCat:

D/BluetoothGatt: connect() - device: B0:49:5F:01:20:XX, auto: false
D/BluetoothGatt: registerApp()
D/BluetoothGatt: registerApp() — UUID=0e47c0cf-ef13–4afb-9f54–8cf3e9e808d5
D/BluetoothGatt: onClientRegistered() — status=0 clientIf=6
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

,  6



   connectGatt()



. () Android 30 ( GATT_MAX_APPS



  ), – Android . , Android 5 6 , , Android . ,  close()



,  connectGatt()



.  close()



, Bluetooth , .

D/BluetoothGatt: close()
D/BluetoothGatt: unregisterApp() — mClientIf=6
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

 close()



  ! .

(newState)

 newState



  4 :

• STATE_CONNECTED
  
  
  
  

  
  
  
  
  

• STATE_DISCONNECTED
  
  
  
  

  
  
  
  
  

• STATE_CONNECTING
  
  
  
  

  
  
  
  
  

• STATE_DISCONNECTING
  
  
  
  

  
  
  
  
  

.  STATE_CONNECTING



, STATE_DISCONNECTING



  , . , , , , (. - , ),  close()



  .

(status)

,  status



  , . , , .  GATT_SUCCESS



  , . , - .  GATT_SUCCESS



, «- »  status



  . ,  BluetoothGatt



  ,  . 133 (GATT_ERROR



). , – « - ». ,  GATT_ERROR



 .

,  newState



  status



,  onConnectionStateChange



:

public void onConnectionStateChange(final BluetoothGatt gatt, 
                                    final int status, 
                                    final int newState) {
if(status == GATT_SUCCESS) {
    if (newState == BluetoothProfile.STATE_CONNECTED) {
        //  ,    
        gatt.discoverServices();
    } else if (newState == BluetoothProfile.STATE_DISCONNECTED) {
        //    ( )
        gatt.close();
    } else {
        //     ,    
    }
} else {
   //  ... ,  !
   ...
   gatt.close();
} 
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, . , .

bonding (bondState)

,  onConnectionStateChange



 –  bondState



, (bonding) . :

int bondstate = device.getBondState();
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

bonding  BOND_NONE



, BOND_BONDING



 or BOND_BONDED



. , .

• BOND_NONE
  
  
  
  , ,  discoverServices()
  
  
  
  ;

  
  
  
  
  

• BOND_BONDING
  
  
  
  , ,  discoverServices()
  
  
  
  , Bluetooth  discoverServices()
  
  
  
  . discoverServices()
  
  
  
  , (bonding);

  
  
  
  
  

• BOND_BONDED
  
  
  
  , Android-8 ,  discoverServices()
  
  
  
    . 7 .  Service Changed Characteristic, Bluetooth  discoverServices()
  
  
  
    . 1000-1500 , . ,  Service Changed Characteristic  .

  
  
  
  
  

 bondState



   status



  newState



:

if (status == GATT_SUCCESS) {
    if (newState == BluetoothProfile.STATE_CONNECTED) {
        int bondstate = device.getBondState();
        //  bondState
        if(bondstate == BOND_NONE || bondstate == BOND_BONDED) {
            //   ,  discoverServices  
            int delayWhenBonded = 0;
            if (Build.VERSION.SDK_INT <= Build.VERSION_CODES.N) {
                delayWhenBonded = 1000;
            }
            final int delay = bondstate == BOND_BONDED ? delayWhenBonded : 0;
            discoverServicesRunnable = new Runnable() {
                @Override
                public void run() {
                    Log.d(TAG, String.format(Locale.ENGLISH, "discovering services of '%s' with delay of %d ms", getName(), delay));
                    boolean result = gatt.discoverServices();
                    if (!result) {
                        Log.e(TAG, "discoverServices failed to start");
                    }
                    discoverServicesRunnable = null;
                }
            };
            bleHandler.postDelayed(discoverServicesRunnable, delay);
        } else if (bondstate == BOND_BONDING) {
            // Bonding  ,   
            Log.i(TAG, "waiting for bonding to complete");
        }
....
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, . , «», .

• . , . - 19 (GATT_CONN_TERMINATE_PEER_USER
  
  
  
  );

  
  
  
  
  

• . - 8 (GATT_CONN_TIMEOUT
  
  
  
  );

  
  
  
  
  

• , . - 133 (GATT_ERROR
  
  
  
  ) , ;

  
  
  
  
  

• Bluetooth . - 133 (GATT_ERROR
  
  
  
  );

  
  
  
  
  

•  bonding



  discoverServices
  
  
  
  . .

  
  
  
  
  

-  close()



   BluetoothGatt



, . , , , - . UI , - .   .

133 (connecting)

- 133 , . , :

• ,  close()
  
  
  
    . ,  status=133
  
  
  
  ;

  
  
  
  
  

•  TRANSPORT_LE



   connectGatt()
  
  
  
  ;

  
  
  
  
  

• . Bluetooth . (. : / Bluetooth, Airplane - );

  
  
  
  
  

• advertising .  connectGatt()



  autoconnect = false
  
  
  
    30 ,  status=133
  
  
  
  ;

  
  
  
  
  

• / . ;

  
  
  
  
  

133,   ! Android , . 133 ,  close()



  , ! , Android  close()



  . - , – !

(disconnect)

:

•  disconnect()
  
  
  
  ;

  
  
  
  
  

•  onConnectionStateChange
  
  
  
  ;

  
  
  
  
  

•  close()
  
  
  
  ;

  
  
  
  
  

• gatt ;

  
  
  
  
  

 disconnect()



  Bluetooth .  onConnectionStateChange



  «disconnected».

 close()



    BluetoothGattCallback



  Bluetooth .

,  BluetoothGatt



  .

«»

, , :

•  disconnect()
  
  
  
  

  
  
  
  
  

•   close()
  
  
  
  

  
  
  
  
  

-. , «disconnected». ,  disconnect()



  ( ),  close()



  ! , Android , .

 disconnect()



,  close()



. , ,  disconnect()



  (  autoconnect = true



). ,  close()



, .

 connectGatt()



,  disconnect()



. ,  onConnectionStateChange



  !  disconnect()



   close()



 (. : 50-100).

:

D/BluetoothGatt: cancelOpen() — device: CF:A9:BA:D9:62:9E
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, ,  autoconnect = false



.  autoconnect = true



. , – , .

. :  autoconnect = false



  !

(discovering services)

,  discoverServices()



. Bluetooth  ,   . , , .  onServicesDiscovered.

, :

//    ?   - 
if (status == GATT_INTERNAL_ERROR) {
    Log.e(TAG, "Service discovery failed");
    disconnect();
    return;
}
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

(  GATT_INTERNAL_ERROR



  129), , - ( ). .

, :

final List<BluetoothGattService> services = gatt.getServices();
Log.i(TAG, String.format(Locale.ENGLISH,"discovered %d services for '%s'", services.size(), getName()));
//     ( )
...
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

.

Bluetooth , . , – . Bluetooth. . , , . : , , , . Java:

private boolean clearServicesCache() {
    boolean result = false;
    try {
        Method refreshMethod = bluetoothGatt.getClass().getMethod("refresh");
        if(refreshMethod != null) {
            result = (boolean) refreshMethod.invoke(bluetoothGatt);
        }
    } catch (Exception e) {
        Log.e(TAG, "ERROR: Could not invoke refresh method");
    }
    return result;
}
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, !

/

, , .

• 133 , ;

  
  
  
  
  

• ,  onConnectionStateChange
  
  
  
  . , Bluetooth. , . – – ;

  
  
  
  
  

• . , Huawei P8 Lite . (. : !);

  
  
  
  
  

• / . , , . (. : 50-100 ).

  
  
  
  
  

: .

/ , – , .

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