characteristic.getDescriptor()返回null

Question

我正在连接计步器到android.当我在setCharacteristicNotification函数中执行以下行时,我将描述符设为Null

BluetoothGattDescriptor descriptor = characteristic.getDescriptor(UUID.fromString(SampleGattAttributes.CLIENT_CHARACTERISTIC_CONFIG));



public static String CLIENT_CHARACTERISTIC_CONFIG = "00002902-0000-1000-8000-00805f9b34fb";

为什么它返回一个空值？

characteristic.getUuid()返回正确的值.

Answer 1

似乎你的设备不支持这个0x2902 BluetoothGattDescriptor尝试查看你的所有描述符:

  for (BluetoothGattDescriptor descriptor:characteristic.getDescriptors()){
                    Log.e(TAG, "BluetoothGattDescriptor: "+descriptor.getUuid().toString());
                }

Answer 2

尝试这个：

public final BluetoothGattCallback btleGattCallback = new BluetoothGattCallback() {
 @Override
        public void onConnectionStateChange( BluetoothGatt gatt,int status,int newState) { 
           if (status == BluetoothGatt.GATT_SUCCESS && newState ==   BluetoothProfile.STATE_CONNECTED) {
                    discoverServices();
           }
        }
 @Override
        public void onServicesDiscovered(BluetoothGatt gatt,int status) {
           BluetoothGattService service =gatt.getService(UUIDS.SERVICE_UUID);
           BluetoothGattCharacteristic characteristic;
           characteristic = service.getCharacteristic(UUIDS.CHARACTERSTICS_UUID);
           BluetoothGattDescriptor descriptor=characteristic.getDescriptor(UUIDS.CONFIG_DESCRIPTOR);
        }  
}