What is the proper method for reading a GATT characteristic in Android?

问题

In attempting to read the value of a Bluetooth Low-Energy GATT characteristic in the Android API 18, I came across the following dilemma: What is the proper way to retrieve the value stored in a characteristic? And at which level of the stack should this action take place?

In conducting my own research, I stumbled upon what I understand are two possible methods:

• BluetoothGatt.readCharacteristic(BluetoothGattCharacteristic characteristic)

• BluetoothGattCharacteristic.getValue()

  public void onClick(View v){        
      byteValue = mBTValueCharacteristic.getValue();
      if ((byteValue[0] & 0x01) == 1)
          byteValue[0] = 0x00;
      else
          byteValue[0] = 0x01;
  
      mBTValueCharacteristic.setValue(byteValue);
      mBTGatt.writeCharacteristic(mBTValueCharacteristic);
  }
  

Above is the original code which led me to this issue. In it, I attempt to read the value of a characteristic, and simply toggle its state using a button.

回答1:

BluetoothGatt.readCharacteristic(BluetoothGattCharacteristic characteristic)

This function is updating your BluetoothGattCharacteristic object (on your Android device) using characteristic value from the Bluetooth .

BluetoothGattCharacteristic.getValue()

This function is just a getter function of the BluetoothGattCharacteristic object. There is not any transaction between android and the bluetooth device.

来源：https://stackoverflow.com/questions/20014078/what-is-the-proper-method-for-reading-a-gatt-characteristic-in-android