了解 Android 低功耗蓝牙的特性

Question

我试图简单地从星系 S3 读取和写入 Hello World 到连接到虚拟串行端口的 blueradio 加密狗。但我得到

Unhandled exception: java.lang.NullPointerException

每当我打电话

gatt.readCharacteristic(characteristic);

我用它来定义特征

private static final UUID MY_UUID = UUID.fromString("00001801-0000-1000-8000-00805f9b34fb");
private static final UUID charUUID = UUID.fromString("00002a01-0000-1000-8000-00805f9b34fb");
characteristic = gatt.getService(MY_UUID).getCharacteristic(charUUID);

当我这样调用discoverServices()时我从LogCat获取的UUID

D/BluetoothGatt(7083): discoverServices() - device: EC:FE:7E:11:12:A4
D/BluetoothGatt(7083): onGetService() - Device=EC:FE:7E:11:12:A4 UUID=00001800-0000-1000-8000-00805f9b34fb
D/BluetoothGatt(7083): onGetService() - Device=EC:FE:7E:11:12:A4 UUID=00001801-0000-1000-8000-00805f9b34fb
D/BluetoothGatt(7083): onGetService() - Device=EC:FE:7E:11:12:A4 UUID=0000180f-0000-1000-8000-00805f9b34fb
D/BluetoothGatt(7083): onGetService() - Device=EC:FE:7E:11:12:A4 UUID=da2b84f1-6279-48de-bdc0-afbea0226079
D/BluetoothGatt(7083): onGetCharacteristic() - Device=EC:FE:7E:11:12:A4 UUID=00002a00-0000-1000-8000-00805f9b34fb
D/BluetoothGatt(7083): onGetCharacteristic() - Device=EC:FE:7E:11:12:A4 UUID=00002a01-0000-1000-8000-00805f9b34fb
D/BluetoothGatt(7083): onGetCharacteristic() - Device=EC:FE:7E:11:12:A4 UUID=00002a02-0000-1000-8000-00805f9b34fb
D/BluetoothGatt(7083): onGetCharacteristic() - Device=EC:FE:7E:11:12:A4 UUID=00002a03-0000-1000-8000-00805f9b34fb

这是我不确定我是否做对的地方我不知道如何为特征和服务获取正确的 UUID

Beloiw 是我完整的回调函数

private BluetoothGattCallback mGattCallback = new BluetoothGattCallback() {

    public void testFunction(BluetoothGatt gatt){
        Log.d(TAG, "In Test Function");
        gatt.readRemoteRssi();
        BluetoothGattCharacteristic characteristic;
        characteristic = gatt.getService(MY_UUID).getCharacteristic(charUUID);
        characteristic.setValue("Hello World");
        gatt.readCharacteristic(characteristic);
    }
     @Override
    public void onConnectionStateChange(BluetoothGatt gatt, int status,
            int newState) {


            gatt.discoverServices();


    }


@Override
public void onServicesDiscovered(BluetoothGatt gatt, int status) {
    Log.d(TAG, "Services Discovered: "+ status);
    //mHandler.sendMessage(Message.obtain(null, MSG_PROGRESS, "Enabling Sensors..."));
    /*
     * With services discovered, we are going to reset our state machine and start
     * working through the sensors we need to enable
     */
            testFunction(gatt);
}


public void     onCharacteristicChanged(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic){
    Log.d(TAG, "Characteristic Changed: "+ characteristic.getValue());
}

public void     onCharacteristicRead(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic, int status){
    Log.d(TAG, "Characteristic Read: "+ status);
}

public void     onCharacteristicWrite(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic, int status){
    Log.d(TAG, "Characteristic Write: "+ status);
}



public void     onDescriptorRead(BluetoothGatt gatt, BluetoothGattDescriptor descriptor, int status){
    Log.d(TAG, "Descriptor Read: "+ status);
}

public void     onDescriptorWrite(BluetoothGatt gatt, BluetoothGattDescriptor descriptor, int status){
    Log.d(TAG, "Descriptor Write: "+ status);
}

public void     onReadRemoteRssi(BluetoothGatt gatt, int rssi, int status){
    Log.d(TAG, "Read Rssi: "+ status);
}

public void     onReliableWriteCompleted(BluetoothGatt gatt, int status){
    Log.d(TAG, "Reliable Write: "+ status);
}


};

Answer 1

UUID 由 bluetooth.org 预定义，它定义了前缀，例如 00001800，最后一部分“0000-1000-8000-00805f9b34fb”是相同的。

在此处查看预定义的 UUID 列表。