Question

在蓝牙低功耗协议问题上苦苦挣扎。例如，设备具有服务，并且此服务包含包含描述符的特征。服务，特征和描述符的UUID事先不知道。我的问题是如何以我们知道某个UUID是一种服务/特征/描述符的方式获取它们的UUID？

BluetoothGatt.getServices()没有帮助，因为它将所有UUID一起返回，我们不知道哪一个属于该服务。我确定有一种方法可以拆分UUID。至少nRF Connect应用程序（您可以在Play商店中找到它）可以做到这一点。

Answer 1

我解决此问题的唯一方法是使用从ScanRecord检索到的ScanResult。 ScanRecord存储有关每个扫描设备的一些信息，包括服务＆＃39;的UUID。通过ScanRecord方法启动扫描后，我们可以访问initScanning()对象，并在onScanResult()中返回任何结果：

List<UUID> serviceUUIDsList        = new ArrayList<>();
List<UUID> characteristicUUIDsList = new ArrayList<>();
List<UUID> descriptorUUIDsList     = new ArrayList<>();

private void initScanning(BluetoothLeScannerCompat bleScanner)
{
    bleScanner.startScan(getScanCallback());
}

private ScanCallback getScanCallback()
{
    return new ScanCallback()
    {
        @Override
        public void onScanResult(int callbackType, ScanResult scanResult)
        {
            super.onScanResult(callbackType, scanResult);
            serviceUUIDsList = getServiceUUIDsList(scanResult);
        }
    };
}

private List<UUID> getServiceUUIDsList(ScanResult scanResult)
{
    List<ParcelUuid> parcelUuids = scanResult.getScanRecord().getServiceUuids();

    List<UUID> serviceList = new ArrayList<>();

    for (int i = 0; i < parcelUuids.size(); i++)
    {
        UUID serviceUUID = parcelUuids.get(i).getUuid();

        if (!serviceList.contains(serviceUUID))
            serviceList.add(serviceUUID);
    }

    return serviceList;
}

因此，当我们知道服务UUID时，我们可以获得特征和描述符的UUID：

private void defineCharAndDescrUUIDs(BluetoothGatt bluetoothGatt)
{
    List<BluetoothGattService> servicesList = bluetoothGatt.getServices();

    for (int i = 0; i < servicesList.size(); i++)
    {
        BluetoothGattService bluetoothGattService = servicesList.get(i);

        if (serviceUUIDsList.contains(bluetoothGattService.getUuid()))
        {
            List<BluetoothGattCharacteristic> bluetoothGattCharacteristicList = bluetoothGattService.getCharacteristics();

            for (BluetoothGattCharacteristic bluetoothGattCharacteristic : bluetoothGattCharacteristicList)
            {
                characteristicUUIDsList.add(bluetoothGattCharacteristic.getUuid());
                List<BluetoothGattDescriptor> bluetoothGattDescriptorsList = bluetoothGattCharacteristic.getDescriptors();

                for (BluetoothGattDescriptor bluetoothGattDescriptor : bluetoothGattDescriptorsList)
                {
                    descriptorUUIDsList.add(bluetoothGattDescriptor.getUuid());
                }
            }
        }
    }
}

我希望，我也可以帮助其他会遇到类似问题的人。

Answer 2

此处列出了所有可用的特征：https://www.bluetooth.com/specifications/gatt/characteristics

现在您可以浏览UUID列表并与它们进行比较。这是一个包含其中一些的类：

// All BLE characteristic UUIDs are of the form:
// 0000XXXX-0000-1000-8000-00805f9b34fb
// The assigned number for the Heart Rate Measurement characteristic UUID is
// listed as 0x2A37, which is how the developer of the sample code could arrive at:
// 00002a37-0000-1000-8000-00805f9b34fb
public static class Characteristic {
    final static public UUID HEART_RATE_MEASUREMENT   = UUID.fromString("00002a37-0000-1000-8000-00805f9b34fb");
    final static public UUID CSC_MEASUREMENT          = UUID.fromString("00002a5b-0000-1000-8000-00805f9b34fb");
    final static public UUID MANUFACTURER_STRING      = UUID.fromString("00002a29-0000-1000-8000-00805f9b34fb");
    final static public UUID MODEL_NUMBER_STRING      = UUID.fromString("00002a24-0000-1000-8000-00805f9b34fb");
    final static public UUID FIRMWARE_REVISION_STRING = UUID.fromString("00002a26-0000-1000-8000-00805f9b34fb");
    final static public UUID APPEARANCE               = UUID.fromString("00002a01-0000-1000-8000-00805f9b34fb");
    final static public UUID BODY_SENSOR_LOCATION     = UUID.fromString("00002a38-0000-1000-8000-00805f9b34fb");
    final static public UUID BATTERY_LEVEL            = UUID.fromString("00002a19-0000-1000-8000-00805f9b34fb");
    final static public UUID CLIENT_CHARACTERISTIC_CONFIG = UUID.fromString("00002902-0000-1000-8000-00805f9b34fb");
}

然后，当您从gatt回调中收到特征时，尝试检查（针对列表）它的特征：

private final BluetoothGattCallback mGattCallback = new BluetoothGattCallback() {
    ...
    @Override
    public void onCharacteristicRead(BluetoothGatt gatt,
                                     BluetoothGattCharacteristic characteristic,
                                     int status) {
        if (status == BluetoothGatt.GATT_SUCCESS) {
            getCharacteristicValue(characteristic);
        }
    }

    @Override
    public void onCharacteristicChanged(BluetoothGatt gatt,
                                        BluetoothGattCharacteristic characteristic) {
        getCharacteristicValue(characteristic);
    }
}

private void getCharacteristicValue(BluetoothGattCharacteristic characteristic) {
    if(characteristic.getUuid().equals(Characteristic.HEART_RATE_MEASUREMENT)) {
        if (mType == Accessory.Type.HRM && mBtLeGattServiceHeartrate != null) {
            mBtLeGattServiceHeartrate.onCharacteristicChanged(mContext, BtLeDevice.this, characteristic);
        }
    }
}

希望这有帮助。

蓝牙低功耗（BLE） - 如何分别获取服务，特性和描述符的UUID

2 个答案: