c# – Windows UWP蓝牙应用程序,即使在关闭电源时也会显示扫描设备

我正在开发一个使用蓝牙连接到不同设备的UWP应用程序.

我的问题是,已配对或先前发现的某些设备显示在我的设备列表中,即使它们已关闭或未在范围内.

根据我的理解,属性System.Devices.Aep.IsPresent可用于过滤掉当时不可用的缓存设备,但即使我知道设备无法访问,我仍然会获得该属性的“True”.

关于如何解决这个问题的任何想法？

建立

string[] requestedProperties = { "System.Devices.Aep.DeviceAddress", "System.Devices.Aep.IsConnected", "System.Devices.Aep.IsPresent", "System.Devices.Aep.ContainerId", "System.Devices.Aep.DeviceAddress", "System.Devices.Aep.Manufacturer", "System.Devices.Aep.ModelId", "System.Devices.Aep.ProtocolId", "System.Devices.Aep.SignalStrength"};
        _deviceWatcher = Deviceinformation.CreateWatcher("{REMOVED, NOT IMPORTANT}", requestedProperties, DeviceinformationKind.AssociationEndpoint);
        _deviceWatcher.Added += DeviceAdded;
        _deviceWatcher.Updated += DeviceUpdated;
        _deviceWatcher.Removed += DeviceRemoved;
        _deviceWatcher.EnumerationCompleted += DeviceEnumerationCompleted;

添加设备时的回调

这是现在总是如此

private void DeviceAdded(DeviceWatcher sender, Deviceinformation deviceInfo)
{
    Device device = new Device(deviceInfo);
    bool isPresent = (bool)deviceInfo.Properties.Single(p => p.Key == "System.Devices.Aep.IsPresent").Value;
    Debug.WriteLine("*** Found device " + deviceInfo.Id + " / " + device.Id + ", " + "name: " + deviceInfo.Name + " ***");
    Debug.WriteLine("RSSI = " + deviceInfo.Properties.Single(d => d.Key == "System.Devices.Aep.SignalStrength").Value);
    Debug.WriteLine("Present: " + isPresent);
    var RSSi = deviceInfo.Properties.Single(d => d.Key == "System.Devices.Aep.SignalStrength").Value;
    if (RSSi != null)
        device.RSSi = int.Parse(RSSi.ToString());
    if (discoveredDevices.All(x => x.Id != device.Id) && isPresent)
    {
        discoveredDevices.Add(device);
        Devicediscovered(this, new DevicediscoveredEventArgs(device));
    }
}

解决方法:

查看Microsoft Bluetooth LE Explorer source code of GattSampleContext.您需要获取属性：System.Devices.Aep.IsConnected,System.Devices.Aep.Bluetooth.Le.IsConnectable并仅过滤可连接的设备.请注意,在调用DeviceWatcher.Updated事件后,设备可能变为可连接.所以你必须保留一些未使用的设备.

例如.我的IsConnactable过滤方法是：

private static bool IsConnectable(Deviceinformation deviceinformation)
{
    if (string.IsNullOrEmpty(deviceinformation.Name))
        return false;
    // Let's make it connectable by default, we have error handles in case it doesn't work
    bool isConnectable = (bool?)deviceinformation.Properties["System.Devices.Aep.Bluetooth.Le.IsConnectable"] == true;
    bool isConnected = (bool?)deviceinformation.Properties["System.Devices.Aep.IsConnected"] == true;
    return isConnectable || isConnected;
}