藍牙 Radio.StateChanged 事件觸發兩次

Question

我想在藍牙收音機打開或關閉時收聽。 為此，我只是獲得了默認收音機並訂閱了 StateChanged。

var bluetoothAdapter = await BluetoothAdapter.GetDefaultAsync();
var radio = await bluetoothAdapter.GetRadioAsync();
radio.StateChanged += Radio_StateChanged;

private void Radio_StateChanged(Windows.Devices.Radios.Radio sender, object args)
{
    Console.WriteLine(String.Format("Radio state changed {0} {1}", sender.Kind, sender.Name));
}

當我通過 Windows 藍牙設置更改藍牙 state 時，我得到了兩次 StateChanged 事件。

Output：

Radio state changed Bluetooth Bluetooth
Radio state changed Bluetooth Bluetooth

我將模塊與藍牙和 Wifi 放在一起。 我想也許這是原因。 然后我得到所有收音機Radio.GetRadiosAsync

radios = await Radio.GetRadiosAsync();
foreach (var r in radios)
{
    r.StateChanged += Radio_StateChanged;
}

Output：

Radio state changed Bluetooth Bluetooth
Radio state changed Bluetooth Bluetooth
Radio state changed WiFi Wi-Fi
Radio state changed WiFi Wi-Fi

這是預期的行為嗎？

更新。 我將 state 值添加到 output

Output：

Radio state changed Bluetooth Bluetooth Off
Radio state changed Bluetooth Bluetooth Off

Answer 1

這可能是Radio.StateChanged API 的錯誤。 我也面臨同樣的問題。 您可以通過檢查無線電 State 來最小化問題，如下所示：

public Radio BluetoothAdapter { get; set; }
public RadioState OldBluetoothState;
public RadioState NewBluetoothState;


IReadOnlyList<Radio> radios = await Radio.GetRadiosAsync();
BluetoothAdapter = radios.FirstOrDefault(radio => radio.Kind == RadioKind.Bluetooth);
if (BluetoothAdapter != null)
{
   OldBluetoothState = BluetoothAdapter.State;
   BluetoothAdapter.StateChanged += RadioBluetoothAdapter_StateChanged;
}

private void RadioBluetoothAdapter_StateChanged(Radio sender, object args)
{
  try
  {
    NewBluetoothState = sender.State;
    if (NewBluetoothState != OldBluetoothState)
    {
        OldBluetoothState = NewBluetoothState;

        if (sender.State == RadioState.Off)
        {
            //Application logic will goes here.
            Debug.WriteLine("Bluetooth has been turned off.");
        }
        else
        {
            //Application logic will goes here.
            Debug.WriteLine("Bluetooth has been turned on.");
        }
    }
  }
  catch (Exception ex)
  {
     Debug.WriteLine($"Exception has been occured: {ex.Message.ToString()}");
  }
}