XamarinMulticastLock獲取不允許多播

我正在使用 Xamarin 創建一個 Android 應用程式。除其他事項外，此應用程式必須接收多播流。服務器發送正常，但我的應用程式沒有正確接收。如果我獲得了多播鎖，這就是我的研究表明我需要做的所有事情，我可以看到我有鎖，但應用程式仍然沒有收到資料。

var wifiManager = var wifiManager = (WifiManager)Application.Context.GetSystemService(Context.WifiService);
// Acquire the lock
if (wifiManager != null)
{
    // _lock is a private member WifiManager.MulticastLock _lock
    _lock = wifiManager.CreateMulticastLock("PiEar");

    if (_lock != null)
    {
        _lock.Acquire();
    } 
    else
    {
        Debug.WriteLine("Could not acquire multicast lock"); // Does not print, meaning I do acquire the lock (and _lock.IsHeld() returns true)
    }
} 
else 
{
    Debug.WriteLine("WifiManager is null"); // Does not print, meaning it is not null
}

如果我然后使用不同的應用程式MSniffer，它不僅會接收資料，而且還允許我的應用程式這樣做。我在嘗試獲取鎖時做錯了什么？

另外，我有以下權限：

• ACCESS_WIFI_STATE
• CHANGE_WIFI_STATE
• ACCESS_NETWORK_STATE
• 互聯網
• CHANGE_WIFI_MULTICAST_STATE

編輯 1：更多資訊

有問題的.cs頁面代碼如下。_receivedMessages是一個ListView，讓我可以直觀地看到接收到的資料。上面的代碼是line 2下面運行的。依賴服務中唯一的代碼是獲取鎖的代碼。

var service = DependencyService.Get<IMulticastLock>();
service.Acquire();
Task.Run(async () =>
{
    while (true)
    {
        try
        {
            var endpoint = new IPEndPoint(IPAddress.Parse("224.0.0.69"), 6666);
            var multicast = new UdpClient(endpoint);
            while (true)
            {

                var multicastBytes = await multicast.ReceiveAsync();
                var message = Encoding.UTF8.GetString(multicastBytes.Buffer);
                Debug.WriteLine($"Received: {message}");
                Device.BeginInvokeOnMainThread(() =>
                {
                    _receivedMessages.Add(message);
                });
            }
        }
        catch (Exception e)
        {
            Debug.WriteLine(e);
        }
    }
});

uj5u.com熱心網友回復：

1. 檢查 IP 地址和埠。

2. 您可以嘗試使用下面的代碼來了解如何創建和配置 UdpClient。

   public class MulticastUdpClient
   {
    UdpClient _udpclient;
    int _port;
    IPAddress _multicastIPaddress;
    IPAddress _localIPaddress;
    IPEndPoint _localEndPoint;
    IPEndPoint _remoteEndPoint;
   
    public MulticastUdpClient(IPAddress multicastIPaddress, int port, IPAddress localIPaddress = null)
    {
        // Store params
        _multicastIPaddress = multicastIPaddress;
        _port = port;
        _localIPaddress = localIPaddress;
        if (localIPaddress == null)
            _localIPaddress = IPAddress.Any;
   
        // Create endpoints
        _remoteEndPoint = new IPEndPoint(_multicastIPaddress, port);
        _localEndPoint = new IPEndPoint(_localIPaddress, port);
   
        // Create and configure UdpClient
        _udpclient = new UdpClient();
        // The following three lines allow multiple clients on the same PC
        _udpclient.ExclusiveAddressUse = false;
        _udpclient.Client.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
        _udpclient.ExclusiveAddressUse = false;
        // Bind, Join
        _udpclient.Client.Bind(_localEndPoint);
        _udpclient.JoinMulticastGroup(_multicastIPaddress, _localIPaddress);
   
        // Start listening for incoming data
        _udpclient.BeginReceive(new AsyncCallback(ReceivedCallback), null);
    }
   
    /// <summary>
    /// Send the buffer by UDP to multicast address
    /// </summary>
    /// <param name="bufferToSend"></param>
    public void SendMulticast(byte[] bufferToSend)
    {
        _udpclient.Send(bufferToSend, bufferToSend.Length, _remoteEndPoint);
    }
   
    /// <summary>
    /// Callback which is called when UDP packet is received
    /// </summary>
    /// <param name="ar"></param>
    private void ReceivedCallback(IAsyncResult ar)
    {
        // Get received data
        IPEndPoint sender = new IPEndPoint(0, 0);
        Byte[] receivedBytes = _udpclient.EndReceive(ar, ref sender);
   
        // fire event if defined
        if (UdpMessageReceived != null)
            UdpMessageReceived(this, new UdpMessageReceivedEventArgs() { Buffer = receivedBytes });
   
        // Restart listening for udp data packages
        _udpclient.BeginReceive(new AsyncCallback(ReceivedCallback), null);
    }
   
    /// <summary>
    /// Event handler which will be invoked when UDP message is received
    /// </summary>
    public event EventHandler<UdpMessageReceivedEventArgs> UdpMessageReceived;
   
    /// <summary>
    /// Arguments for UdpMessageReceived event handler
    /// </summary>
    public class UdpMessageReceivedEventArgs: EventArgs
    {
        public byte[] Buffer {get;set;}
    }
   
   }
   

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