好的，这就是我几天来一直在努力弄清楚的问题。我们在 Windows Phone 7 上有一个应用程序，其中电话加入多播组，然后向该组发送和接收消息以相互交谈。注意 - 这是电话对电话的通信。

现在，我正在尝试将此应用程序移植到 Windows Phone 8 - 使用 Visual Studio 2012 中的“转换为 Phone 8”功能 - 到目前为止一切顺利。直到我尝试测试电话到电话的通信。手机似乎可以很好地加入该组，并且可以正常发送数据报。他们甚至会收到他们发送给群组的消息 - 然而，没有手机会收到来自另一部手机的消息。

这是我页面后面的示例代码:

// Constructor
public MainPage()
{
    InitializeComponent();
}

// The address of the multicast group to join.
// Must be in the range from 224.0.0.0 to 239.255.255.255
private const string GROUP_ADDRESS = "224.0.1.1";

// The port over which to communicate to the multicast group
private const int GROUP_PORT = 55562;

// A client receiver for multicast traffic from any source
UdpAnySourceMulticastClient _client = null;

// Buffer for incoming data
private byte[] _receiveBuffer;

// Maximum size of a message in this communication
private const int MAX_MESSAGE_SIZE = 512;

private void PhoneApplicationPage_Loaded(object sender, RoutedEventArgs e)
{
    _client = new UdpAnySourceMulticastClient(IPAddress.Parse(GROUP_ADDRESS), GROUP_PORT);
    _receiveBuffer = new byte[MAX_MESSAGE_SIZE];

    _client.BeginJoinGroup(
        result =>
        {
            _client.EndJoinGroup(result);
            _client.MulticastLoopback = true;
            Receive();
        }, null);
}

private void SendRequest(string s)
{
    if (string.IsNullOrWhiteSpace(s)) return;

    byte[] requestData = Encoding.UTF8.GetBytes(s);

    _client.BeginSendToGroup(requestData, 0, requestData.Length,
        result =>
        {
            _client.EndSendToGroup(result);
            Receive();
        }, null);
}

private void Receive()
{
    Array.Clear(_receiveBuffer, 0, _receiveBuffer.Length);
    _client.BeginReceiveFromGroup(_receiveBuffer, 0, _receiveBuffer.Length,
        result =>
        {
            IPEndPoint source;

            _client.EndReceiveFromGroup(result, out source);

            string dataReceived = Encoding.UTF8.GetString(_receiveBuffer, 0, _receiveBuffer.Length);

            string message = String.Format("[{0}]: {1}", source.Address.ToString(), dataReceived);
            Log(message, false);

            Receive();
        }, null);
}

private void Log(string message, bool isOutgoing)
{
    if (string.IsNullOrWhiteSpace(message.Trim('\0')))
    {
        return;
    }

    // Always make sure to do this on the UI thread.
    Deployment.Current.Dispatcher.BeginInvoke(
    () =>
    {
        string direction = (isOutgoing) ? ">> " : "<< ";
        string timestamp = DateTime.Now.ToString("HH:mm:ss");
        message = timestamp + direction + message;
        lbLog.Items.Add(message);

        // Make sure that the item we added is visible to the user.
        lbLog.ScrollIntoView(message);
    });

}

private void btnSend_Click(object sender, RoutedEventArgs e)
{
    // Don't send empty messages.
    if (!String.IsNullOrWhiteSpace(txtInput.Text))
    {
        //Send(txtInput.Text);
        SendRequest(txtInput.Text);
    }
}

private void btnStart_Click(object sender, RoutedEventArgs e)
{
    SendRequest("start now");
}

为了简单地测试 UDP 堆栈，我从 MSDN 上下载了样本 here我在一对 Windows Phone 7 设备上对此进行了测试，它按预期工作。然后我转换到 Windows Phone 8 并部署到我的手机上，设备似乎再次启动连接，用户可以输入他们的名字。但是，这些设备同样无法看到其他设备或与其他设备通信。

最后，我使用新的 DatagramSocket 实现实现了一个简单的通信测试，我再次看到启动成功，但没有设备间通信。

这与使用数据报套接字实现的页面隐藏代码相同:

// Constructor
public MainPage()
{
    InitializeComponent();
}

// The address of the multicast group to join.
// Must be in the range from 224.0.0.0 to 239.255.255.255
private const string GROUP_ADDRESS = "224.0.1.1";

// The port over which to communicate to the multicast group
private const int GROUP_PORT = 55562;

private DatagramSocket socket = null;

private void Log(string message, bool isOutgoing)
{
    if (string.IsNullOrWhiteSpace(message.Trim('\0')))
        return;

    // Always make sure to do this on the UI thread.
    Deployment.Current.Dispatcher.BeginInvoke(
    () =>
    {
        string direction = (isOutgoing) ? ">> " : "<< ";
        string timestamp = DateTime.Now.ToString("HH:mm:ss");
        message = timestamp + direction + message;
        lbLog.Items.Add(message);

        // Make sure that the item we added is visible to the user.
        lbLog.ScrollIntoView(message);
    });
}

private void btnSend_Click(object sender, RoutedEventArgs e)
{
    // Don't send empty messages.
    if (!String.IsNullOrWhiteSpace(txtInput.Text))
    {
        //Send(txtInput.Text);
        SendSocketRequest(txtInput.Text);
    }
}

private void PhoneApplicationPage_Loaded(object sender, RoutedEventArgs e)
{
    socket = new DatagramSocket();
    socket.MessageReceived += socket_MessageReceived;

    try
    {
        // Connect to the server (in our case the listener we created in previous step).
        await socket.BindServiceNameAsync(GROUP_PORT.ToString());
        socket.JoinMulticastGroup(new Windows.Networking.HostName(GROUP_ADDRESS));
        System.Diagnostics.Debug.WriteLine(socket.ToString());
    }
    catch (Exception exception)
    {
        throw;
    }
}

private async void SendSocketRequest(string message)
{
    // Create a DataWriter if we did not create one yet. Otherwise use one that is already cached.
    //DataWriter writer;
    var stream = await socket.GetOutputStreamAsync(new Windows.Networking.HostName(GROUP_ADDRESS), GROUP_PORT.ToString());
    //writer = new DataWriter(socket.OutputStream);
    DataWriter writer = new DataWriter(stream);

    // Write first the length of the string as UINT32 value followed up by the string. Writing data to the writer will just store data in memory.
   // stream.WriteAsync(
    writer.WriteString(message);

    // Write the locally buffered data to the network.
    try
    {
        await writer.StoreAsync();
        Log(message, true);
        System.Diagnostics.Debug.WriteLine(socket.ToString());
    }
    catch (Exception exception)
    {
        throw;
    }
    finally
    {
        writer.Dispose();
    }
}

void socket_MessageReceived(DatagramSocket sender, DatagramSocketMessageReceivedEventArgs args)
{
    try
    {
        uint stringLength = args.GetDataReader().UnconsumedBufferLength;
        string msg = args.GetDataReader().ReadString(stringLength);

        Log(msg, false);
    }
    catch (Exception exception)
    {
        throw;
    }
}

昨晚我 Handlebars 机带回家在我的家庭无线网络上测试它们，结果很低，我发现我的设备通信成功了。

回顾一下 - 我的旧版 Windows Phone 7 代码在我的工作网络上运行良好。 Windows Phone 8 的端口(没有实际代码更改)不发送设备间通信。此代码确实适用于我的家庭网络。代码在附加调试器的情况下运行，并且在执行期间的任何地方都没有错误或异常的迹象。

我使用的手机是:

Windows Phone 7 - 诺基亚 Lumia 900 (* 2)、诺基亚 Lumia 800 (* 3) Windows Phone 8 - 诺基亚 Lumia 920 (* 1)、诺基亚 Limia 820 (* 2)

这些都运行最新的操作系统，并且处于开发者模式。 开发环境为Windows 8 Enterprise运行Visual Studio 2012 Professional

关于工作无线网络，我不能告诉你太多 - 除了 Phone 7 设备没有问题。

至于我使用的家庭无线网络，那只是一个基本的 BT 宽带路由器，没有改变任何“开箱即用”设置。

显然这两个网络的配置方式存在问题，但 Windows Phone 8 实现 UDP 消息的方式也存在非常明显的问题。

任何意见都将不胜感激，因为这让我现在很生气。

最佳答案

我注意到你使用了环回。我认为这意味着当您从客户发送消息时，您也会收到您发送的消息。这意味着您的接收处理程序将触发。它具有以看似非线程安全的方式清除接收缓冲区的效果。尝试在您的接收方法中放置一些 try catch 并查看是否发生了任何不愉快的事情，但您可能在任何情况下都不使用共享接收缓冲区。

关于c# - Windows Phone 8 上的 UDP 多播组，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/13528262/