从UWP获取TCP服务器上的实时数据（更新）

下面是一种基本上将数据发送到TCP Server的方法。

UPDATE BEGINS HERE: ////////////////////////////////// private string FormatValueByPresentation(IBuffer buffer, GattPresentationFormat format) { // BT_Code: For the purpose of this sample, this function converts only UInt32 and // UTF-8 buffers to readable text. It can be extended to support other formats if your app needs them. byte[] data; CryptographicBuffer.CopyToByteArray(buffer, out data); if (format != null) { if (format.FormatType == GattPresentationFormatTypes.UInt32 && data.Length >= 4) { return BitConverter.ToInt32(data, 0).ToString(); } else if (format.FormatType == GattPresentationFormatTypes.Utf8) { try { return Encoding.UTF8.GetString(data); } catch (ArgumentException) { return "(error: Invalid UTF-8 string)"; } } else { // Add support for other format types as needed. return "Unsupported format: " + CryptographicBuffer.EncodeToHexString(buffer); } } else if (data != null) { // We don't know what format to use. Let's try some well-known profiles, or default back to UTF-8. if (selectedCharacteristic.Uuid.Equals(GattCharacteristicUuids.HeartRateMeasurement)) { try { ///////LOOK HERE///// **string b = ParseHeartRateValue(data).ToString(); TrySend(b); //return "Heart Rate: " + ParseHeartRateValue(data).ToString(); return "Heart Rate: " + b;** } catch (ArgumentException) { return "Heart Rate: (unable to parse)"; } } else if (selectedCharacteristic.Uuid.Equals(GattCharacteristicUuids.BatteryLevel)) { try { // battery level is encoded as a percentage value in the first byte according to // https://www.bluetooth.com/specifications/gatt/viewer?attributeXmlFile=org.bluetooth.characteristic.battery_level.xml return "Battery Level: " + data[0].ToString() + "%"; } catch (ArgumentException) { return "Battery Level: (unable to parse)"; } } // This is our custom calc service Result UUID. Format it like an Int else if (selectedCharacteristic.Uuid.Equals(Constants.ResultCharacteristicUuid)) { return BitConverter.ToInt32(data, 0).ToString(); } // No guarantees on if a characteristic is registered for notifications. else if (registeredCharacteristic != null) { // This is our custom calc service Result UUID. Format it like an Int if (registeredCharacteristic.Uuid.Equals(Constants.ResultCharacteristicUuid)) { return BitConverter.ToInt32(data, 0).ToString(); } } else { try { return "Unknown format: " + Encoding.UTF8.GetString(data); } catch (ArgumentException) { return "Unknown format"; } } } else { return "Empty data received"; } return "Unknown format"; } ///////// END OF UPDATE ////// private async void TrySend(string data) { // Create the StreamSocket and establish a connection to the echo server. StreamSocket socket = new StreamSocket(); try { var streamSocket = new Windows.Networking.Sockets.StreamSocket(); { //The server hostname that we will be establishing a connection to. In this example, the server and client are in the same process. var hostName = new Windows.Networking.HostName("127.0.0.1"); await streamSocket.ConnectAsync((new Windows.Networking.HostName("127.0.0.1")), "9999"); // Send a request to the echo server. using (Stream outputStream = streamSocket.OutputStream.AsStreamForWrite()) { using (var streamWriter = new StreamWriter(outputStream)) { while (true) { await streamWriter.WriteLineAsync(data); await streamWriter.FlushAsync(); } //await streamWriter.WriteLineAsync(data); //await streamWriter.FlushAsync(); } } } } catch (Exception) { } } 

这是我的TCP服务器代码，它接收数据：

  public class EchoServer { public static void Main() { TcpListener listener = null; try { listener = new TcpListener(IPAddress.Parse("127.0.0.1"), 9999); listener.Start(); Console.WriteLine("TCP Server Has Started...."); while (true) { Console.WriteLine(" "); Console.WriteLine("Waiting for incoming client connections...."); Console.WriteLine(" "); Console.WriteLine("A message will display below once the client starts and establishes a connection "); TcpClient client = listener.AcceptTcpClient(); Console.WriteLine(" "); Console.WriteLine("Okay, Accepting Client connection now"); Console.WriteLine(" "); Console.WriteLine("Accepted new client connection....."); StreamReader reader = new StreamReader(client.GetStream()); StreamWriter writer = new StreamWriter(client.GetStream()); string s = string.Empty; while (!(s = reader.ReadLine()).Equals("Exit") || (s == null)) { Console.WriteLine("From client -> " + s); writer.WriteLine("From server -> " + s); writer.Flush(); } reader.Close(); writer.Close(); client.Close(); } } catch (Exception e) { Console.WriteLine(e); } finally { if (listener != null) { listener.Stop(); } } } } 

现在，我想要得到的数据是心率，它每两秒钟就会变化一次。 然而，在TCP服务器上，我只获得心率的第一个记录值，并且它不断重复而不是获得新的心率。

我在stackoverflow上看到了类似的post： UWP TCP连续接收数据

并且有人建议使用while循环，我在代码中可以看到。 我还应该怎么做？

谢谢

Answer 1

 while (true) { await streamWriter.WriteLineAsync(data); await streamWriter.FlushAsync(); } 

while（true）将继续重复，这意味着它将始终以其当前值发送’data’。 这是导致您的问题的原因。

在我看来，您应该在“TrySend”方法之外保持与TCP服务器的连接，并且仅使用此方法发送数据。 这样您就不需要使用此循环。

编辑：

试试这个 ：

 private async void CharacteristicReadButton_Click() { while(true) { // BT_Code: Read the actual value from the device by using Uncached. GattReadResult result = await selectedCharacteristic.ReadValueAsync(BluetoothCacheMode.Uncached); if (result.Status == GattCommunicationStatus.Success) { string formattedResult = FormatValueByPresentation(result.Value, presentationFormat); rootPage.NotifyUser($"Read result: {formattedResult}", NotifyType.StatusMessage); //string formattedResult = FormatValueByPresentation(result.Value, presentationFormat); //rootPage.NotifyUser($"Read result: {formattedResult}", NotifyType.StatusMessage); } else { rootPage.NotifyUser($"Read failed: {result.Status}", NotifyType.ErrorMessage); } } }