从 UWP 获取 TCP 服务器上的实时数据(更新) [英] Get the live data on TCP server from UWP (UPDATED)
本文介绍了从 UWP 获取 TCP 服务器上的实时数据(更新)的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
下面是一种基本上将数据发送到 TCP 服务器的方法.
Below is one method that basically sends the data to TCP Server.
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)
{
}
}
这是我接收数据的 TCP 服务器代码:
And here is my TCP Server code that receives the data:
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，我想要获取的数据是心率，它每两秒变化一次.然而，在 TCP 服务器上，我只得到第一个记录的心率值，并且它不断重复而不是获得新的.
Now, the data I am trying to get are the heart rates and it changes every two seconds. However on TCP server I only get the first recorded value of a heart rate and it keeps repeating instead of getting new one.
我在 stackoverflow 上看到了类似的帖子:UWP TCP 连续接收数据
There is a similar post I saw here on stackoverflow : UWP TCP receive data continuously
有人建议使用 while 循环，正如您在代码中看到的那样.对于我该怎么做，还有其他建议吗?
and someone suggested to use while loop which I did as you can see in the code. Are there any other suggestions on what should I do?
谢谢
推荐答案
while (true)
{
await streamWriter.WriteLineAsync(data);
await streamWriter.FlushAsync();
}
while(true) 将不断重复，这意味着它将始终以其当前值发送数据".这就是导致您出现问题的原因.
The while(true) will keep repeating, meaning that it will always send 'data' at its current value. This is what causes your issue.
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.这样你就不需要使用这个循环了.
In my opinion, you should keep a connection to your TCP server open outside of your 'TrySend' method, and use this method only to send the data. This way you won't need to use this loop.
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);
}
}
}
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