我在过去几天一直在努力解决一个问题，但是我似乎无法让它正常工作。
我有多个客户端连接到服务器，服务器需要保留已连接客户端的列表，如果客户端断开连接，则将其从列表中删除，我有一点正常工作。
一旦客户端连接，服务器可以通过发送客户端以2字节数据响应的几个字节的数据来调用客户端以获取有关其状态的一些信息。根据此响应，服务器将完成许多不同任务中的任何一个。
我有同步工作，但现在我正在尝试使函数异步，我正在遇到一个问题。我可以告诉我的功能，在客户端响应并返回错误数据之前，请求客户端的信息完成，如果我打印从客户端收到的数据，我可以看到它是正确的信息。
这是我第一次使用异步函数和连接，所以我很可能完全错了，我已经查看了很多示例代码，但我似乎找到了任何可以解决我的问题。< / p>
这就是我现在所拥有的：
'create the collection instance to store connected clients
Private clients As New List(Of TcpClient)
'declare a variable to hold the listener instance
Private listener As TcpListener
'declare a variable to hold the cancellation token source instance
Private tokenSource As CancellationTokenSource
Private recvTsk As Task
Private Rreply As New List(Of Byte)
Private Async Sub startTCPListenerServer()
'get port from ini file
Dim netPort = SettingsIniFile.GetString("Setup", "NetworkPort", "")
While True
'create a new cancellation token source instance
tokenSource = New CancellationTokenSource
'create a new listener instance bound to the desired address and port
listener = New TcpListener(IPAddress.Any, netPort)
'start the listener
listener.Start()
While True
Try
Dim client As TcpClient = Await listener.AcceptTcpClientAsync
clients.Add(client)
Dim clientIP As String = client.Client.RemoteEndPoint.ToString
ListBox1.Items.Add(clientIP)
Try
'begin reading from the client's data stream
Using stream As NetworkStream = client.GetStream
Dim buffer(client.ReceiveBufferSize - 1) As Byte
Dim read As Integer = 1
'if read is 0 client has disconnected
While read > 0
recvTsk = New Task(Sub()
For i = 0 To read - 1
'data recived at this point is correct
Rreply.Add(buffer(i))
Next
End Sub, tokenSource.Token)
read = Await stream.ReadAsync(buffer, 0, buffer.Length, tokenSource.Token)
recvTsk.Start()
End While
'client gracefully closed the connection on the remote end
End Using
Catch ocex As OperationCanceledException
'the expected exception if this routines's async method calls honor signaling of the cancelation token
'*NOTE: NetworkStream.ReadAsync() will not honor the cancelation signal
Catch odex As ObjectDisposedException
'server disconnected client while reading
Catch ioex As IOException
'client terminated (remote application terminated without socket close) while reading
Finally
'ensure the client is closed - this is typically a redundant call, but in the
'case of an unhandled exception it may be necessary
'remove the client from the list of connected clients
clients.Remove(client)
client.Close()
ListBox1.Items.Remove(clientIP)
'remove the client's task from the list of running tasks
'clientTasks.Remove(client.Task)
End Try
Catch odex As ObjectDisposedException
'listener stopped, so server is shutting down
Exit While
End Try
End While
For i As Integer = clients.Count - 1 To 0 Step -1
clients(i).Close()
Next
tokenSource.Dispose()
End While
'signal any processing of current clients to cancel (if listening)
tokenSource.Cancel()
'abort the current listening operation/prevent any new connections
listener.Stop()
'End If
End Sub
Async Function sendToPod(message() As Byte, podNum As Integer) As Task(Of Byte)
If clients.Count = 0 Then
Else
Dim podIP As String
'get ip address as string from ini file
podIP = SettingsIniFile.GetString("NetworkSettings", "Pod" & podNum & "IP", "")
Dim currentClient As TcpClient = Nothing
For Each client As TcpClient In clients
Dim clientIP As String = (CType(client.Client.RemoteEndPoint, IPEndPoint).Address.ToString())
If clientIP = podIP Then
currentClient = client
End If
Next
If currentClient IsNot Nothing Then
'get the current client, stream, and data to write
Dim stream As NetworkStream = currentClient.GetStream
Dim buffer() As Byte = message
'wait for the data to be sent to the remote
Await stream.WriteAsync(buffer, 0, buffer.Length)
recvTsk.Wait()
Return Rreply(1)
End If
End If
End Function
Private Async Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Try
Me.TextBox1.Text = Await sendToPod({"&HAB", "&HAD", "&HFF", "&HFF"}, 1)
Catch
End Try
End Sub
End Class