聊天系统有一种还是两种方式？

Question

我正在尝试构建一个简单的聊天客户端/软件（全部包含在可执行文件中），它从端口 5900 开始监听，当客户端连接到该端口时，聊天就建立了。

问题是只有客户端可以与服务器聊天，服务器无法回复客户端，因为连接以一种方式工作。

当客户端建立连接时，我尝试从“服务器”连接到客户端，但系统崩溃警告我该端口已在使用中。

这是我的代码：（以一种方式工作）

Imports System.Net.Sockets
Imports System.Text
Imports System.Reflection

Public Class frmComplete
  Dim Data As Integer
  Dim Message As String

  Private sServer As TcpListener
  Private sClient As New TcpClient

  Private cServer As TcpListener
  Private cClient As New TcpClient
  Private cNick As String

  Dim BufferSize(1024) As Byte

  Private Delegate Sub MessageDelegate(ByVal Message As String)

Private Sub frmComplete_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
    srvListen(5900)
    btnSend.Enabled = False
End Sub

Private Sub OnServerConnect(ByVal AR As IAsyncResult)
    sClient = sServer.EndAcceptTcpClient(AR)

    sClient.GetStream.BeginRead(BufferSize, 0, BufferSize.Length, AddressOf OnRead, Nothing)

    My.Computer.Audio.Play(Application.StartupPath & "\Connected.wav", AudioPlayMode.Background)
End Sub

Private Sub OnRead(ByVal AR As IAsyncResult)
    Data = sClient.GetStream.EndRead(AR)
    Message = Encoding.ASCII.GetString(BufferSize, 0, Data)

    Dim Args As Object() = {Message}
    Me.Invoke(New MessageDelegate(AddressOf PrintMessage), Args)

    sClient.GetStream.BeginRead(BufferSize, 0, BufferSize.Length, AddressOf OnRead, Nothing)
End Sub

Private Sub PrintMessage(ByVal Message As String)
    Try
        txtChat.Text = txtChat.Text & Message & vbCrLf
        My.Computer.Audio.Play(Application.StartupPath & "\Message.wav", AudioPlayMode.Background)
    Catch ex As Exception
        MsgBox(ex.Message, MsgBoxStyle.Critical)
    End Try
End Sub

Private Sub srvListen(ByVal port As Integer)
    Try
        sServer = New TcpListener(System.Net.IPAddress.Any, 5900)
        sServer.Start()

        'THIS WILL RAISE THE EVENT WHEN A CLIENT IS CONNECTED
        sServer.BeginAcceptTcpClient(AddressOf OnServerConnect, Nothing)
    Catch ex As Exception
        MsgBox(ex.Message, MsgBoxStyle.Critical)
    End Try
End Sub



Private Sub txtMessage_KeyDown(ByVal sender As System.Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles txtMessage.KeyDown
    'FIXME (SOUND T_T)
    If e.KeyCode = Keys.Enter Then
        SendMessage(cNick & ":" & txtMessage.Text)
    End If
End Sub

Private Sub btnConnect_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnConnect.Click
    ConnectToServer(txtIP.Text)
    cNick = txtNickname.Text

    txtNickname.Enabled = False
    txtIP.Enabled = False
    btnConnect.Enabled = False
End Sub

Private Sub ConnectToServer(ByVal ipadress As String)
    Try
        cClient.BeginConnect(ipadress, 5900, AddressOf OnClientConnect, Nothing)
    Catch ex As Exception
        MsgBox(ex.Message)
    End Try
End Sub

Private Sub OnClientConnect(ByVal AR As IAsyncResult)
    Try
        cClient.EndConnect(AR)
    Catch ex As Exception
        MsgBox(ex.Message)
    End Try
End Sub

Private Sub btnSend_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSend.Click
    If Not String.IsNullOrEmpty(txtMessage.Text) Then

        txtChat.Text = txtChat.Text & "Me:" & txtMessage.Text & vbCrLf
        SendMessage(cNick & ":" & txtMessage.Text)

    End If
End Sub

Private Sub SendMessage(ByVal message As String)
    If cClient.Connected = True Then
        Dim Writer As New IO.StreamWriter(cClient.GetStream)
        Writer.Write(message)
        Writer.Flush()
    End If

    txtMessage.Text = ""
End Sub

Private Sub SendCommand(ByVal command As String)
    If cClient.Connected = True Then
        Dim Writer As New IO.StreamWriter(cClient.GetStream)
        Writer.Write(command)
        Writer.Flush()
    End If

    txtMessage.Text = ""
End Sub

Private Sub txtMessage_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles txtMessage.TextChanged
    If Not String.IsNullOrEmpty(txtMessage.Text) Then
        btnSend.Enabled = True
    Else
        btnSend.Enabled = False
    End If
End Sub
End Class

我该怎么办？使用两个端口？一个写一个读？如果我需要将多个客户端连接到一个用户？ （记住同一个 exe 是服务器/客户端）

请帮帮我=(

Answer 1

您没有读取从服务器返回的任何数据。您会注意到在调用 BeginRead 的 OnServerConnect 方法中 - 您还需要在 OnClientConnect 方法中为您的客户端执行此操作，否则您将获得单向通信。也许这就是您看不到任何数据的原因？

我猜，当您的服务器将数据发送回客户端时，您不会收到硬错误，只是没有数据。

浏览一下您的代码，我注意到您的客户端和服务器同时拥有一个 TcpClient 和 TcpListener。你不需要这个。您的 SERVER 将是 TcpListener，而您的 CLIENT 将是 TcpClient。通过询问您是否应该在与服务器不同的端口上重新连接，您正在缩短自己对 TCP 连接的真正含义。一旦你的 TcpClient 连接到 TcpServer，你的连接就建立了。无需进一步尝试连接。

您的客户端代码应该类似于：

Private Sub OnClientConnect(ByVal AR As IAsyncResult) 
    Try 
        cClient.EndConnect(AR)
     sServer.GetStream.BeginRead(BufferSize, 0, BufferSize.Length, AddressOf OnClientRead, Nothing)
    Catch ex As Exception 
        MsgBox(ex.Message) 
    End Try 
End Sub 


Private Sub OnClientRead(ByVal AR As IAsyncResult) 
    Data = sServer.GetStream.EndRead(AR) 
    Message = Encoding.ASCII.GetString(BufferSize, 0, Data) 

    Dim Args As Object() = {Message} 
    Me.Invoke(New MessageDelegate(AddressOf PrintMessage), Args) 

    sServer.GetStream.BeginRead(BufferSize, 0, BufferSize.Length, AddressOf OnClientRead, Nothing) 
End Sub