Question

我正在编写一个简单的TCP服务器。我可以连接并向它发送消息，但我认为我在线程和调用方面存在一些问题，因为我无法将收到的消息添加到列表框中，尽管消息正确显示在msgbox中。

代码编译运行没有任何抱怨，所以我不知道我做错了什么。

任何人都可以帮助我吗？这段代码有什么问题？

这是主要课程：

Imports System
Imports System.Net
Imports System.Net.Sockets
Imports System.Threading
Imports System.Text
Imports System.IO


Public Class MC_main

    Dim Listener As New TcpListener(61100)
    Dim Client As New TcpClient
    Dim server_connections_cnt As Integer
    Dim do_exit As Boolean

    Private Sub MC_main_FormClosed(sender As Object, e As FormClosedEventArgs) Handles Me.FormClosed
        'MsgBox("Form closed")
        End
    End Sub

    Private Sub MC_main_FormClosing(sender As Object, e As FormClosingEventArgs) Handles Me.FormClosing
        'MsgBox("Form closing")
        do_exit = True
    End Sub


    Private Sub MC_main_Load(sender As Object, e As EventArgs) Handles MyBase.Load

        do_exit = False
        ' Create listener thread
        Dim ListenerThread As New Thread(New ThreadStart(AddressOf Listening))
        ListenerThread.Start()

    End Sub

    ' LISTENER THREAD
    Private Sub Listening()

        Dim clientSocket As TcpClient = Nothing

        Listener.Start()

        lstDebug_addItem("Server Started")  ' THIS IS ADDED TO THE LSTBOX
        server_connections_cnt = 0
        While (do_exit = False)
            clientSocket = Listener.AcceptTcpClient()
            server_connections_cnt += 1

            lstDebug_addItem("Client " + Convert.ToString(server_connections_cnt) + " started!")  ' THIS IS ADDED TO THE LSTBOX
            Dim wsCon As New handleWSconnection
            wsCon.startClient(clientSocket, Convert.ToString(server_connections_cnt))
        End While

        If Not IsNothing(clientSocket) Then
            clientSocket.Close()
        End If

        Listener.Stop()
    End Sub

    Public Sub lstDebug_addItem(msg As String)

        If lstDebug.InvokeRequired Then
            Me.Invoke(New lstBox_addItem_Delegate(AddressOf AddItemLstBox), Me.lstDebug, msg)
        Else
            ' ENTER HERE WHEN CALLED FROM THE OTHER CLASS
            MsgBox(msg)  ' THIS MESSAGEBOX SHOWS THE MESSAGE
            lstDebug.Items.Add("Message: " + msg)  ' THIS ITEM IS NOT ADDED TO THE lstDebug LISTBOX, WHY?
        End If
    End Sub


    Public Delegate Sub lstBox_addItem_Delegate(ByRef lstbox As ListBox, ByVal str As String)
    Public Sub AddItemLstBox(ByRef lstbox As ListBox, ByVal str As String)
        lstbox.Items.Add(str)
    End Sub
End Class

这是我处理新客户的类：

Imports System
Imports System.Net
Imports System.Net.Sockets
Imports System.Threading

Public Class handleWSconnection

    Dim WSocket As TcpClient
    Dim clNo As String

    Public Sub startClient(ByVal inWSocket As TcpClient, ByVal clineNo As String)
        Me.WSocket = inWSocket
        Me.clNo = clineNo
        Dim wsCon As New Thread(New ThreadStart(AddressOf wsConnection))
        wsCon.Start()
    End Sub

    Private Sub wsConnection()
        Dim bytesFrom(1024) As Byte
        Dim dataFromClient As String
        Dim sendBytes As [Byte]()
        Dim serverResponse As String
        Dim rCount As String
        Dim alive As Boolean

        alive = True

        While (alive)
            Try
                Dim myNetworkStream As NetworkStream = WSocket.GetStream()

                If myNetworkStream.CanRead Then
                    Dim myReadBuffer(1024) As Byte
                    Dim numberOfBytesRead As Integer = 0

                    ' Incoming message may be larger than the buffer size.
                    Do
                        numberOfBytesRead = myNetworkStream.Read(myReadBuffer, 0, myReadBuffer.Length)
                        dataFromClient = System.Text.Encoding.ASCII.GetString(myReadBuffer)
                        MC_main.lstDebug_addItem(dataFromClient) 'THIS IS THE CALL THAT DOES NOTHING.. I WANT TO ADD THE RECEIVED STRING TO THE LISTBOX
                    Loop While myNetworkStream.DataAvailable
                Else
                    MsgBox("Sorry.  You cannot read from this NetworkStream.")
                End If
            Catch ex As Exception
                MsgBox("Exception: " + ex.ToString)
                alive = False
            End Try
        End While
    End Sub
End Class

Thnks！

Answer 1

从MSDN page on the ListBox开始，试试这个：

// Shutdown the painting of the ListBox as items are added.
lstDebug.BeginUpdate();

lstDebug.Items.Add("Message: " + msg);

// Allow the ListBox to repaint and display the new items.
lstDebug.EndUpdate();

VB .NET简单服务器示例未在列表框中显示接收的数据

1 个答案: