vb.net - 调用 webserver 类时编程崩溃

Question

提前感谢您的帮助。

我在我的 VB.net 应用程序中运行基于套接字的网络服务器。每当我在程序中调用类时（即加载主应用程序时），程序就会崩溃。

你能帮我吗？

---

Private Sub Login_Load(sender As System.Object, e As System.EventArgs) Handles    MyBase.Load
    AcceptButton = SubmitLogin
    Dim CurrDate As Date
    CurrDate = DateValue(Now)
    Label3.Text = CurrDate
    OpenConnection()
    username.Text = ""
    password.Text = ""

    server.serve()

End Sub

---

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

Public Module Webserver
Public server As WebServer = New WebServer
Sub Main()
End Sub

Public Class WebServer
    Private tcpListener As System.Net.Sockets.TcpListener
    Private clientSocket As System.Net.Sockets.Socket
    ' Set WWW Root Path
    Dim rootPath As String = "\\ndrive.rdg.ac.uk\mv003237\My Documents\Business Programming Coursework 2\Webserver\"
    ' Set default page
    Dim defaultPage As String = "index.html"
    Public Sub serve()
        Dim hostName As String = Dns.GetHostName()
        Dim serverIP As IPAddress = Dns.GetHostEntry(hostName).AddressList(4)
        Dim Port As String = "8080"
        tcpListener = New TcpListener(serverIP, Int32.Parse(Port))
        tcpListener.Start()

        While (True)
            clientSocket = tcpListener.AcceptSocket()
            ' Socket Information
            Dim clientInfo As IPEndPoint = CType(clientSocket.RemoteEndPoint, IPEndPoint)

            ProcessRequest()
        End While
    End Sub

    Protected Sub ProcessRequest()
        Dim recvBytes(1024) As Byte
        Dim htmlReq As String = Nothing
        Dim bytes As Int32

        ' Receive HTTP Request from Web Browser
        'Some browsers send empty requests sometimes, in addition to the real requests.
        Dim tries As Integer = 10
        While tries > 0
            bytes = clientSocket.Receive(recvBytes, 0, clientSocket.Available, SocketFlags.None)
            If bytes > 0 Then
                tries = 0
            Else
                tries = tries - 1

                'Pause for a moment (50 milliseconds) to wait for the next request
                Thread.Sleep(50)
            End If
        End While

        htmlReq = Encoding.ASCII.GetString(recvBytes, 0, bytes)


        Dim strArray() As String
        Dim strRequest As String

        strArray = htmlReq.Trim.Split(" ")

        ' Determine the HTTP method (GET only)
        If strArray(0).Trim().ToUpper.Equals("GET") Then
            strRequest = strArray(1).Trim

            If (strRequest.StartsWith("/")) Then
                strRequest = strRequest.Substring(1)
            End If

            If (strRequest.EndsWith("/") Or strRequest.Equals("")) Then
                strRequest = strRequest & defaultPage
            End If

            strRequest = rootPath & strRequest
            sendHTMLResponse(strRequest)

        ElseIf strArray(0).Trim() <> "" Then ' Not HTTP GET method
            strRequest = rootPath & "400.html"
            sendHTMLResponse(strRequest)
        End If

        clientSocket.Close()
    End Sub

    ' Send HTTP Response
    Private Sub sendHTMLResponse(ByVal httpRequest As String)
        ' Get the file content of HTTP Request
        Dim streamReader As FileStream
        Dim response As String
        If Not File.Exists(httpRequest) Then
            httpRequest = rootPath & "404.html" 'should really be 404.html
            response = "404 Not Found"
        Else
            response = "200 OK"
        End If
        streamReader = New FileStream(httpRequest, IO.FileMode.Open, IO.FileAccess.Read)
        Dim len As Integer = streamReader.Length
        Dim strBuff(len) As Byte
        streamReader.Read(strBuff, 0, len)
        streamReader.Close()
        streamReader = Nothing

        ' Set HTML Header
        Dim htmlHeader As String = _
          "HTTP/1.0 " & response & ControlChars.CrLf & _
          "Server: WebServer 1.0" & ControlChars.CrLf & _
          "Content-Length: " & len & ControlChars.CrLf & _
          "Content-Type: " & getContentType(httpRequest) & _
           ControlChars.CrLf & ControlChars.CrLf

        ' The content Length of HTML Header
        Dim headerByte() As Byte = Encoding.ASCII.GetBytes(htmlHeader)

        ' Send HTML Header back to Web Browser
        clientSocket.Send(headerByte, 0, headerByte.Length, SocketFlags.None)

        ' Send HTML Content back to Web Browser
        clientSocket.Send(strBuff, 0, len, SocketFlags.None)

    End Sub

    ' Get Content Type
    Private Function getContentType(ByVal httpRequest As String) As String
        If (httpRequest.EndsWith("html")) Then
            Return "text/html"
        ElseIf (httpRequest.EndsWith("htm")) Then
            Return "text/html"
        ElseIf (httpRequest.EndsWith("txt")) Then
            Return "text/plain"
        ElseIf (httpRequest.EndsWith("gif")) Then
            Return "image/gif"
        ElseIf (httpRequest.EndsWith("jpg")) Then
            Return "image/jpeg"
        ElseIf (httpRequest.EndsWith("jpeg")) Then
            Return "image/jpeg"
        ElseIf (httpRequest.EndsWith("pdf")) Then
            Return "application/pdf"
        ElseIf (httpRequest.EndsWith("pdf")) Then
            Return "application/pdf"
        ElseIf (httpRequest.EndsWith("doc")) Then
            Return "application/msword"
        ElseIf (httpRequest.EndsWith("xls")) Then
            Return "application/vnd.ms-excel"
        ElseIf (httpRequest.EndsWith("ppt")) Then
            Return "application/vnd.ms-powerpoint"
        Else
            Return "text/plain"
        End If
    End Function
End Class

端模块

Answer 1

    Dim t As Thread
    t = New Thread(AddressOf server.serve)
    t.Start()