用Socket类构建网页下载器

Private Sub btnHTML_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnHTML.Click
　　Dim serverIP As IPAddress = Dns.Resolve("http://www.Tuenhai.com").AddressList(0)
　　' Default Web Server Port = 80
　　Dim Port As String = "80"
　　Dim serverhost As New IPEndPoint(serverIP, Int32.Parse(Port))

　　Dim clientSocket As New Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp)

　　Try
　　　　clientSocket.Connect(serverhost)

　　　　If clientSocket.Connected = False Then
　　　　　　MsgBox("Connect Error.", MsgBoxStyle.Critical, "HTTP")
　　　　　　Exit Sub
　　　　End If

　　　　Dim httpReq As String = "GET / HTTP/1.0" & ControlChars.CrLf & ControlChars.CrLf

　　　　clientSocket.Send(ASCII.GetBytes(httpReq))

　　　　Dim buffer(1024) As Byte
　　　　Dim byteCount As Int16 = clientSocket.Receive(buffer, buffer.Length, 0)

　　　　txtHTML.Text = ASCII.GetString(buffer, 0, byteCount)

　　　　Do While byteCount > 0
　　　　　　byteCount = clientSocket.Receive(buffer, buffer.Length, 0)
　　　　　　txtHTML.Text = txtHTML.Text & ASCII.GetString(buffer, 0, byteCount)
　　　　Loop
　　Catch ex As Exception
　　 　MsgBox(ex.StackTrace.ToString(), MsgBoxStyle.Critical, "Exception")
　　End Try
End Sub