Visual Basic Improvements in Visual Studio 11: Listing 1.
Loading the four Web pages with synchronous Get method.
Const msdnURL = "http://www.msdn.com"
Const bingURL = "http://www.bing.com"
Private Sub btnLoadPagesSync_Click(sender As Object, e As EventArgs) Handles btnLoadPagesSync.Click
'No Web pages will appear until they are all loaded
Call DoLoadPagesSync()
End Sub
Private Sub DoLoadPagesSync()
'Load each page synchronously over http for demo
btnLoadPagesSync.BackColor = Color.Red
Application.DoEvents()
Dim StartTime = Now
UpdateWebControlSync(msdnURL, wb1)
UpdateWebControlSync(bingURL, wb2)
UpdateWebControlSync(msdnURL, wb3)
UpdateWebControlSync(bingURL, wb4)
btnLoadPagesSync.BackColor = System.Windows.Forms.Button.DefaultBackColor
lblElapsedSynch.Text = "Button response Time: " & DateTime.Now.Subtract(StartTime).ToString
End Sub
Private Sub UpdateWebControlSync(webPageURL As String, wc As WebBrowser)
'Simple method to display Web pages on a windows form
Try
wc.DocumentText = ""
'Using synchonous Get method rather than asynchronous GetAsync method
'Synchronous call to retrieve the HTML, method is not suspended during load
Dim response = New System.Net.Http.HttpClient().Get(New System.Uri(webPageURL))
'Sync method as completed and execution continues
Dim pageHTML = response.Content.ReadAsString
wc.Document.Write(pageHTML)
Catch ex As Exception
Dim msg = "Exception: {0}" & vbCrLf & vbCrLf & "{1}"
MessageBox.Show(String.Format(msg, ex.Message, ex.InnerException.Message))
End Try
Return
End Sub
About the Author
Joe Kunk is a Microsoft MVP in Visual Basic, three-time president of the Greater Lansing User Group for .NET, and developer for Dart Container Corporation of Mason, Michigan. He's been developing software for over 30 years and has worked in the education, government, financial and manufacturing industries. Kunk's co-authored the book "Professional DevExpress ASP.NET Controls" (Wrox Programmer to Programmer, 2009). He can be reached via email at [email protected].