How to detect if the computer is connected to the net using VB.NET (Windows Form)? How to bring up how can bring up the dial-up window so that the user can dial to the net? (FAQ from the newsgroup)
Introduction:
In the article we'll see how to check connectivity with internet using VB.NET and if its not connected give the client the flexibility to get connected.
Snippet:
To check if there is connection establish to internet we'll write function which returns a boolean value. (true if connected, false if not). We'll need to use the Namespace System.Net.
Dim webreq As HttpWebRequest
Dim webresp As HttpWebResponse
'Funtion returns tru or false base on the HttpStatusCode
Function checkconnection(ByVal url As String) As Boolean
Dim strurl As String = url
Dim bConnected As Boolean = False
Try
webreq = WebRequest.Create(strurl)
webresp = webreq.GetResponse
If webresp.StatusCode = HttpStatusCode.OK Then
bConnected = True
Else
bConnected = False
End If
Return bConnected
Catch ex As Exception
bConnected = False
Return bConnected
Finally
webresp = Nothing
End Try
End Function
As a part of user interface lets have a Textbox (where the user can enter the URL) and Button control. On click of the button we'll check if the client is connected to internet.
If not connected we'll bring up the "Network and Dial-Up Connections" (Here we'll use Shell command)
If connected we'll open the browser window with the URL specified by the client.(We'll use Process class of System.Diagnostics namespace).Here goes the code to be written on button click.
Dim lNg As Integer
Dim urlString As String = TextBox1.Text
Dim isConnected As Boolean = checkconnection(urlString)
If isConnected Then
System.Diagnostics.Process.Start("iexplore", urlString)
Else
Dim ans As String = MsgBox("Do you want to connect?", MsgBoxStyle.YesNo, "No Connected")
If ans = vbYes Then
lNg = Shell("rundll32.exe shell32.dll,Control_RunDLL ncpa.cpl,,0")
Else
MsgBox("Sorry canot connect you chose no...")
End If
End If