How can I detect that there is an internet connection?

Question

How can I detect that there is an internet connection?
Peter Goossens

Answer 1

How can I detect that there is an internet connection?
Peter Goossens
Peter,
You might want to experiment with this. It's not perfect, but...
Class
Imports System.IO
Imports System.Net
Namespace InternetConnection
Public Class SiteInfo
Private _displayName As String
Private _connectionString As String
Private Sub New(ByVal name As String, _
ByVal connectionString As String)
_displayName = name.Trim
_connectionString = connectionString.Trim
End Sub
''' <summary>
''' Gets the connection string of this instance.
''' </summary>
''' <value></value>
''' <returns></returns>
''' <remarks></remarks>
Public ReadOnly Property ConnectionString() As String
Get
Return _connectionString
End Get
End Property
''' <summary>
''' Gets the display name of this instance.
''' </summary>
''' <value></value>
''' <returns></returns>
''' <remarks></remarks>
Public ReadOnly Property DisplayName() As String
Get
Return _displayName
End Get
End Property
''' <summary>
''' A method which will add a new site to your collection of SiteInfo.
''' </summary>
''' <param name="siList">Your generic List(Of SiteInfo).</param>
''' <param name="displayName">The display name for this new instance
''' of SiteInfo.</param>
''' <param name="connectionString">The connection string for this
''' new instance of SiteInfo.</param>
''' <remarks></remarks>
Public Shared Sub AddNew(ByRef siList As List(Of SiteInfo), _
ByVal displayName As String, _
ByVal connectionString As String)
Try
If siList Is Nothing Then
Throw New NullReferenceException("The collection of SiteInfo cannot be null.")
ElseIf String.IsNullOrEmpty(displayName) OrElse displayName.Trim = "" Then
Throw New ArgumentException("The display name cannot be null or empty.")
ElseIf String.IsNullOrEmpty(connectionString) OrElse connectionString.Trim = "" Then
Throw New ArgumentException("The connection string cannot be null or empty.")
Else
If siList.Count > 0 Then
Dim findDuplicate As IEnumerable(Of SiteInfo) = _
From si As SiteInfo In siList _
Where si.DisplayName.ToLower.Replace(" "c, "") = _
displayName.ToLower.Replace(" "c, "") AndAlso _
si.ConnectionString.ToLower.Replace(" "c, "") = _
connectionString.ToLower.Replace(" "c, "")
If findDuplicate.Count <> 0 Then
Throw New ArgumentException("This is a duplicate entry.")
Else
siList.Add(New SiteInfo(displayName, connectionString))
End If
Else
siList.Add(New SiteInfo(displayName, connectionString))
End If
End If
Catch ex As Exception
Throw
End Try
End Sub
''' <summary>
''' A method which will return a boolean value to indicate internet
''' connection status.
''' </summary>
''' <param name="siList">Your generic List(Of SiteInfo).</param>
''' <param name="displayName">The display name for the instance
''' of SiteInfo to use.</param>
''' <returns></returns>
''' <remarks></remarks>
Public Shared Function InternetIsConnected(ByVal siList As List(Of SiteInfo), _
ByVal displayName As String) As Boolean
Dim retVal As Boolean = False
Try
If siList Is Nothing Then
Throw New NullReferenceException("The collection of SiteInfo cannot be null.")
ElseIf siList.Count = 0 Then
Throw New ArgumentOutOfRangeException("Count", "The collection of SiteInfo cannot be empty.")
ElseIf String.IsNullOrEmpty(displayName) OrElse displayName.Trim = "" Then
Throw New ArgumentException("The display name cannot be null or empty.")
Else
Dim findInstance As IEnumerable(Of SiteInfo) = _
From si As SiteInfo In siList _
Where si.DisplayName.ToLower.Replace(" "c, "") = _
displayName.ToLower.Replace(" "c, "")
If findInstance.Count <> 1 Then
Throw New ArgumentException("This instance is not in the collection of SiteInfo.")
Else
retVal = TestConnection(findInstance.First.ConnectionString)
End If
End If
Catch ex As Exception
Throw
End Try
Return retVal
End Function
Private Shared Function TestConnection(ByVal url As String) As Boolean
Dim retVal As Boolean = False
Try
Dim request As WebRequest = WebRequest.Create(url)
Using response As HttpWebResponse = DirectCast(request.GetResponse, HttpWebResponse)
Using dataStream As Stream = response.GetResponseStream
Using reader As New StreamReader(dataStream)
Dim responseFromServer As String = reader.ReadToEnd()
retVal = True
End Using
End Using
End Using
Catch ex As WebException
retVal = True
Catch ex As Exception
retVal = False
End Try
Return retVal
End Function
End Class
End Namespace
Example Usage
Public Class Form1
Private Sub Form1_Load(ByVal sender As System.Object, _
ByVal e As System.EventArgs) _
Handles MyBase.Load
Dim siList As New List(Of InternetConnection.SiteInfo)
InternetConnection.SiteInfo.AddNew(siList, _
"Test1", _
"http://dev.virtualearth.net/REST/v1/Locations/37221?o=xml")
InternetConnection.SiteInfo.AddNew(siList, _
"Test2", _
"nothing here")
InternetConnection.SiteInfo.AddNew(siList, "Test3", _
"www.google.com")
InternetConnection.SiteInfo.AddNew(siList, "Test4", _
"http://fls-online.com")
' This will return true:
Dim bool1 As Boolean = _
InternetConnection.SiteInfo.InternetIsConnected(siList, _
"Test1")
' This will return false:
Dim bool2 As Boolean = _
InternetConnection.SiteInfo.InternetIsConnected(siList, _
"Test2")
' This will return false:
Dim bool3 As Boolean = _
InternetConnection.SiteInfo.InternetIsConnected(siList, _
"Test3")
' This will return true:
Dim bool4 As Boolean = _
InternetConnection.SiteInfo.InternetIsConnected(siList, _
"Test4")
Stop
End Sub
End Class
Let me know your results please?
Still lost in code, just at a little higher level.