B4J Question webview - return if host reachable?

[bogdanc]

Hi All!

How to return that host is reachable.
I'm loading a web page by webview.
How to return info that page is reachable or not.
Same as You have functionality in any web browser.

Thank You!

 

[Erel]

Add a state listener:

Private Sub AddStateListener(wv As WebView)
   Dim jo As JavaObject = wv
   Dim event As Object = jo.CreateEventFromUI("javafx.beans.value.ChangeListener", "statechanged", Null)
   jo.RunMethodJO("getEngine", Null).RunMethodJO("getLoadWorker", Null).RunMethodJO("stateProperty", Null) _
     .RunMethod("addListener", Array(event))
End Sub

Private Sub statechanged_Event (MethodName As String, Args() As Object) As Object
   Dim newState As String = Args(2)
   Log($"New state: ${newState}"$)
   If newState = "FAILED" Then
     fx.Msgbox(MainForm, "Error loading page", "")   
   End If
   Return Null
End Sub

 

[bogdanc]

Add a state listener:

Private Sub AddStateListener(wv As WebView)
   Dim jo As JavaObject = wv
   Dim event As Object = jo.CreateEventFromUI("javafx.beans.value.ChangeListener", "statechanged", Null)
   jo.RunMethodJO("getEngine", Null).RunMethodJO("getLoadWorker", Null).RunMethodJO("stateProperty", Null) _
     .RunMethod("addListener", Array(event))
End Sub

Private Sub statechanged_Event (MethodName As String, Args() As Object) As Object
   Dim newState As String = Args(2)
   Log($"New state: ${newState}"$)
   If newState = "FAILED" Then
     fx.Msgbox(MainForm, "Error loading page", "")  
   End If
   Return Null
End Sub

Hi Erel!

Thank You for replay!!!


This working perfect.

I observed something. When I use some random domain name it's responding very quick but when I use an IP like: 192.168.1.5 it;s takes around minute to get response.


Below my sample code with Yours listener.

Sub Process_Globals
    Private fx As JFX
    Private MainForm As Form
    Private WebView1 As WebView
       
    Dim joWV As JavaObject
   
End Sub

Sub AppStart (Form1 As Form, Args() As String)
    MainForm = Form1
    MainForm.SetFormStyle("UNIFIED")
    MainForm.RootPane.LoadLayout("webview_test") 'Load the layout file.
   
        WebView1.Enabled=True
        Dim url As String
        url="http://192.168.1.5"
        WebView1.LoadUrl(url)
        AddStateListener(WebView1)
    MainForm.Show
End Sub

Private Sub AddStateListener(wv As WebView)
   Dim jo As JavaObject = wv
   Dim event As Object = jo.CreateEventFromUI("javafx.beans.value.ChangeListener", "statechanged", Null)
   jo.RunMethodJO("getEngine", Null).RunMethodJO("getLoadWorker", Null).RunMethodJO("stateProperty", Null) _
     .RunMethod("addListener", Array(event))
End Sub

Private Sub statechanged_Event (MethodName As String, Args() As Object) As Object
   Dim newState As String = Args(2)
   Log($"New state: ${newState}"$)
   If newState = "FAILED" Then
'     fx.Msgbox(MainForm, "Error loading page", "")  
    Log( "Error loading page")  
   End If
   Return Null
End Sub

 

[bogdanc]

Another question.

How to remove listener from the event above?

 

[Erel]

Why do you need to remove it?

 

[bogdanc]

Why do you need to remove it?

I'm connecting to web page for getting data.
I need to remove listener if I disconnected from the page and start listening again if I will press connect

 

[Erel]

What happens if you keep the listener?

 

[bogdanc]

• I'm loading some web page to webview
• on that page i have some data (I refreshing webview every 1s to refresh the data, I used a timer for that)
• when I finish my readings I need to disconnect.
• I enabling timer in the listener and I cannot disconnect because listener keep the timer on

 

[Erel]

Why can't you disable the timer? Use a global variable to know when you should ignore the state changed events.