Android Question Get HTTP redirect page

Shay · Sep 16, 2017

I am going to some URL, and this page is redirecting to another page
I need to get the new page after it is redirected
I need to get the response and not actually display it
how do I do it with okHTTP?

OliverA · Sep 16, 2017

okHttp automatically handles redirects.

Example: going to "https://jigsaw.w3.org/HTTP/300/302.html" will end up at "https://jigsaw.w3.org/HTTP/300/Overview.html"

Below code was tested in B4J 5.9 with only the jCore (Version 5.8) and jOkHttpUtils2_NONUI (version 2.62) libraries checked.

B4X:

'Non-UI application (console / server application)
#Region Project Attributes
    #CommandLineArgs:
    #MergeLibraries: True
#End Region

Sub Process_Globals
   
End Sub

Sub AppStart (Args() As String)
    doit
    StartMessageLoop
End Sub

Sub doit
    Dim job As HttpJob
    job.Initialize("", Me)
    job.Download("https://jigsaw.w3.org/HTTP/300/302.html")

    Wait For (job) jobDone(job As HttpJob)
    If job.Success Then
        Log(job.GetString)
    Else
        Log($"Error: ${job.ErrorMessage}"$)
    End If
    job.Release

    StopMessageLoop
End Sub

'Return true to allow the default exceptions handler to handle the uncaught exception.
Sub Application_Error (Error As Exception, StackTrace As String) As Boolean
    Return True
End Sub

Shay · Sep 16, 2017

I tried it (without the Start and StopMessageLoop - cannot find it on B4A)
and it still gives first page data

OliverA · Sep 16, 2017

Ok, tried it in B4A (7.30) using both the OkHttpUtils2 (Version 2.61) and HttpUtils2 (Version 2.50) libraries, and automatic redirection worked. If you manually add the class code/module code of these libraries and modified them, you may need to look at your modifications and see if it changed something in regards to redirects (turned it off?)

B4X:

' Process_Globals and Regions above this
'
Sub Globals
    Dim Panel1 As Panel
End Sub

Sub Activity_Create(FirstTime As Boolean)
    Panel1.Initialize("")
    Panel1.Visible=True
    Activity.AddView(Panel1, 0, 0, 100%x, 100%y)

    doit
   
End Sub

Sub doit
    Dim job As HttpJob
    job.Initialize("", Me)
    job.Download("https://jigsaw.w3.org/HTTP/300/302.html")

    Wait For (job) jobDone(job As HttpJob)
    If job.Success Then
        Log(job.GetString)
    Else
        Log($"Error: ${job.ErrorMessage}"$)
    End If
    job.Release

End Sub
'Activity_Resume and Activity_Pause below this

Output:

*** Service (starter) Create ***
** Service (starter) Start **
** Activity (main) Create, isFirst = true **
** Activity (main) Resume **
*** Service (httputils2service) Create ***
** Service (httputils2service) Start **
<!DOCTYPE html>
<html>
<head>
<title>Redirect test page</title>
</head>
<body bgcolor="white">
<p><a href=".."><img src="/icons/jigsaw" alt="Jigsaw" border="0"
width="212" height="49"></a><img src="/icons/jigpower.gif" width=
"94" height="52" alt="Jigsaw Powered !" border="0" align=
"right"></p>
<h1>Redirect test page</h1>
<h1>A set of HTTP/1.1 redirect codes</h1>
<hr>
<table border cellpadding="2">
<tr>
<td><a href="301.html">301 Moved Permanently</a></td>
<td>This links to a page that has moved permanently, your browser
should get back to this page after this link.</td>
</tr>
<tr>
<td><a href="302.html">302 Found</a></td>
<td>This links to a page that has moved permanently, your browser
should get back to this page after this link.<br>
<em>302 Found</em> is ambiguous, you may use 301 or 307
instead</td>
</tr>
<tr>
<td>
<form action="Go_303" method="post"><input type="hidden" name="foo"
value="bar"> <input type="submit" value="303 See Other"></form>
</td>
<td>This form will redirect you to another page that contains the
response to the request.</td>
</tr>
<tr>
<td><a href="307.html">307 Moved Temporarily</a></td>
<td>This links to a page that has moved temporarily, your browser
should get back to this page after this link. This response code is
not cachable, unless specified.</td>
</tr>
<tr>
<td>
<form action="Go_307" method="post"><input type="hidden" name="foo"
value="bar"> <input type="submit" value=
"Redirect to the 303 test"></form></td>
<td>This form will redirect a POST using 307 to the 303 test page.
If the UA redirect as a GET, an error will occur.</td>
response to the request.</td>
</tr>
</table>
</body>
</html>

Shay · Sep 20, 2017

still not working to me, I assume it is either related to some java script or the redirect happens after 1-2 seconds and not right away
you can see it on Jewish Saturday or holiday such as today
http://www.holyclock.com
if you enter the site (click english) on Sat or Holiday it will redirect you to other page, which it seems I cannot get it

OliverA · Sep 20, 2017

So are you trying to get the page that shows that the site is closed (example: http://www.holyclock.com/closed?do=demo) or are you trying to get to the originating page (http://www.holyclock.com/)?

Shay · Sep 20, 2017

exactly
on Israel, it is now redirecting to the "closed site" reason: "Rosh Hashana"
it is redirecting now to:
http://www.holyclock.com/closed?dat...2d10c24+1+59c53c4e++http://www.holyclock.com/

OliverA · Sep 20, 2017

So are you trying to get to the actual site instead of the re-directed site? So instead of following the re-direction (which okhttp does), your trying to "un-redirect" it?

Shay · Sep 20, 2017

no, I am trying to get the closed page, but I am getting the actual site (twice)

OliverA · Sep 20, 2017

I'll check it out when I get a chance (if I don't want to change a clock, I'll have to wait a little bit).

OliverA · Sep 20, 2017

Maybe the site is doing a refresh instead of redirect and okhttp or whatever underlying library does not forward the site due to it being a refresh (just guessing).

See the accepted answer to this stackoverflow question: https://stackoverflow.com/questions/11299006/header-location-delay

Edit: If you can print all the headers out from the request, you may get a clue. Look for redirect/refresh

OliverA · Sep 21, 2017

It looks like that particular site used JavaScript's window.location property to redirect the page to the new location. I'm pretty sure the underlying http library used does not understand JavaScript and therefore you are not redirected to the other page.

WARNING: The next suggestion is just from what I've read here and there and has absolutely nothing to do with personal experience with this.

How about using a WebView to load your page. If the WebView processes the JavaScript, should it not properly "redirect" to the next page? Can you then query WebView on what page it is (and, maybe, its contents)? If this happens to work, this could be used even for the "proper" redirects and may even work for "refresh". Please note, I have no clue if it's possible, someone else will have to help out here.

Shay · Sep 21, 2017

Thank you very much for your help, I will give it a try and update

Shay · Sep 21, 2017

just realized, using WebView is problematic, since I am using service

Shay · Sep 21, 2017

b.t.w you are right, this is JS.
I blocked the JS in the browser and it cannot "redirect" the page
now i need to find a way to do it using HTTP request (run JS)

DonManfred · Sep 21, 2017

You can not run Javascript through httputils-calls.

Shay · Sep 21, 2017

so this is dead end?

Shay · Sep 21, 2017

ok, never mind I will write my own DB and use it
Thank you all for your help

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