使用jsoup登录网站

Question

On this website , you can enter your student-card-number, and then it will display how much money is left on that card. I want to obtain the information using JSOUP. This is my current code, but it does not work,

        String url = "http://kortladdning3.chalmerskonferens.se/CardLoad_Order.aspx";



        Connection.Response loginForm = Jsoup.connect(url)
                .method(Connection.Method.GET)
                .execute();

        Document document = Jsoup.connect(url)
                .userAgent("Mozilla/5.0 (Macintosh; Intel Mac OS X 10_10_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/44.0.2403.157 Safari/537.36")               
                 //.data("__VIEWSTATE","%2FwEPDwUHNjA4NDA1NQ9kFgQCAw9kFgoCAQ9kFgICAQ8PFgIeBFRleHQFClBUTSBLb3J0bnJkZAICDxYCHgdWaXNpYmxlaGQCAw8WAh8BaGQCBA8WAh8BaGQCBQ8WAh8BaBYCAgEPEGRkFgBkAgUPDxYCHwAFCShkZXNrdG9wKWRkZGzBhwMIv3yxqKnC0C7%2BPlC0PlDG")
                .data("__EVENTVALIDATION", "%2FwEWBAKG7bXPBQLi0uqnCgKF69rWBAK14fOOCgrUt4CBVP4K0VKe0uOPxLSAu26y")
                .data("hiddenIsMobile", "desktop")
                .data("txtCardNumber", "3819276248xxxxxx")
                .data("SavedCardNumber", "")
                .data("btnNext","N%C3%A4sta")
                .cookies(loginForm.cookies())
                .get();


        System.out.println(document.html());

I dont have much experience so I dont know where to look for the problem. Some thoughts:

• Should I use .post() or .get() ?
• When looking in chrome devoloper tools, the post data is all the data I send with .data(.., ..) function. However if a send __VIEWSTATE I get an error, why?
• Should I send decrypted or crypted data? (both are presented in chrome devoloper tools).
• Am using the correct URL?

Answer 1

You should use both get and post :
First you have to send get request with no parameters to the URL - http://kortladdning3.chalmerskonferens.se/Default.aspx . The server replies with some cookies, and two values you'll use later - __VIEWSTATE and __EVENTVALIDATION . These values vary from request to request, so you can't use hard-coded values like you did.
After extracting these values, send post request, with the same fields you do now.
You can look at a very similar procedure here - Problems submitting a login form with Jsoup