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Parsing an updating html using jsoup [closed]

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we have a problem (we are a group).
We have to use jsoup in java for an university project. We can parse Htmls with it. But the problem is that we have to parse an html which updates when you click on a button (https://www.bundestag.de/services/opendata).
First Slide
Second Slide
We want to access all xmls from "Wahlperiode 20". But when you click on the slide buttons the html code updates but the html url stays the same. But you have never access to all xmls in the html because the html is updating over the slide button.
Another idea was to find out how the urls of the xmls we want to access are built so that we dont have to deal with the slide buttons and only access the xml urls. But they are all built different.
So we are all desperate how to go on. I hope y'all can help us :)

It's rather ironic that you are attempting to hack1 out some data from an opendata website. There is surely an API!!
The problem is that websites aren't static resources; they have javascript, and that javascript can fetch more data in response to e.g. the user clicking a 'next page' button.
What you're doing is called 'scraping': Using automated tools to attempt to query for data via a communication channel (namely: This website) which is definitely not meant for that. This website is not meant to be read with software. It's meant to be read with eyeballs. If someone decides to change the design of this page and you did have a working scraper, it would then fail after the design update, for example.
You have, in broad strokes, 3 options:
Abort this plan, this is crazy
This data is surely open, and open data tends to come with APIs; things meant to be queried by software and not by eyeballs. Go look for it, and call the german government, I'm sure they'll help you out! If they've really embraced the REST principles of design, then send an accept header that including e.g. application/json and application/xml and does not include text/html and see if the site just responds with the data in JSON or XML format.
I strongly advise you fully exhaust these options before moving on to your next options, as the next options are really bad: Lots of work and the code will be extremely fragile (any updates on the site by the bundestag website folks will break it).
Use your browser's network inspection tools
In just about every browser there's 'dev tools'. For example, in Vivaldi, it's under the "Tools" menu and is called "Developer tools". You can also usually right click anywhere on a web page and there will be an option for 'Inspect', 'Inspector', or 'Development Tools'. Open that now, and find the 'network' tab. When you (re)load this page, you'll see all the resources its loading in (so, images, the HTML itself, CSS, the works). Look through it, find the interesting stuff. In this specific case, the loading of wahlperioden.json is of particular interest.
Let's try this out:
curl 'https://www.bundestag.de/static/appdata/filter/wahlperioden.json'
[{"value":"20","label":"WP 20: seit 2021"},{"value":"19","label":"WP 19: 2017 - 2021"},(rest omitted - there are a lot of these)]
That sounds useful, and as its JSON you can just read this stuff with a json parser. No need to use JSoup (JSoup is great as a library, but it's a library that you can use when all other options have failed, and any code written with JSoup is fragile and complicated simply because scraping sites is fragile and complicated).
Then, click on the buttons that 'load new data' and check if network traffic ensues. And so it does, when you do so, you notice a call going out. And so it is! I'm seeing this URL being loaded:
https://www.bundestag.de/ajax/filterlist/de/services/opendata/866354-866354?limit=10&noFilterSet=true&offset=10
The format is rather obvious. offset=10 means: Start from the 10th element (as I just clicked 'next page') and limit=10 means: NO more than 10 pages.
This html is also incredibly basic which is great news, as that makes it easy to scrape. Just write a for loop that keeps calling this URL, modifying the offset=10 part (first loop: no offset. Second, offset=10, third: offset=20. Keep going until the HTML you get back is blank, then you got it all).
For future reference: Browser emulation
Javascript can also generate entire HTML on its own; not something jsoup can ever do for you: The only way to obtain such HTML is to actually let the javascript do its work, which means you need an entire browser. Tools like selenium will start a real browser but let you use JSoup-like constructs to retrieve information from the page (instead of what browsers usually do, which is to transmit the rendered data to your eyeballs). This tends to always work, but is incredibly complicated and quite slow (you're running an entire browser and really rendering the site, even if you can't see it - that's happening under the hood!).
Selenium isn't meant as a scraping tool; it's meant as a front-end testing tool. But you can use it to scrape stuff, and will have to if its generated HTML. Fortunately, you're lucky here.
Option 1 is vastly superior to option 2, and option 2 is vastly superior to option 3, at least for this case. Good luck!
[1] I'm using the definition of: Using a tool or site to accomplish something it was obviously not designed for. The sense of 'I bought half an ikea cupboard and half of an ikea bookshelf that are completely unrelated, and put them together anyway, look at how awesome this thingie is' - that sense of 'hack'. Not the sense of 'illegal'.

How do I send a query to a website and parse the results?

I want to do some development in Java. I'd like to be able to access a website, say for example
www.chipotle.com
On the top right, they have a place where you can enter in your zip code and it will give you all of the nearest locations. The program will just have an empty box for user input for their zip code, and it will query the actual chipotle server to retrieve the nearest locations. How do I do that, and also how is the data I receive stored?
This will probably be a followup question as to what methods I should use to parse the data.
Thanks!

First you need to know the parameters needed to execute the query and the URL which these parameters should be submitted to (the action attribute of the form). With that, your application will have to do an HTTP request to the URL, with your own parameters (possibly only the zip code). Finally parse the answer.
This can be done with standard Java API classes, but it won't be very robust. A better solution would be HttpClient. Here are some examples.

This will probably be a followup question as to what methods I should use to parse the data.
It very much depends on what the website actually returns.
If it returns static HTML, use an regular (strict) or permissive HTML parser should be used.
If it returns dynamic HTML (i.e. HTML with embedded Javascript) you may need to use something that evaluates the Javascript as part of the content extraction process.
There may also be a web API designed for programs (like yours) to use. Such an API would typically return the results as XML or JSON so that you don't have to scrape the results out of an HTML document.
Before you go any further you should check the Terms of Service for the site. Do they say anything about what you are proposing to do?
A lot of sites DO NOT WANT people to scrape their content or provide wrappers for their services. For instance, if they get income from ads shown on their site, what you are proposing to do could result in a diversion of visitors to their site and a resulting loss of potential or actual income.
If you don't respect a website's ToS, you could be on the receiving end of lawyers letters ... or worse. In addition, they could already be using technical means to make life difficult for people to scrape their service.

Extract All Images From HTML Using JAVA

I want to get the list of all Image urls from HTML source of a webpage(Both abosulte and relative urls). I used Jsoup to parse the HTML but its not giving all images. For example when I am parsing google.com HTML source its showing zero images..In google.com HTML source image links are in form..
"background:url(/intl/en_com/images/srpr/logo1w.png)
And in rediff.com the images links are in form..
videoArr[j]=new Array("http://ishare.rediff.com/video/entertainment/bappi-da-the-first-indian-in-grammy-jury/2684982","http://datastore.rediff.com/h86-w116/thumb/5E5669666658606D6A6B6272/v3np2zgbla4vdccf.D.0.bappi.jpg","Bappi Da - the first Indian In Grammy jury","http://mypage.rediff.com/profile/getprofile/LehrenTV/12669275","LehrenTV","(2:33)");
j = 1
videoArr[j]=new Array("http://ishare.rediff.com/video/entertainment/bebo-shahid-jab-they-met-again-/2681664","http://datastore.rediff.com/h86-w116/thumb/5E5669666658606D6A6B6272/ra8p9eeig8zy5qvd.D.0.They-Met-Again.jpg","Bebo-Shahid : Jab they met again!","http://mypage.rediff.com/profile/getprofile/LehrenTV/12669275","LehrenTV","(2:17)");
All images are not with in "img" tags..I also want to extract images which are not even with in "img" tags as shown in above HTML source.
How can I do this..?Please help me on this..
Thanks

This is going to be a bit difficult, I think. You basically need a library that will download a web page, construct the page's DOM and execute any javascript that may alter the DOM. After all that is done you have to extract all the possible images from the DOM. Another possible option is to intercept all calls by library to download resources, examine the URL and if the URL is an image record that URL.
My suggestion would be to start by playing with HtmlUnit(http://htmlunit.sourceforge.net/gettingStarted.html.) It does a good job of building the DOM. I'm not sure what types of hooks it has, for intercepting the methods that download resources. Of course if it doesn't provide you with the hooks you can always use AspectJ or simply modify the HtmlUnit source code. Good luck, this sounds like a reasonably interesting problem. You should post your solution, when you figure it out.

If you just want every image referred to in the page, can't you just scan the HTML and any linked javascript or CSS with a simple regex? How likely is it you'd get [-:_./%a-zA-Z0-9]*(.jpg|.png|.gif) in the HTML/JS/CSS that's not an image? I'd guess not very likely. And you should be allowing for broken links anyway.
Karthik's suggestion would be more correct, but I imagine it's more important to you to just get absolutely everything and filter out uninteresting images.

Get the content of the HTTP stream in Java + Mozilla XPCOM

I've often read StackOverflow as a source to get answers; but now I have a very specific question and I can't really find any data on the internet. I trust you to be as helpful as always! :D
Basically, I'm relying on Mozilla's XULRunner and its XPCOM objects to analyze the HTTP stream of an SWT browser in a Java application on Linux.
Heavily based on Snippet128 and Snippet321 from the Java SWT website (can't post more than 1 URL sorry :/ ), my browser so far can parse all of the HTTP headers using an nsIHttpHeaderVisitor - and do some pretty stuff like printing them on a tree and such.
Full source is here.
Now... That's already pretty good. It covers the majority of what I want to do (school assignment at first, going a bit further than asked!).
But what I would really like is to be able to get the raw "content" data from every HTTP request: HTML of course ; but also CSS and images.
I've been trying different ways to achieve this goal, but everything failed so far:
Using an XPCOM object - which one?
nsIInputStream would be a good one. But I can't seem to find where the good stream actually is... The nsIHttpChannel open() method (who gives back an nsIInputStream) seems to be called by the SWT browser, leaving me with no way of getting the stream back.
nsIRequest : no luck.
another Listener that I'd have missed? I just spent an hour trying to use the nsIHttpActivityObserver interface, but it doesn't give me any HTTP content (merely GETs and 200 OK).
Using another object
the SWT's browser for instance. Well it kinda works: its getText() method gives me the html source of the page I'm visiting. But I want more!
I'm really stuck here, and I would greatly appreciate any help.
Cheers!
Florent

Perhaps nsITraceableChannel can help you?

Is there a validating HTML parser implemented in Java?

I need to parse HTML 4 in Java.
Ideally I'd like an implementation that is SAX compatible.
I'm aware that there are numerous HTML parsers in for Java, however, they all seem to perform 'tidying'. In other words, they will correct badly formed HTML. I don't want this.
My requirements are:
No tidying.
If the input document is invalid HTML parsing should fail.
The document should be validatable against the HTML DTDs.
The parser can produce SAX2 events.
Is there a library that meets these requirements?

You can find a collection of HTML parsers here HTML Parsers. I don't remeber exactly but I think TagSoup parses the file without applying corrections...

I think the Jericho HTML Parser can deliver at least one of your core requirements ('If the input document is invalid HTML parsing should fail.') in that it will at least tell you if there are mismatched tags or other poisonous HTML flaws, and you can choose to fail based on this information.
Try typing invalid html into this Jericho formatting demo, and note the 'Parser Log' at the bottom of the page:
http://jerichohtmlparser.appspot.com/samples/FormatSource.jsp
So yes, this is doing tag tidying, but it is at least telling you about it - you can grab this information by setting a net.htmlparser.jericho.Logger (e.g. a WriterLogger or something more specific of your own creation) on your source, and then proceeding depending on what errors are logged out. This is a small example:
Source source=new Source("<a>I forgot to close my link!");
source.setLogger(myListeningLogger);
source.getSourceFormatter().writeTo(new NullWriter());
// myListeningLogger has now had all the HTML flaws written to it
In the example above, your logger's info() method is called with the string: 'StartTag at (r1,c1,p0) missing required end tag', which is relatively parseable, and you can always decide to just reject any HTML that logs any message worse than debug - in fact Jericho logs almost all errors as 'info' level, with a couple at 'warn' level (you might be tempted to create a small fork with the severities adjusted to correspond to what you care about).
Jericho is available on Maven Central, which is always a good sign:
http://mvnrepository.com/artifact/net.htmlparser.jericho/jericho-html
Good luck!

You may wish to check http://lobobrowser.org/cobra.jsp. They have a pure Java web browser (Lobo) implemented. They have the parser component (Cobra) pulled out separately for use. I honestly am not sure if it will do what you require with the "no tidying" requirement, but it may be worth a look. I ran across it when exploring the wild for a pure Java web browser.

You can try to subclass javax.swing.text.html.parser.Parser and implement the handleXXX() methods. It seems it doesn't try to fix the XML. See more at the API