Using java to extract a single value from an html page:

Question

I am continuing work on a project that I've been at for some time now, and I have been struggling to pull some data from a website. The website has an iframe that pulls in some data from an unknown source. The data is in the iframe in a tag something like this:

<DIV id="number_forecast"><LABEL id="lblDay">9,000</LABEL></DIV>

There is a BUNCH of other crap above it but this div id / label is totally unique and is not used anywhere else in the code.

Answer 1

jsoup is probably what you want, it excels at extracting data from an HTML document.

There are many examples available showing how to use the API: http://jsoup.org/cookbook/extracting-data/selector-syntax

The process will be in two steps:

• parse the page and find the url of the iframe
• parse the content of the iframe and extract the information you need

The code would look like this:

 // let's find the iframe
 Document document = Jsoup.parse(inputstream, "iso-8859-1", url);
 Elements elements = document.select("iframe");
 Element iframe = elements.first();

 // now load the iframe
 URL iframeUrl = new URL(iframe.absUrl("src"));
 document = Jsoup.parse(iframeUrl, 15000);

 // extract the div
 Element div = document.getElementById("number_forecast");