Java - Retrieving data from a website

https://stackoverflow.com/questions/10059246

29-05-2021
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Domanda

I'm making an application that recovers lottery numbers and displays them in a window. However I've unsure of how I would recover the data and the numbers from the website:

https://www.national-lottery.co.uk/player/p/results.ftl

How would you go about doing this? I have before done this but with a site that returned a String of data which I could use. I'm more unsure of how to do this. Any suggestions would be appreciated and the technique (if there is one) will help me in a lot more of my projects!

Soluzione

The site provides a link to download a CSV version of the numbers. Just use that:

https://www.national-lottery.co.uk/player/lotto/results/downloadResultsCSV.ftl

It looks like:

DrawDate,Ball 1,Ball 2,Ball 3,Ball 4,Ball 5,Ball 6,Bonus Ball,Ball Set,Machine
07-Apr-2012,23,12,42,16,25,31,18,6,LANCELOT
04-Apr-2012,44,23,9,40,33,26,31,2,MERLIN
31-Mar-2012,2,49,40,47,18,5,19,1,MERLIN
28-Mar-2012,16,8,39,22,3,38,26,3,MERLIN
24-Mar-2012,24,27,6,39,31,45,32,4,LANCELOT
21-Mar-2012,10,14,45,25,39,21,40,1,MERLIN
17-Mar-2012,37,40,1,3,20,16,15,2,MERLIN
14-Mar-2012,15,36,26,31,14,18,48,4,MERLIN
10-Mar-2012,12,37,23,43,3,1,33,1,MERLIN
07-Mar-2012,28,44,8,35,11,2,17,3,MERLIN
03-Mar-2012,31,20,40,28,7,23,42,4,MERLIN
29-Feb-2012,41,29,46,14,49,13,43,3,LANCELOT
25-Feb-2012,29,27,26,7,32,25,33,1,LANCELOT
22-Feb-2012,35,12,7,49,43,15,8,4,MERLIN
18-Feb-2012,19,22,30,33,41,2,24,4,LANCELOT
15-Feb-2012,30,40,28,33,9,44,16,3,MERLIN
11-Feb-2012,24,31,23,1,49,45,6,3,LANCELOT
08-Feb-2012,7,13,31,44,36,16,26,8,LANCELOT
04-Feb-2012,41,45,7,40,48,4,46,2,MERLIN
01-Feb-2012,7,39,38,17,22,21,3,2,LANCELOT
28-Jan-2012,10,25,31,40,28,12,1,2,LANCELOT
25-Jan-2012,2,30,8,26,45,39,46,1,MERLIN
21-Jan-2012,17,5,32,39,49,42,19,5,MERLIN
18-Jan-2012,22,43,34,9,31,35,20,6,MERLIN
14-Jan-2012,7,12,10,15,25,42,33,7,LANCELOT
11-Jan-2012,40,33,39,9,2,27,45,6,LANCELOT
07-Jan-2012,47,8,15,17,14,20,38,7,MERLIN
04-Jan-2012,42,43,30,9,28,26,2,8,MERLIN
31-Dec-2011,11,38,42,37,44,7,2,7,LANCELOT
28-Dec-2011,48,11,49,13,17,8,19,6,LANCELOT
24-Dec-2011,43,32,36,15,23,1,19,7,LANCELOT
21-Dec-2011,30,7,28,34,38,45,6,5,MERLIN
17-Dec-2011,42,1,35,48,39,22,12,5,MERLIN
14-Dec-2011,3,43,30,28,10,25,31,8,MERLIN
10-Dec-2011,30,21,29,39,24,16,20,6,LANCELOT
07-Dec-2011,10,31,27,47,32,14,41,5,MERLIN
03-Dec-2011,49,1,35,48,47,30,8,8,MERLIN
30-Nov-2011,30,26,25,24,23,13,4,7,MERLIN
26-Nov-2011,13,36,26,16,25,46,15,6,MERLIN
23-Nov-2011,19,31,48,22,4,11,6,5,MERLIN
19-Nov-2011,32,31,1,34,29,36,45,3,ARTHUR
16-Nov-2011,26,40,39,27,10,12,20,1,GUINEVERE
12-Nov-2011,28,13,12,33,6,38,10,14,ARTHUR
09-Nov-2011,27,2,8,32,23,10,44,1,GUINEVERE
05-Nov-2011,14,24,39,23,16,27,43,8,LANCELOT
02-Nov-2011,12,38,11,33,37,49,3,2,GUINEVERE
29-Oct-2011,49,14,5,28,9,46,45,1,GUINEVERE
26-Oct-2011,4,23,34,41,38,39,27,4,GUINEVERE
22-Oct-2011,20,43,27,44,28,34,1,4,ARTHUR
19-Oct-2011,13,18,34,49,32,14,20,3,GUINEVERE
15-Oct-2011,41,7,12,46,34,27,14,2,ARTHUR
12-Oct-2011,37,26,40,25,13,24,30,3,ARTHUR

Altri suggerimenti

Use Jsoup to retrieve and parse page:

String url = "https://www.national-lottery.co.uk/player/p/results.ftl";
Document document = Jsoup.connect(url).get();
final Elements elementsByTag = document.getElementsByTag("table");
... then work with the table or any other element

Create a URL representation of the page address. Open a connection to the URL. Establish an input stream. Read all of the data from the stream. This will be the page source.

URL url = new URL("https://www.national-lottery.co.uk/player/p/results.ftl");
URLConnection connection = url.openConnection();
InputStream stream = connection.getInputStream();
byte[] data = new byte[stream.available()];

stream.read(data);
stream.close();

String source = new String(data);

Unless the site provides an api or web service that allows querying for lottery numbers, you may have to scrape the html source of the page. It looks like the numbers are stored in a simple html list:

<ul>
  <li>12</li>
  <li>16</li>
  <li>23</li>
  <li>25</li>
  <li>31</li>
  <li>42</li>
  <li class="bonus">18</li>
</ul>

There are lots of good Java HTML parsers out there. Here's a few projects:

I looked around the site you're interested in and it appears they have a "history" page with the lottery numbers over several days:

https://www.national-lottery.co.uk/player/lotto/results/results.ftl

That's probably a better page to scrape from.

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