I have the following code that extracts urls from a given page using jsoup.
import org.jsoup.Jsoup;
import org.jsoup.helper.Validate;
import org.jsoup.nodes.Document;
import org.jsoup.nodes.Element;
import org.jsoup.select.Elements;
import java.io.IOException;
/**
* Example program to list links from a URL.
*/
public class ListLinks {
public static void main(String[] args) throws IOException {
String url = "http://shopping.yahoo.com";
print("Fetching %s...", url);
Document doc = Jsoup.connect(url).get();
Elements links = doc.getElementsByTag("a");
print("\nLinks: (%d)", links.size());
for (Element link : links) {
print(" * a: <%s> (%s)", link.absUrl("href") /*link.attr("href")*/, trim(link.text(), 35));
}
}
private static void print(String msg, Object... args) {
System.out.println(String.format(msg, args));
}
private static String trim(String s, int width) {
if (s.length() > width)
return s.substring(0, width-1) + ".";
else
return s;
}
}
What I'm trying to do, is to build a crawler that extracts only https
site. I give the crawler a seed link to start with, then it should extracts all https
site, then take each of the extracted link and do the same with them until reaching a certain number of collected urls.
My questions: The above code can extract all links in a given page. I need to extract links that starts with https://
only, what do I need to do in order to achieve this ?
You can use selectors of jsoup
. They are pretty powerful.
doc.select("a[href*=https]");//(This is the one you are looking for)selects if value of href contatins https
doc.select("a[href^=www]");//selects if value of href starts with www
doc.select("a[href$=.com]");//selects if value of href ends with .com.
etc.. Experiment with them, you will find out the correct one.
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