/* Copyright 2002-2004 Elliotte Rusty Harold
This library is free software; you can redistribute it and/or modify
it under the terms of version 2.1 of the GNU Lesser General Public
License as published by the Free Software Foundation.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the
Free Software Foundation, Inc., 59 Temple Place, Suite 330,
Boston, MA 02111-1307 USA
You can contact Elliotte Rusty Harold by sending e-mail to
[email protected]. Please include the word "XOM" in the
subject line. The XOM home page is located at http://www.xom.nu/
*/
package nu.xom.samples;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Set;
import nu.xom.Attribute;
import nu.xom.Builder;
import nu.xom.Document;
import nu.xom.Element;
import nu.xom.Elements;
/**
*
* <p>
* Demonstrates the reading of attributes in namespaces,
* as well as maintaining a stack of hierarchy-based state
* during document traversal.
* </p>
*
* @author Elliotte Rusty Harold
* @version 1.0
*
*/
public class XLinkSpider {
private Set spidered = new HashSet();
private Builder parser = new Builder();
private List queue = new LinkedList();
public static final String XLINK_NS
= "http://www.w3.org/1999/xlink";
public static final String XML_NS
= "http://www.w3.org/XML/1998/namespace";
public void search(URL url) {
try {
String systemID = url.toExternalForm();
Document doc = parser.build(systemID);
System.out.println(url);
search(doc.getRootElement(), url);
}
catch (Exception ex) {
// just skip this document
}
if (queue.isEmpty()) return;
URL discovered = (URL) queue.remove(0);
spidered.add(discovered);
search(discovered);
}
private void search(Element element, URL base) {
Attribute href = element.getAttribute("href", XLINK_NS);
Attribute xmlbase = element.getAttribute("base", XML_NS);
try {
if (xmlbase != null) {
base = new URL(base, xmlbase.getValue());
}
}
catch (MalformedURLException ex) {
// Probably just no protocol handler for the
// kind of URLs used inside this element
return;
}
if (href != null) {
String uri = href.getValue();
// absolutize URL
try {
URL discovered = new URL(base, uri);
// remove fragment identifier if any
discovered = new URL(
discovered.getProtocol(),
discovered.getHost(),
discovered.getFile()
);
if (!spidered.contains(discovered)
&& !queue.contains(discovered)) {
queue.add(discovered);
}
}
catch (MalformedURLException ex) {
// skip this one
}
}
Elements children = element.getChildElements();
for (int i = 0; i < children.size(); i++) {
search(children.get(i), base);
}
}
public static void main(String[] args) {
XLinkSpider spider = new XLinkSpider();
for (int i = 0; i < args.length; i++) {
try {
spider.search(new URL(args[i]));
}
catch (MalformedURLException ex) {
System.err.println(ex);
}
}
} // end main()
}
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