XML newbie - parsing RSS

Question

Hello Everbody,
i started playing around with xml and i am finding it very interesting...i have a question, how does one transform an rss feed using Java.(to use on my home page for example)? I know that they have an RSSUtilities package here on java.sun.com but i wanted to try it out on my own so that i get more experience using it..
i was successfully able to parse xml docs using sax and dom approaches..(i use jaxp by the way..) also, i can transform xml to html using dom and xslt stylesheets but feeds?? if i use the same program that i used for sml files, at run time i get the following errors..
Error: URI=file:D:/javapractice/inrss.xml Line=2: Element type "rss" is n
ot declared.
Error: URI=file:D:/javapractice/inrss.xml Line=2: Attribute "version" is
not declared for element "rss".
Error: URI=file:D:/javapractice/inrss.xml Line=3: Element type "channel"
is not declared.
Error: URI=file:D:/javapractice/inrss.xml Line=4: Element type "title" is
not declared.
Error: URI=file:D:/javapractice/inrss.xml Line=5: Element type "link" is
not declared.
Error: URI=file:D:/javapractice/inrss.xml Line=6: Element type "descripti
on" is not declared.
Error: URI=file:D://javapractice/inrss.xml Line=7: Element type "language"
is not declared.
Error: URI=file:D://javapractice/inrss.xml Line=8: Element type "pubDate"
is not declared.
Error: URI=file:D://javapractice/inrss.xml Line=9: Element type "copyright
" is not declared.
Error: URI=file:D://javapractice/inrss.xml Line=10: Element type "image" i
s not declared.
i think the above is understood because there is no dtd for these rss feeds... please, help me understand this as i am going crazy with this problem

Answer 1

Hi Nachida,
The code is very simple and I am posting it as below.. Please note that if I use a regular xml file, it gives me correct results but if I use an RSS feed, it complains..
First the code..
import org.xml.sax.helpers.DefaultHandler;
import java.io.File;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import org.w3c.dom.Document;
import org.w3c.dom.DOMException;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.TransformerConfigurationException;
import javax.xml.transform.TransformerException;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import javax.xml.transform.stream.StreamSource;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;
import javax.xml.parsers.ParserConfigurationException;
import java.io.IOException;
public class TransformRss
{ Document document;
     public TransformRss()
          {try
               {DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
                 dbFactory.setValidating(true);
                dbFactory.setIgnoringElementContentWhitespace(true);
                DocumentBuilder documentBuilder = dbFactory.newDocumentBuilder();
                document = documentBuilder.parse(new File("inrss.xml"));
          catch (SAXException e)
          {System.out.println("This is a SAX Exception");
          catch (ParserConfigurationException e)
          {System.out.println("This is a Parser Configuration Exception");
          catch (IOException e)
          {System.out.println("This is a IO Exception");
     public void transformTheDocument(File stylesheet)
          {try
               {Transformer transformer = TransformerFactory.newInstance().newTransformer(new                 StreamSource(stylesheet));
                transformer.transform(new DOMSource(document), new StreamResult( new File("alteredRss.html")));
          catch (TransformerConfigurationException e)
               {System.out.println("This a transformer configuration exception");
          catch (TransformerException e)
               {System.out.println(" this is a transformer exception");
     public static void main(String[] args) throws Exception
          {TransformRss transformRss = new TransformRss();
           transformRss.transformTheDocument(new File("program.xsl"));
Now instead of rss.xml if I want to transform lets say resumexml.xml it works fine... I am posting both resumexml.xml and inrss.xml
resumexml.xml-----------------------------------------------------------------------------------------
<?xml version="1.0"?>
<!DOCTYPE resume [
<!ELEMENT resume (name, education, country)>
<!ELEMENT name (#PCDATA)>
<!ELEMENT education (#PCDATA)>
<!ELEMENT country (#PCDATA)>
]>
<resume>
<name>sabrang</name>
<education> engineer </education>
<country> usa </country>
</resume>
inrss.xml--------------------------------------// or it could be any rss type of file...
<?xml version="1.0" ?>
<rss version="0.91">
<channel>
<title>rediff Top Stories - India</title>
<link>http://www.rediff.com/</link>
<description>India's largest news and entertainment service online.</description>
<language>en-us</language>
<pubDate>Sat, 10 Apr 2004 19:44:36 GMT</pubDate>
<copyright>Copyright: (C) 2004 Rediff.com India Limited. All Rights Reserved.</copyright>
<image>
<title>rediff.com</title>
<url>http://www.rediff.com/uim/red_log.gif</url>
<link>http://www.rediff.com/</link>
<width>144</width>
<height>28</height>
<description>Visit rediff.com</description>
</image>
<item>
<title>I am a Bihari by birth, saysVajpayee</title>
<link>http://www.rediff.com/rss/redirect.php?url=http://www.rediff.com/election/2004/apr/10pm.htm</link>
<description>'I am a Bihari by birth. I was named Bihari by my father the day I was born,' the prime minister said in Patna.</description>
</item>
<item>
<title>US army asks for ceasefire in Fallujah</title>
<link>http://www.rediff.com/rss/redirect.php?url=http://www.rediff.com/news/2004/apr/10iraq.htm</link>
<description>After more than a week of fighting the US army has occupied only a small portion of the town.</description>
</item>
<item>
<title>'We'd like to have a Shoaib in our side' </title>
<link>http://www.rediff.com/rss/redirect.php?url=http://www.rediff.com/cricket/2004/apr/10inter.htm</link>
<description>India coach John Wright analyses the tour of Pakistan and discusses his future with the Indian team.</description>
</item>
<item>
<title>Vaghela vs Vaghela in Kapadvanj</title>
<link>http://www.rediff.com/rss/redirect.php?url=http://www.rediff.com/election/2004/apr/10guj1.htm</link>
<description>Of the seven assembly segments in the constituency, four are with the BJP and the rest with the Congress. So, whichever way you look at it, it is going to be a contest of equals.</description>
</item>
<item>
<title>Paes/Bhupathi give India 2-1 lead</title>
<link>http://www.rediff.com/rss/redirect.php?url=http://www.rediff.com/sports/2004/apr/10doubles.htm</link>
<description>The ace doubles pair beat Thomas Shimada and Takahiro Terachi in the doubles rubber of the Davis Cup Asia/Oceania Group I tie.</description>
</item>
<item>
<title>On the road to peace, a dream bloodied</title>
<link>http://www.rediff.com/rss/redirect.php?url=http://www.rediff.com/news/2004/apr/10uri.htm</link>
<description>Just a few days back the prospects of the Srinagar-Muzzafarabad road reopening had looked bright.</description>
</item>
</channel>
</rss>