Reading/Parsing RSS feed using ROME

ROME is an open source tool to parse, generate and publish RSS and Atom feeds. Using Rome you can parse the available RSS and Atom feeds. Without bothering about format and version of RSS feed. The core library depends on the JDOM XML parser.
Atom is on the similar lines of RSS is another kind of feed. But it’s different in some aspects as protocol, payloads.
RSS is a method to share and publish contents. The contents may be any things from news to any little information. The main component is xml. Using xml you can share your contents on web. At the same time you are free to get what you like from others.

Why use Rome instead of other available readers

The Rome project started with the motivation of ‘ESCAPE’ where each letter stands for:
E – Easy to use. Just give a URL and forget about its type and version, you will be given a output in the format which you like.
S – Simple. Simple structure. The complications are all hidden from developers.
C – Complete. It handles all the versions of RSS and Atom feeds.
A – Abstract. It provides abstraction over various syndication specifications.
P – Powerful. Don’t worry about the format let Rome handle it.
E – Extensible. It needs a simple pluggable architecture to provide future extension of formats.

Dependency

Following are few dependencies:
J2SE 1.4+, JDOM 1.0, Jar files (rome-0.8.jar, purl-org-content-0.3.jar, jdom.jar)

Using Rome to read a Syndication Feed

Considering you have all the required jar files we will start with reading the RSS feed. ROME represents syndication feeds (RSS and Atom) as instances of the com.sun.syndication.synd.SyndFeed interface.
ROME includes parsers to process syndication feeds into SyndFeed instances. The SyndFeedInput class handles the parsers using the correct one based on the syndication feed being processed. The developer does not need to worry about selecting the right parser for a syndication feed, the SyndFeedInput will take care of it by peeking at the syndication feed structure. All it takes to read a syndication feed using ROME are the following 2 lines of code:

SyndFeedInput input = new SyndFeedInput();
SyndFeed feed = input.build (new XmlReader (feedUrl));

Now it’s simple to get the details of Feed. You have the object.

The sample code is as follows.

import java.net.URL;
import java.util.Iterator;
 
import com.sun.syndication.feed.synd.SyndEntry;
import com.sun.syndication.feed.synd.SyndFeed;
import com.sun.syndication.io.SyndFeedInput;
import com.sun.syndication.io.XmlReader;
 
/**
 * @author Hanumant Shikhare
 */
public class Reader {
 
  public static void main(String[] args) throws Exception {
 
    URL url  = new URL("http://viralpatel.net/blogs/feed");
    XmlReader reader = null;
 
    try {
 
      reader = new XmlReader(url);
      SyndFeed feed = new SyndFeedInput().build(reader);
      System.out.println("Feed Title: "+ feed.getAuthor());
 
     for (Iterator i = feed.getEntries().iterator(); i.hasNext();) {
        SyndEntry entry = (SyndEntry) i.next();
        System.out.println(entry.getTitle());
            }
        } finally {
            if (reader != null)
                reader.close();
        }
    }
}

Understanding the Program

Initialize the URL object with the RSS Feed or Atom url. Then we will need XMLReader object which will then take URL object, as its constructor argument. Initialize the SyndFeed object by calling the build(reader) method. This method takes the XMLReader object as an argument.

References

https://rome.dev.java.net/
http://www.intertwingly.net/wiki/pie/Rss20AndAtom10Compared
http://www.rss-specifications.com