Android Open Source - TinyRss Reader

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License

The source code is released under:

Copyright (c) 2012, Tiny Mission LLC All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met...

Java Source Code

package com.tinymission.rss;
/*from  w  w  w  .j  a  va2s  . c  om*/
import android.util.Log;
import org.xml.sax.Attributes;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.XMLReader;
import org.xml.sax.helpers.DefaultHandler;

import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
import java.util.Stack;

/**
 * Reads an RSS feed and creates and RssFeed object.
 */
public class Reader {

  private URL _url;
  
  /** The allowed tags to parse content from (everything else gets lumped into its parent content, which allows for embedding html content.
   * 
   */
  public final static String[] CONTENT_TAGS = {"title", "link", "description", "language", "pubDate", "lastBuildDate", "docs", "generator", "managingEditor", "webMaster", "guid", "author", "category"};
  
  /** The tags that should be parsed into separate entities, not just properties of existing entities.
   * 
   */
  public final static String[] ENTITY_TAGS = {"channel", "item", "media:content", "media:thumbnail"};

  /**
   * @return whether tag is a valid content tag
   */
  public static boolean isContentTag(String tag) {
    for (String t: CONTENT_TAGS) {
      if (t.equalsIgnoreCase(tag)) {
        return true;
      }
    }
    return false;
  }

  /**
   * @return whether tag is a valid entity tag
   */
  public static boolean isEntityTag(String tag) {
    for (String t: ENTITY_TAGS) {
      if (t.equals(tag)) {
        return true;
      }
    }
    return false;
  }

  /**
   * @param url The URL of the feed.
   */
  public Reader(URL url) {
    _url = url;
  }
  
  /**
   * Assumes the URL is valid and will throw a runtime excpetion if not.
   * Use the constructor taking a URL value as the argument if you aren't sure if you have a valid url.
   * @param url The URL of the feed.
   */
  public Reader(String url) {
    try {
      _url = new URL(url);
    }
    catch (MalformedURLException mue) {
      throw new RuntimeException("Bad URL for RSS feed reader");
    }
  }

  /** Actually grabs the feed from the URL and parses it into java objects.
   * 
   * @return The feed object containing all the feed data.
   */
  public Feed fetchFeed() {
    Feed feed = null;

    try {
      SAXParserFactory spf = SAXParserFactory.newInstance();
      SAXParser sp = spf.newSAXParser();

      XMLReader xr = sp.getXMLReader();

      Handler handler = new Handler();
      xr.setContentHandler(handler);
      
      URLConnection ucon = _url.openConnection();
      InputStream is = ucon.getInputStream();
      xr.parse(new InputSource(is));
      is.close();

      feed = handler.getFeed();

    } catch (ParserConfigurationException pce) {
      Log.e("SAX XML", "sax parse error", pce);
    } catch (SAXException se) {
      Log.e("SAX XML", "sax error", se);
    } catch (IOException ioe) {
      Log.e("SAX XML", "sax parse io error", ioe);
    }
    return feed;
  }
  
  
  /** SAX handler for parsing RSS feeds.
   *
   */
  public class Handler extends DefaultHandler {

    // Keep track of which entity we're currently assigning properties to
    private Stack<FeedEntity> _entityStack;
    
    public Handler() {
      _feed = new Feed();
      _entityStack = new Stack<FeedEntity>();
      _entityStack.add(_feed);
    }

    private Feed _feed;
    
    private StringBuilder _contentBuilder;
    
    public Feed getFeed() {
      return _feed;
    }

    @Override
    public void startDocument() throws SAXException {
      _contentBuilder = new StringBuilder();
    }

    @Override
    public void endDocument() throws SAXException {
      // TODO Auto-generated method stub
      super.endDocument();
    }

    @Override
    public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
      if (isContentTag(localName)) {
        _contentBuilder = new StringBuilder();
      }
      else if (isEntityTag(qName)) {
        if (qName.equals("item")) {
          Item item = new Item(attributes);
          _entityStack.add(item);
          _feed.addItem(item);
        }
        else if (qName.equals("media:content")) {
          MediaContent mediaContent = new MediaContent(attributes);
          FeedEntity lastEntity = _entityStack.lastElement();
          if (lastEntity.getClass() == Item.class) {
            ((Item)lastEntity).setMediaContent(mediaContent);
          }
          _entityStack.add(mediaContent);
        } 
        else if (qName.equals("media:thumbnail")) {
          MediaThumbnail mediaThumbnail = new MediaThumbnail(attributes);
          FeedEntity lastEntity = _entityStack.lastElement();
          if (lastEntity.getClass() == Item.class) {
            Item item = (Item)lastEntity;
            MediaThumbnail existingMt = item.getMediaThumbnail();
            if (existingMt == null) {
              item.setMediaThumbnail(mediaThumbnail);
            }
          }
          _entityStack.add(mediaThumbnail);
        } 
        else if (qName.equals("channel")) {
          // this is just the start of the feed
        }
        else {
          throw new RuntimeException("Don't know how to create an entity from tag " + qName);
        }
      }
    }

    @Override
    public void endElement(String uri, String localName, String qName) throws SAXException {
      // get the latest parsed content, if there is any
      String content = "";
      if (isContentTag(qName)) {
        content = _contentBuilder.toString().trim();
        
        _entityStack.lastElement().setProperty(localName, content);
      }
      else if (isEntityTag(qName)) {
        _entityStack.pop();
      }
    }

    @Override
    public void characters(char[] ch, int start, int length)
        throws SAXException {
      
      String content = new String(ch, start, length); 
      _contentBuilder.append(content); 
    }
    
    
    
  }

}

Java Source Code List

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