Commons Digester example source code file (RSSDigester.java)

This example Commons Digester source code file (RSSDigester.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Commons Digester tags/keywords

channel, class, communications//dtd, io, ioexception, ioexception, net, netscape, network, object, object, rss, rssdigester, sax, saxexception, saxexception, string, string

The Commons Digester RSSDigester.java source code

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */ 


package org.apache.commons.digester.rss;


import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;

import org.apache.commons.digester.Digester;
import org.apache.commons.logging.LogFactory;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;


/**
 * <p>Implementation of org.apache.commons.digester.Digester
 * designed to process input streams that conform to the <em>Rich Site
 * Summary</em> DTD, version 0.91.  For more information about this format,
 * see the <a href="http://my.netscape.com/publish/">My Netscape site.

 *
 * <p>The default implementation object returned by calling
 * <code>parse() (an instance of
 * <code>org.apache.commons.digester.rss.Channel)
 * knows how to render itself in XML format via the <code>render()
 * method.  See the test <code>main() method below for an
 * example of using these classes.</p>
 */

public class RSSDigester extends Digester {


    // ----------------------------------------------------------- Constructors



    // ----------------------------------------------------- Instance Variables


    /**
     * Have we been configured yet?
     */
    protected boolean configured = false;


    /**
     * The set of public identifiers, and corresponding resource names,
     * for the versions of the DTDs that we know about.
     */
    protected static final String registrations[] = {
        "-//Netscape Communications//DTD RSS 0.9//EN",
        "/org/apache/commons/digester/rss/rss-0.9.dtd",
        "-//Netscape Communications//DTD RSS 0.91//EN",
        "/org/apache/commons/digester/rss/rss-0.91.dtd",
    };


    // ------------------------------------------------------------- Properties


    /**
     * The fully qualified class name of the <code>Channel
     * implementation class.
     */
    protected String channelClass = "org.apache.commons.digester.rss.Channel";

    public String getChannelClass() {
        return (this.channelClass);
    }

    public void setChannelClass(String channelClass) {
        this.channelClass = channelClass;
    }


    /**
     * The fully qualified class name of the <code>Image
     * implementation class.
     */
    protected String imageClass = "org.apache.commons.digester.rss.Image";

    public String getImageClass() {
        return (this.imageClass);
    }

    public void setImageClass(String imageClass) {
        this.imageClass = imageClass;
    }


    /**
     * The fully qualified class name of the <code>Item
     * implementation class.
     */
    protected String itemClass = "org.apache.commons.digester.rss.Item";

    public String getItemClass() {
        return (this.itemClass);
    }

    public void setItemClass(String itemClass) {
        this.itemClass = itemClass;
    }


    /**
     * The fully qualified class name of the <code>TextInput
     * implementation class.
     */
    protected String textInputClass =
            "org.apache.commons.digester.rss.TextInput";

    public String getTextInputClass() {
        return (this.textInputClass);
    }

    public void setTextInputClass(String textInputClass) {
        this.textInputClass = textInputClass;
    }


    // --------------------------------------------------------- Public Methods


    /**
     * Parse the content of the specified file using this Digester.  Returns
     * the root element from the object stack (which will be the Channel).
     *
     * @param file File containing the XML data to be parsed
     *
     * @exception IOException if an input/output error occurs
     * @exception SAXException if a parsing exception occurs
     */
    public Object parse(File file) throws IOException, SAXException {

        configure();
        return (super.parse(file));

    }


    /**
     * Parse the content of the specified input source using this Digester.
     * Returns the root element from the object stack (which will be the
     * Channel).
     *
     * @param input Input source containing the XML data to be parsed
     *
     * @exception IOException if an input/output error occurs
     * @exception SAXException if a parsing exception occurs
     */
    public Object parse(InputSource input) throws IOException, SAXException {

        configure();
        return (super.parse(input));

    }


    /**
     * Parse the content of the specified input stream using this Digester.
     * Returns the root element from the object stack (which will be
     * the Channel).
     *
     * @param input Input stream containing the XML data to be parsed
     *
     * @exception IOException if an input/output error occurs
     * @exception SAXException if a parsing exception occurs
     */
    public Object parse(InputStream input) throws IOException, SAXException {

        configure();
        return (super.parse(input));

    }


    /**
     * Parse the content of the specified URI using this Digester.
     * Returns the root element from the object stack (which will be
     * the Channel).
     *
     * @param uri URI containing the XML data to be parsed
     *
     * @exception IOException if an input/output error occurs
     * @exception SAXException if a parsing exception occurs
     */
    public Object parse(String uri) throws IOException, SAXException {

        configure();
        return (super.parse(uri));

    }


    // -------------------------------------------------------- Package Methods



    // ------------------------------------------------------ Protected Methods


    /**
     * Configure the parsing rules that will be used to process RSS input.
     */
    protected void configure() {

        if (configured) {
            return;
        }

        // Register local copies of the DTDs we understand
        for (int i = 0; i < registrations.length; i += 2) {
            URL url = this.getClass().getResource(registrations[i + 1]);
            if (url != null) {
                register(registrations[i], url.toString());
            }
        }

        // FIXME - validate the "version" attribute of the rss element?

        // Add the rules for the Channel object
        addObjectCreate("rss/channel", channelClass);
        addCallMethod("rss/channel/copyright", "setCopyright", 0);
        addCallMethod("rss/channel/description", "setDescription", 0);
        addCallMethod("rss/channel/docs", "setDocs", 0);
        addCallMethod("rss/channel/language", "setLanguage", 0);
        addCallMethod("rss/channel/lastBuildDate", "setLastBuildDate", 0);
        addCallMethod("rss/channel/link", "setLink", 0);
        addCallMethod("rss/channel/managingEditor", "setManagingEditor", 0);
        addCallMethod("rss/channel/pubDate", "setPubDate", 0);
        addCallMethod("rss/channel/rating", "setRating", 0);
        addCallMethod("rss/channel/skipDays/day", "addSkipDay", 0);
        addCallMethod("rss/channel/skipHours/hour", "addSkipHour", 0);
        addCallMethod("rss/channel/title", "setTitle", 0);
        addCallMethod("rss/channel/webMaster", "setWebMaster", 0);

        // Add the rules for the Image object
        addObjectCreate("rss/channel/image", imageClass);
        addSetNext("rss/channel/image", "setImage",
                "org.apache.commons.digester.rss.Image");
        addCallMethod("rss/channel/image/description", "setDescription", 0);
        addCallMethod("rss/channel/image/height", "setHeight", 0,
                new Class[]{ Integer.TYPE });
        addCallMethod("rss/channel/image/link", "setLink", 0);
        addCallMethod("rss/channel/image/title", "setTitle", 0);
        addCallMethod("rss/channel/image/url", "setURL", 0);
        addCallMethod("rss/channel/image/width", "setWidth", 0,
                new Class[]{ Integer.TYPE });

        // Add the rules for the Item object
        addObjectCreate("rss/channel/item", itemClass);
        addSetNext("rss/channel/item", "addItem",
                "org.apache.commons.digester.rss.Item");
        addCallMethod("rss/channel/item/description", "setDescription", 0);
        addCallMethod("rss/channel/item/link", "setLink", 0);
        addCallMethod("rss/channel/item/title", "setTitle", 0);

        // Add the rules for the TextInput object
        addObjectCreate("rss/channel/textinput", textInputClass);
        addSetNext("rss/channel/textinput", "setTextInput",
                "org.apache.commons.digester.rss.TextInput");
        addCallMethod("rss/channel/textinput/description",
                "setDescription", 0);
        addCallMethod("rss/channel/textinput/link", "setLink", 0);
        addCallMethod("rss/channel/textinput/name", "setName", 0);
        addCallMethod("rss/channel/textinput/title", "setTitle", 0);

        // Mark this digester as having been configured
        configured = true;

    }


    // ------------------------------------------------------ Test Main Program


    /**
     * Test main program that parses the channel description included in this
     * package as a static resource.
     *
     * @param args The command line arguments (ignored)
     */
    public static void main(String args[]) {

        try {
            System.out.println("RSSDigester Test Program");
            System.out.println("Opening input stream ...");
            InputStream is = RSSDigester.class.getResourceAsStream
                    ("/org/apache/commons/digester/rss/rss-example.xml");
            System.out.println("Creating new digester ...");
            RSSDigester digester = new RSSDigester();
            if ((args.length > 0) && (args[0].equals("-debug"))) {
                digester.setLogger(LogFactory.getLog("RSSDigester"));
            }
            System.out.println("Parsing input stream ...");
            Channel channel = (Channel) digester.parse(is);
            System.out.println("Closing input stream ...");
            is.close();
            System.out.println("Dumping channel info ...");
            channel.render(System.out);
        } catch (Exception e) {
            System.out.println("-->Exception");
            e.printStackTrace(System.out);
        }

    }


}