examples/rss/src/main/java/org/apache/commons/digester3/rss/RSSDigester.java

package org.apache.commons.digester3.rss;

/*
 * 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.
 */

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

import org.apache.commons.digester3.Digester;
import org.apache.commons.logging.LogFactory;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;


/**
 * <p>Implementation of <strong>org.apache.commons.digester3.Digester</strong>
 * 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</a> site.</p>
 *
 * <p>The default implementation object returned by calling
 * <code>parse()</code> (an instance of
 * <code>org.apache.commons.digester3.rss.Channel</code>)
 * knows how to render itself in XML format via the <code>render()</code>
 * method.  See the test <code>main()</code> 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;

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

    /**
     * The fully qualified class name of the <code>Channel</code>
     * implementation class.
     */
    protected String channelClass = "org.apache.commons.digester3.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</code>
     * implementation class.
     */
    protected String imageClass = "org.apache.commons.digester3.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</code>
     * implementation class.
     */
    protected String itemClass = "org.apache.commons.digester3.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</code>
     * implementation class.
     */
    protected String textInputClass = "org.apache.commons.digester3.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
     *
     * @throws IOException if an input/output error occurs
     * @throws SAXException if a parsing exception occurs
     */
    @Override
    public <T> T parse( File file )
        throws IOException, SAXException
    {
        configure();
        return ( super.<T>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
     *
     * @throws IOException if an input/output error occurs
     * @throws SAXException if a parsing exception occurs
     */
    @Override
    public <T> T parse( InputSource input )
        throws IOException, SAXException
    {
        configure();
        return ( super.<T>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
     *
     * @throws IOException if an input/output error occurs
     * @throws SAXException if a parsing exception occurs
     */
    @Override
    public <T> T parse( InputStream input )
        throws IOException, SAXException
    {
        configure();
        return ( super.<T>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
     *
     * @throws IOException if an input/output error occurs
     * @throws SAXException if a parsing exception occurs
     */
    @Override
    public <T> T parse( String uri )
        throws IOException, SAXException
    {
        configure();
        return ( super.<T>parse( uri ) );
    }

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

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

    /**
     * Configure the parsing rules that will be used to process RSS input.
     */
    @Override
    protected void configure()
    {
        if ( configured )
        {
            return;
        }

        // 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.digester3.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.digester3.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.digester3.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/digester3/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 );
        }
    }

}