Taming XStream part 3

The final part of this series will detail my attempt to deserialise an arbitary sample XML file into Java objects. I have selected the following RSS feed XML file:

<?xml version="1.0" encoding="UTF-8"?>
<rss version="2.0" xmlns:media="http://search.yahoo.com/mrss/">
    <channel>
        <title>Sample Channel</title> 
        <link>http://www.playstation.com/manual/psp/rss/</link> 
        <description>Contains sample content</description> 
        <language>en-us</language>
        <image>
            <url>http://www.playstation.com/manual/psp/rss/sample_ch.jpg</url>
            <title>Sample Channel</title>
        </image>
        <copyright>&#xA9; 2005 Sony Computer Entertainment Inc. All rights reserved.</copyright>
        <item>
            <title>HOUSE SAMPLE 1</title> 
            <link>http://www.playstation.com/manual/psp/rss/</link> 
            <description>HOUSE SAMPLE 1 / PSP Mix</description>
            <author>Noburo Masuda</author>
            <pubDate>Tue, 29 Nov 2005 15:00:00 +0900</pubDate> 
            <enclosure url="http://fj00.psp.update.playstation.org/media/HOUSE_SAMPLE_1.mp3" type="audio/mp3" /> 
        </item>
        <item>
            <title>JAZZ FUSION SAMPLE 1</title> 
            <link>http://www.playstation.com/manual/psp/rss/</link> 
            <description>JAZZ FUSION SAMPLE 1 / PSP Mix</description>
            <author>Noburo Masuda</author>
            <pubDate>Tue, 29 Nov 2005 14:00:00 +0900</pubDate>
            <enclosure url="http://fj00.psp.update.playstation.org/media/JAZZ_FUSION_SAMPLE_1.mp3" type="audio/mp3" /> 
        </item>
        <item>
            <title>Sample Video Clip</title> 
            <link>http://www.playstation.com/manual/psp/rss/</link> 
            <description>Sample Clip for RSS ch</description>
            <author>Sony Computer Entertainment Inc.</author>
            <pubDate>Thu, 27 Jul 2006 15:00:00 +0900</pubDate>
            <enclosure url="http://fj00.psp.update.playstation.org/media/SampleVideoClip.mp4" type="video/mp4" /> 
    <media:thumbnail url="http://fj00.psp.update.playstation.org/media/SampleVideoClip_tn.jpg" width="60" height="45"/>
        </item>
    </channel>
</rss>

This example includes collections of sub types, attributes and fields. We will need to create a class hierarchy which looks like RSS -> Channel -> Item. Then complete the appropriate field and attribute mapping as required. The following is the structure I have decided on:

private static class RSS {
    private Channel channel;
    public RSS(Channel channel) {
        this.channel = channel;
    }
}

private static class Channel {
    String title;
    String link;
    String description;
    String language;
    Image image;
    String copyright;
    List<Item> items;
}

private static class Image {
    String url;
    String title;
}

private static class Item {
    String title;
    String link;
    String description;
    String author;
    String pubDate;
    Enclosure enclosure;
    Thumbnail thumbnail;
}

private static class Enclosure {
    String url;
    String type;
}

private static class Thumbnail {
    String url;
    int width;
    int height;
}

The following is the completed code listing which correctly deserialises the XML:

package xstream;

import com.thoughtworks.xstream.XStream;
import com.thoughtworks.xstream.io.xml.DomDriver;
import java.util.List;

public class Three {
    public static void main(String [] args) {
        XStream xstream = new XStream(new DomDriver());

        // RSS
        xstream.alias("rss", RSS.class);
        
        // Channel
        xstream.alias("channel", Channel.class);
        xstream.addImplicitCollection(Channel.class, "items", "item", Item.class);

        // Item
        xstream.alias("enclosure", Enclosure.class);
        xstream.alias("media:thumbnail", Thumbnail.class);
        xstream.aliasField("media:thumbnail", Item.class, "thumbnail");
        
        // Enclosure
        xstream.aliasAttribute(Enclosure.class, "type", "type");
        xstream.aliasAttribute(Enclosure.class, "url", "url");

        // Thumbnail
        xstream.aliasAttribute(Thumbnail.class, "url", "url");
        xstream.aliasAttribute(Thumbnail.class, "width", "width");
        xstream.aliasAttribute(Thumbnail.class, "height", "height");
        
        
        RSS data = (RSS) xstream.fromXML(
                One.class.getResourceAsStream("sample_ch.xml"));

        System.out.println(data.toString());
    }

    private static class RSS {
        private Channel channel;
        public RSS(Channel channel) {
            this.channel = channel;
        }

        @Override
        public String toString() {
            return channel.toString();
        }
    }

    private static class Channel {
        String title;
        String link;
        String description;
        String language;
        Image image;
        String copyright;
        List<Item> items;

        @Override
        public String toString() {
            String r = "";
            r += "title: " + title + "\n";
            r += "description: " + description + "\n";
            r += "image: " + image.toString() + "\n";
            r += "copyright: " + copyright + "\n";
            for (Item item : items) {
                r += "\n";
                r += item.toString() + "\n";
            }
            return r;
        }
    }

    private static class Image {
        String url;
        String title;

        @Override
        public String toString() {
            return title + " (" + url + ")";
        }
    }

    private static class Item {
        String title;
        String link;
        String description;
        String author;
        String pubDate;
        Enclosure enclosure;
        Thumbnail thumbnail;

        @Override
        public String toString() {
            String r = "";
            r += "title: " + title + "\n";
            r += "description: " + description + "\n";
            r += "link: " + link + "\n";
            r += "pubDate: " + pubDate + "\n";

            if (enclosure != null) {
                r += enclosure.toString() + "\n";
            }

            if (thumbnail != null) {
                r += thumbnail.toString() + "\n";
            }
            
            return r;
        }
    }

    private static class Enclosure {
        String url;
        String type;

        @Override
        public String toString() {
            return url + " (" + type + ")";
        }
    }

    private static class Thumbnail {
        String url;
        int width;
        int height;

        @Override
        public String toString() {
            return url + " (" + width + "x" + height + ")";
        }
    }
}