Processing RSS Feeds with Namespaces in Android

Question

I'm trying to write an XML parser that takes an RSS feed & fetches the image urls shown in the url attribute of the <media:thumbnail> tag. This is all being done via android.Util.Xml, & is an adaptation of the code shown here. An example RSS feed that I'm trying to use is the BBC News RSS feed.

However, media is an additional namespace & (probably) as a result my parser isn't working as it should.

A version of my parse method is below. Is there any (no doubt simple) way to get my list of image URLs working?

public List<string> parse() {
    URL feedUrl = new URL("http://newsrss.bbc.co.uk/rss/newsonline_uk_edition/front_page/rss.xml");

    InputStream feedStream;

    try {
        feedStream = feedUrl.openConnection().getInputStream();
    } catch (IOException e) {
        throw new RuntimeException(e);
    }              

    final List<string> ret = new ArrayList<string>();

    RootElement root = new RootElement("rss");
    Element channel = root.getChild("channel");
    Element item = channel.getChild("item");

    item.getChild("media", "thumbnail").getChild("url").setEndTextElementListener(new EndTextElementListener() {
        public void end(String body) {
            ret.add(body);
        }
    });

    try {
        Xml.parse(feedStream, Xml.Encoding.UTF_8, root.getContentHandler());
    } catch (Exception e) {
        throw new RuntimeException(e);
    }

    return ret;
}

Answer 1

In as far as I can tell the "android" SAX parser has no support for namespace (xmlns) nesting (despite the rootelement object specifically mentioning namespace), the stripped "J2SE" SAX parser is also crippled in the way, and the DOM parser is weighty, but operational.

I use DOM with XML namespaces with success, but would prefer a SAX solution that did not involve adding a working XML library like JDOM to my packages.

Answer 2

One way I found that the Xml parser (on Froyo 2.2) works with namespace prefixes is by specifying the namespace URL as the first parameter to your item.getChild() call. For example, if your xml looks like this, you code can use the xmlns url as the first parameter.

<?xml version="1.0" encoding="utf-8"?><rss xmlns:atom="http://www.w3.org/2005/Atom" xmlns:sample="http://www.example_web_site_here.com/dtds/sample_schema.dtd" version="2.0">
    <channel><item><sample:duration>1:00:00</sample:duration></item></channel></rss>

Your listener setup would look like this to get the duration element text:

 item.getChild("http://www.example_web_site_here.com/dtds/sample_schema.dtd", "duration").setEndTextElementListener(new EndTextElementListener(){
            public void end(String body) {
                this.itemDuration = body;
            } });

It requires knowledge of the namespace, but it has been working for me. In my case, I know the name space.