Getting current Node Value with XPath in Java

Question

I'm building an application in Java and I have some problems with getting some values

The idea is that I have an XML document in the cloud (in this case Last.fm API), and I want to retrieve a value of a node, wich have an attribute. This value is a string, and I want to get it using the attribute

An example for Last.Fm XML is the following:

<track>
  <id>1019817</id>
  <name>Believe</name>
  <mbid/>
  <url>http://www.last.fm/music/Cher/_/Believe</url>
  <duration>240000</duration>
  <streamable fulltrack="1">1</streamable>
  <listeners>69572</listeners>
  <playcount>281445</playcount>
  <artist>
    <name>Cher</name>
    <mbid>bfcc6d75-a6a5-4bc6-8282-47aec8531818</mbid>
    <url>http://www.last.fm/music/Cher</url>
  </artist>
  <album position="1">
    <artist>Cher</artist>
    <title>Believe</title>
    <mbid>61bf0388-b8a9-48f4-81d1-7eb02706dfb0</mbid>
    <url>http://www.last.fm/music/Cher/Believe</url>
    <image size="small">http://userserve-ak.last.fm/serve/34/8674593.jpg</image>
    <image size="medium">http://userserve-ak.last.fm/serve/64/8674593.jpg</image>
    <image size="large">http://userserve-ak.last.fm/serve/126/8674593.jpg</image>
  </album>
  <toptags>
    <tag>
      <name>pop</name>
      <url>http://www.last.fm/tag/pop</url>
    </tag>
    ...
  </toptags>
  <wiki>
    <published>Sun, 27 Jul 2008 15:44:58 +0000</published>
    <summary>...</summary>
    <content>...</content>
  </wiki>
</track>

So my idea is to get for example the image value with the attribute "medium"

I've done the following code using XMLPath:

DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = factory.newDocumentBuilder();
Document documento = builder.parse("http://ws.audioscrobbler.com/2.0/?method=track.getInfo&api_key=" + apikey + "&artist=cher&track=believe");
XPathFactory xPathfactory = XPathFactory.newInstance();
XPath xpath = xPathfactory.newXPath();
XPathExpression expr = xpath.compile("//lfm/track/album/image[@size='medium']");
NodeList nlLastFm = (NodeList) expr.evaluate(documento, XPathConstants.NODESET);
Element eLastFm = (Element) nlLastFm.item(0);
Log.i(TAG, "eLastFm: " + nlLastFm.item(0));
coverUrl = parser.getValue(eLastFm, "image");

But the problem is that it doesn't return correctly the value. I searched a lot of other posts related but they didn't solve my problem...

Could anybody help me?

Thanks for your help!

Answer 1

Try:

String value = nlLastFm.item(0).getTextContent()

A little test code(with smaller piece of your xml and xpath edited accordingly)

public static void main(String[] args) throws ParserConfigurationException,
            SAXException, IOException, XPathExpressionException {
        String xml = "<album position=\"1\"><artist>Cher</artist><title>Believe</title><mbid>61bf0388-b8a9-48f4-81d1-7eb02706dfb0</mbid><url>http://www.last.fm/music/Cher/Believe</url><image size=\"small\">http://userserve-ak.last.fm/serve/34/8674593.jpg</image><image size=\"medium\">http://userserve-ak.last.fm/serve/64/8674593.jpg</image><image size=\"large\">http://userserve-ak.last.fm/serve/126/8674593.jpg</image></album>";

        InputStream stream = new ByteArrayInputStream(xml.getBytes("UTF-8"));

        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        DocumentBuilder builder = factory.newDocumentBuilder();
        Document documento = builder.parse(stream);
        XPathFactory xPathfactory = XPathFactory.newInstance();
        XPath xpath = xPathfactory.newXPath();
        XPathExpression expr = xpath.compile("//album/image[@size='medium']");
        NodeList nlLastFm = (NodeList) expr.evaluate(documento,
                XPathConstants.NODESET);

        String coverUrl = nlLastFm.item(0).getTextContent();
        System.out.println(coverUrl);

    }

Outputs http://userserve-ak.last.fm/serve/64/8674593.jpg