Parsing XML attributes with DOM

From:
Ian Wilson <scobloke2@infotop.co.uk>
Newsgroups:
comp.lang.java.help
Date:
Mon, 06 Nov 2006 17:06:06 +0000
Message-ID:
<JJWdnZoMZKwf9tLYRVnyjA@bt.com>
I am trying to extract attributes of elements and failing.
In the example below I want to extract the value("Kg") of the "units"
attribute of the element weight.

My code is based on "XML Cookbook" by Ian F Darwin, OReilly.
21.4 Parsing XML with DOM.

-------------------- animals.xml ------------------------
<inventory>
   <animal type="mammal">
     <name>Fred</name>
     <species>Hippo</species>
     <weight units="Kg">1552</weight>
   </animal>
   <animal type="reptile">
     <name>Gert</name>
     <species>Croc</species>
   </animal>
</inventory>
-------------------- ParseXML.java -----------------------
import java.io.File;
import java.io.IOException;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;

import org.w3c.dom.Document;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;

public class ParseXML {

     public static void main(String[] args) {

         String filename = "XML/animals.xml";

         String uri = "file:" + new File(filename).getAbsolutePath();
         Document doc = null;
         try {
             DocumentBuilderFactory factory = DocumentBuilderFactory
                     .newInstance();
             DocumentBuilder builder = factory.newDocumentBuilder();
             doc = builder.parse(uri);
         } catch (ParserConfigurationException e) {
             e.printStackTrace();
         } catch (SAXException e) {
             e.printStackTrace();
         } catch (IOException e) {
             e.printStackTrace();
         }
         doRecursive(doc, "");
     } // main

     private static void doRecursive(Node node, String name) {
         if (node == null)
             return;
         NodeList nodes = node.getChildNodes();
         for (int i = 0; i < nodes.getLength(); i++) {
             Node n = nodes.item(i);
             if (n == null)
                 continue;
             doNode(n, name);
         }
     }

     private static void doNode(Node node, String name) {
         String nodeName = "unknown";
         switch (node.getNodeType()) {
         case Node.ELEMENT_NODE:
             if (name.length() == 0) {
                 nodeName = node.getNodeName();
             } else {
                 nodeName = name + "." + node.getNodeName();
             }
             doRecursive(node, nodeName);
             break;
         case Node.TEXT_NODE:
             String text = node.getNodeValue();
             if (text.length() == 0 || text.matches("\n *")
                     || text.equals("\\r")) {
                 break;
             }

             // I seem to be on the wrong track here!
             String type = "";
             NamedNodeMap attrs = node.getAttributes();
             if (attrs != null) {
                 Node attr = attrs.getNamedItem("type");
                 if (attr != null) {
                     type = attr.getNodeValue();
                 }
             }

             System.out.println(name + "(" + type + ") = '"
                                     + text + "'.");
             nodeName = "unknown";
             break;
         default:
             System.out.println("Other node " + node.getNodeType()
                     + " : " + node.getClass());
             break;
         }
     } // doNode()

}
------------------------------ actual output ------------------
inventory.animal.name() = 'Fred'.
inventory.animal.species() = 'Hippo'.
inventory.animal.weight() = '1552'.
inventory.animal.name() = 'Gert'.
inventory.animal.species() = 'Croc'.
-------------------------------- desired output ---------------
inventory.animal.name() = 'Fred'.
inventory.animal.species() = 'Hippo'.
inventory.animal.weight(Kg) = '1552'.
inventory.animal.name() = 'Gert'.
inventory.animal.species() = 'Croc'.
---------------------------------------------------------------

Clues?

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