parse XML and convert to a Collection

Question

<inputs>
  <MAT_NO>123</MAT_NO>
  <MAT_NO>323</MAT_NO>
  <MAT_NO>4223</MAT_NO>
  <FOO_BAR>122</FOO_BAR>
  <FOO_BAR>125</FOO_BAR>
</inputs>

I've to parse the above the XML. After parsing, i want the values to be in a Map<String, List<String>> with Key values corresponding to the child nodes - MAT_NO, FOO_BAR and values - the values of the child nodes -123, 323 etc.

Following is my shot. Is there any better way of doing this??

public class UserInputsXmlParser extends DefaultHandler {

 private final SaveSubscriptionValues subscriptionValues = null;
 private String nodeValue = "";
 private final String inputKey = "";
 private final List<String> valuesList = null;
 private Map<String, List<String>> userInputs;

 public Map<String, List<String>> parse(final String strXML) {
  try {
   final SAXParserFactory parserFactory = SAXParserFactory
     .newInstance();
   final SAXParser saxParser = parserFactory.newSAXParser();
   saxParser.parse(new InputSource(new StringReader(strXML)), this);
   return userInputs;
  } catch (final SAXException e) {
   e.printStackTrace();
   throw new MyException("", e);
  } catch (final IOException e) {
   e.printStackTrace();
   throw new MyException("", e);
  } catch (final ParserConfigurationException e) {
   e.printStackTrace();
   throw new MyException("", e);
  } catch (final Exception e) {
   e.printStackTrace();
   throw new MyException("", e);
  }
 }

 @Override
 public void startElement(final String uri, final String localName,
   final String qName, final Attributes attributes)
   throws SAXException {
  nodeValue = "";

  if ("inputs".equalsIgnoreCase(qName)) {
   userInputs = MyUtil.getNewHashMap();
   return;
  }

 }

 @Override
 public void characters(final char[] ch, final int start, final int length)
   throws SAXException {
  if (!MyUtil.isEmpty(nodeValue)) {
   nodeValue += new String(ch, start, length);
  } else {
   nodeValue = new String(ch, start, length);
  }
 }

 @Override
 public void endElement(final String uri, final String localName,
   final String qName) throws SAXException {
  if (!"inputs".equalsIgnoreCase(qName)) {
   storeUserInputs(qName, nodeValue);
  }

 }

 /**
  * @param qName
  * @param nodeValue2
  */
 private void storeUserInputs(final String qName, final String nodeValue2) {
  if (nodeValue2 == null || nodeValue2.trim().equals("")) { return; }
  final String trimmedValue = nodeValue2.trim();
  final List<String> values = userInputs.get(qName);
  if (values != null) {
   values.add(trimmedValue);
  } else {
   final List<String> valueList = new ArrayList<String>();
   valueList.add(trimmedValue);
   userInputs.put(qName, valueList);
  }
 }

 public static void main(final String[] args) {
  final String sample = "<inputs>" + "<MAT_NO>154400-0000</MAT_NO>"
    + "<MAT_NO>  </MAT_NO>" + "<MAT_NO>154400-0002</MAT_NO>"
    + "<PAT_NO>123</PAT_NO><PAT_NO>1111</PAT_NO></inputs>";
  System.out.println(new UserInputsXmlParser().parse(sample));
 }

}

UPDATE: The children of <inputs> nodes are dynamic. I'll be knowing just the root node.

Answer 1

For something this basic, look into xpath.

Answer 2

Do you have to provide a solution as part of a SAX event handler? If not then you could use one of the many XML libraries around, such as dom4j. Make the solution a lot simpler;

public static void main(String[] args) throws Exception
{
    String sample = "<inputs>" + "<MAT_NO>154400-0000</MAT_NO>"
    + "<MAT_NO>  </MAT_NO>" + "<MAT_NO>154400-0002</MAT_NO>"
    + "<PAT_NO>123</PAT_NO><PAT_NO>1111</PAT_NO></inputs>";

    System.out.println(parse(sample));
}

static Map<String,List<String>> parse(String xml) throws Exception
{
    Map<String,List<String>> map = new HashMap<String,List<String>>();

    SAXReader reader = new SAXReader();
    Document doc = reader.read(new StringReader(xml));

    for (Iterator i = doc.getRootElement().elements().iterator(); i.hasNext();)
    {
        Element element = (Element)i.next();

        //Maybe handle elements with only whitespace text content

        List<String> list = map.get(element.getName());
        if (list == null)
        {
            list = new ArrayList<String>();
            map.put(element.getName(), list);
        }
        list.add(element.getText());
    }

    return map;
}

Answer 3

I would check xstream....( http://xstream.codehaus.org/tutorial.html )