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Asked: 2026-05-10T13:45:35+00:00

I’m looking for the best method to parse various XML documents using a Java

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I’m looking for the best method to parse various XML documents using a Java application. I’m currently doing this with SAX and a custom content handler and it works great – zippy and stable.

I’ve decided to explore the option having the same program, that currently recieves a single format XML document, receive two additional XML document formats, with various XML element changes. I was hoping to just swap out the ContentHandler with an appropriate one based on the first ‘startElement’ in the document… but, uh-duh, the ContentHandler is set and then the document is parsed!

... constructor ... { SAXParserFactory spf = SAXParserFactory.newInstance();  try { SAXParser sp = spf.newSAXParser(); parser = sp.getXMLReader(); parser.setErrorHandler(new MyErrorHandler()); } catch (Exception e) {}   ... parse StringBuffer ... try { parser.setContentHandler(pP); parser.parse(new InputSource(new StringReader(xml.toString()))); return true; } catch (IOException e) {     e.printStackTrace(); } catch (SAXException e) {     e.printStackTrace(); } ...

So, it doesn’t appear that I can do this in the way I initially thought I could.

That being said, am I looking at this entirely wrong? What is the best method to parse multiple, discrete XML documents with the same XML handling code? I tried to ask in a more general post earlier… but, I think I was being too vague. For speed and efficiency purposes I never really looked at DOM because these XML documents are fairly large and the system receives about 1200 every few minutes. It’s just a one way send of information

To make this question too long and add to my confusion; following is a mockup of some various XML documents that I would like to have a single SAX, StAX, or ?? parser cleanly deal with.

products.xml:

<products> <product>   <id>1</id>   <name>Foo</name> <product>   <id>2</id>   <name>bar</name> </product> </products>

stores.xml:

<stores> <store>   <id>1</id>   <name>S1A</name>   <location>CA</location> </store> <store>   <id>2</id>   <name>A1S</name>   <location>NY</location> </store> </stores>

managers.xml:

<managers> <manager>   <id>1</id>   <name>Fen</name>   <store>1</store> </manager> <manager>   <id>2</id>   <name>Diz</name>   <store>2</store> </manager> </managers>
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1 Answer

  1. As I understand it, the problem is that you don’t know what format the document is prior to parsing. You could use a delegate pattern. I’m assuming you’re not validating against a DTD/XSD/etcetera and that it is OK for the DefaultHandler to have state.

    public class DelegatingHandler extends DefaultHandler {      private Map<String, DefaultHandler> saxHandlers;     private DefaultHandler delegate = null;      public DelegatingHandler(Map<String, DefaultHandler> delegates) {         saxHandlers = delegates;     }      @Override     public void startElement(String uri, String localName, String name,             Attributes attributes) throws SAXException {        if(delegate == null) {            delegate = saxHandlers.get(name);        }        delegate.startElement(uri, localName, name, attributes);     }      @Override     public void endElement(String uri, String localName, String name)             throws SAXException {         delegate.endElement(uri, localName, name);     }  //etcetera...
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