Java Enterprise Best Practices

Consider Using Partial Validation

Another cornerstone of SAX-based programming is validation. Of course, in standard XML parlance, validation means ensuring that an XML document conforms to a set of constraints, usually specified by a DTD or XML schema.^[10] I state the obvious definition here, though, to challenge it.

Certainly, this traditional type of validation has its place. If you are receiving XML documents from an untrusted source, or if you allow manual editing of XML documents, it is probably a good idea to validate these documents to ensure that nothing unexpected has occurred and that your applications don’t crater on invalid XML.^[11]

Validation is achieved in SAX through the setFeature( ) method of the XMLReader object:

XMLReader reader = XMLReaderFactory.createXMLReader(  );
reader.setFeature("http://xml.org/sax/features/validation", true);
   
reader.parse(myInputSource);

If you’re using SAX through the JAXP wrapper layer, this would change to:

SAXParserFactory spf = SAXParserFactory.newInstance(  );
spf.setValidating(true);
   
SAXParser parser = spf.newSAXParser(  );
parser.parse(myInputSource, myDefaultHandler);

The problem with this blanket validation is that it is extremely process-intensive. Validating every element, every attribute, the content within elements, the resolved content of entity references, and more can take a great deal of time. While you can certainly try to validate in development and avoid validation in production, this is impossible if XML is dynamically ...