How to validate a xml file against a given xsd file while parsing it with a sax parser?

Question

I want to parse a xml file using a SAXParser or XMLReader and verify that the file conforms to a specific xsd file (new File( "example.xsd" )).

It's easy to

1. do the validation against a xsd file in an extra step using a Validator like in this SO answer.

2. to validate while parsing by specifying the name of the xsd as "http://apache.org/xml/properties/schema/external-noNamespaceSchemaLocation" like in this SO answer.

But how can I validate against a new File( "example.xsd" ) while parsing?

Answer 1

Assuming Java 5 or above, set the schema on the SAXParserFactory:

SchemaFactory schemaFactory = SchemaFactory
    .newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
Schema schema = schemaFactory.newSchema(new File("myschema.xsd"));
SAXParserFactory saxFactory = SAXParserFactory.newInstance();
saxFactory.setSchema(schema);
SAXParser parser = saxFactory.newSAXParser();
parser.parse("data.xml", new DefaultHandler() {
  // TODO: other handler methods
  @Override
  public void error(SAXParseException e) throws SAXException {
    throw e;
  }
});

You handle validation errors by overriding the error method on your handler and acting as you see fit.