Question

After searching for the best approach to validating my XML against an XSD, I came across java.xml.validator.

I started off by using the example code from the API and adding my own ErrorHandler

// parse an XML document into a DOM tree
DocumentBuilder parser = DocumentBuilderFactory.newInstance().newDocumentBuilder();
Document document = parser.parse(new File("instance.xml"));

// create a SchemaFactory capable of understanding WXS schemas
SchemaFactory factory = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);

// load a WXS schema, represented by a Schema instance
Source schemaFile = new StreamSource(new File("mySchema.xsd"));
Schema schema = factory.newSchema(schemaFile);

// create a Validator instance, which can be used to validate an instance document
Validator validator = schema.newValidator();

// Add a custom ErrorHandler
validator.setErrorHandler(new XsdValidationErrorHandler());

// validate the DOM tree
try {
    validator.validate(new DOMSource(document));
} catch (SAXException e) {
    // instance document is invalid!
}

...

private class XsdValidationErrorHandler implements ErrorHandler {
    @Override
    public void warning(SAXParseException exception) throws SAXException {
        throw new SAXException(exception.getMessage());
    }

    @Override
    public void error(SAXParseException exception) throws SAXException {
        throw new SAXException(exception.getMessage());
    }

    @Override
    public void fatalError(SAXParseException exception) throws SAXException {
        throw new SAXException(exception.getMessage());
    }
}

This works fine, however, the message passed to my XsdValidationErrorHandler is doesn’t give me any indication of exactly where in the document the offending XML is:

"org.xml.sax.SAXParseException: cvc-complex-type.2.4.a: Invalid content was found starting with element 'X'. One of '{Y}' is expected."

Is there a way for me to override or plug-in another section of Validator, so that I can define my own error messages sent to the ErrorHandler without having to rewrite all of the code?

Should I be using a different library?

Answer 1

Try catching SaxParseException, it’s a descendant of SaxException. If you get one of them it has methods getLineNumber(), getColumnNumber() etc.