如何分解SaxParseException（cvc-pattern-valid）？

Question

What is the best way to handle validation errors of xml-data against an xs:simpleType with an xs:pattern?

eg a validation against

<xs:simpleType name="IBANIdentifier">
  <xs:restriction base="xs:string">
    <xs:pattern value="[a-zA-Z]{2,2}[0-9]{2,2}[a-zA-Z0-9]{1,30}"/>
  </xs:restriction>
</xs:simpleType>

would lead to this SaxParseException:

org.xml.sax.SAXParseException: cvc-pattern-valid: Value 'XXAA99999999999911' is 
not facet-valid with respect to pattern '[a-zA-Z]{2,2}[0-9]{2,2}[a-zA-Z0-9]{1,30}
for type 'IBANIdentifier'.

In my DefaultHandler.error(), how can I access the

• pattern
• actual value
• name of the simple type

without parsing the error-msg?

The exception does not hold this information in a structured form, AFAIKS. The parser has some state, but I dont find the information I need.

Answer 1

You can capture all the validation errors/warnings by writing your own error handler and registering with the Validator using validator.setErrorHandler(new CollectingErrorHandler(errors, shouldConsiderWarningsAsErrors));

The CollectingErrorHandler will now have access to all the validation errors. Now, there is no standard format for reporting these errors and might change from parser implementation. So stick to one parser implementation and use regex for parsing.

public final class CollectingErrorHandler implements ErrorHandler
{
    private final List<SAXException> l;

    private final boolean warningsAreErrors;

    public CollectingErrorHandler(final List<SAXException> l, final boolean shouldConsiderWarningsAsErrors)
    {
        this.l = l;
        warningsAreErrors = shouldConsiderWarningsAsErrors;
    }

    public void error(final SAXParseException e)
    {
        l.add(e);
    }

    public void fatalError(final SAXParseException e)
    {
        l.add(e);
    }

    public void warning(final SAXParseException e)
    {
        if (warningsAreErrors)
        {
            l.add(e);
        }
    }
}