stax xml validation - stax

Question

I know I can validate xml-file when I use sax. But can I validate when I use Stax?

Answer 1

There are two ways of XML validation possible with SAX and DOM:
validate alone - via Validator.validate()
validate during parsing - via DocumentBuilderFactory.setSchema() and SAXParserFactory.setSchema()
With StAX, validation is possible, but only the first way of doing it.
You can try something like this:
import javax.xml.validation.*;
import javax.xml.transform.stax.*;
import javax.xml.stream.*;
import javax.xml.*;
import java.io.*;
public class StaxValidation {
public static void main (String args[]) throws Exception {
XMLStreamReader reader = XMLInputFactory.newInstance().createXMLStreamReader(new FileInputStream("test.xml"));
SchemaFactory factory = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
Schema schema = factory.newSchema(new File("test.xsd"));
Validator validator = schema.newValidator();
validator.validate(new StAXSource(reader));
//no exception thrown, so valid
System.out.println("Document is valid");
}
}

Answer 2

You can parse and validate with StAX in one pass. Use javax.xml.stream.util.StreamReaderDelegate:
XMLStreamReader reader = XMLInputFactory.newInstance().createXMLStreamReader(new FileInputStream ("test.xml"));
reader = new StreamReaderDelegate(reader) {
public int next() throws XMLStreamException {
int n = super.next();
// process event
return n;
}};
SchemaFactory factory = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
Schema schema = factory.newSchema(new File("test.xsd"));
Validator validator = schema.newValidator();
validator.validate(new StAXSource(reader));
Validator reads test.xml calling reader.next() and you process parsing events as usual.

Answer 3

There is no standard way to do this. However, there's an API extension called StAX2 which support validation using Sun's MSV (multi schema validation). I would recommend to use the Woodstox StAX2 implementation.
http://woodstox.codehaus.org/