Validate XML against DTD? XSD OK. SSCCE.

This example* shows how to validate XML against XSD.

What I would *like* to do is also offer validation
against DTD. Unforutnately, when the 'DTD' XMLConstant
is selected in the last dialog (bottom option
http://www.w3.org/TR/REC-xml), I get the output..

"Create schema from 'http://java.sun.com/dtd/JNLP-1.5.dtd'.
Exception in thread "main" java.lang.IllegalArgumentException:
No SchemaFactory that implements the schema language specified by:
http://www.w3.org/TR/REC-xml could be loaded
  at javax.xml.validation.SchemaFactory
    .newInstance(SchemaFactory.java:207)
    ..."

Does anybody demonstrate how to validate against DTD?

BTW - A quick search on ..
<http://www.google.com/search?q=XML_DTD_NS_URI+"No+SchemaFactory">
..did not reveal 'much', so I am thinking I
have 'got this all wrong'.

*
<sscce>
import java.io.IOException;

import javax.swing.JOptionPane;
import javax.swing.JComboBox;

import javax.xml.XMLConstants;
import javax.xml.validation.SchemaFactory;
import javax.xml.validation.Schema;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.stream.StreamSource;

import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;
import org.xml.sax.helpers.DefaultHandler;

import org.w3c.dom.Document;

/** Simple example of validating a structured document (XML)
against a schema (XSD).
Can anybody change this to code that will successfully
validate against a DTD? */
class XMLValidate {

  public static void main(String[] args) throws
    ParserConfigurationException,
    SAXException,
    IOException
  {

    String[] contentOptions =
    {
      // The Player JNLP is meant to pop the Java Control Panel
      // It was never intended to be valid accoring to the spec.,
      // as such, it is a good 'target' for validation, as it will
      // most likely remain 'invalid' according to the DTD/XSD
      "http://java.sun.com/products/javawebstart/apps/player.jnlp"
      ,
      // Sun's Java2D Demo - valid at time of check
      "http://java.sun.com/products/jfc/jws/Java2Demo.jnlp"
      ,
      // example of loading file from same directory
      "file:./xmlv.jnlp"
    };

    String content = null;

    String[] definitionOptions =
    {
      // the XSD from the PhySci site
      "http://www.physci.org/JNLP-6.0.xsd"
      ,
      // DTD for the Sun JNLP format
      // **can we create a schema from this?**
      "http://java.sun.com/dtd/JNLP-1.5.dtd"
      ,
      // for access from local file-system
      "file:../373XMLValidator/xmlvalidate/build/dist/JNLP-6.0.xsd"
    };

    String definition = null;

    String[] languageOptions =
    {
      // XML
      XMLConstants.W3C_XML_SCHEMA_NS_URI
      ,
      //
      XMLConstants.W3C_XML_SCHEMA_INSTANCE_NS_URI
      ,
      // RelaxNG
      XMLConstants.RELAXNG_NS_URI
      ,
      // XPath
      XMLConstants.W3C_XPATH_DATATYPE_NS_URI
      ,
      // DTD
      // No SchemaFactory that implements the schema language ..
      XMLConstants.XML_DTD_NS_URI
    };
    String language = null;

    XMLErrorHandler errorHandler = new XMLErrorHandler();

    if (args.length==2) {
      content = args[0];
      definition = args[1];
    } else if (args.length==0) {
      JComboBox contentChoice = new JComboBox (contentOptions);
      contentChoice.setEditable(true);
      JOptionPane.showMessageDialog(
        null,
        contentChoice,
        "XML URL (document)",
        JOptionPane.QUESTION_MESSAGE
        );
      content = (String)contentChoice.getSelectedItem();

      JComboBox definitionChoice = new JComboBox (definitionOptions);
      definitionChoice.setEditable(true);
      JOptionPane.showMessageDialog(
        null,
        definitionChoice,
        "XSD(/DTD) URL (schema definition)",
        JOptionPane.QUESTION_MESSAGE
        );
      definition = (String)definitionChoice.getSelectedItem();

      JComboBox languageChoice = new JComboBox (languageOptions);
      languageChoice.setEditable(true);
      JOptionPane.showMessageDialog(
        null,
        languageChoice,
        "Language - see XMLConstants",
        JOptionPane.QUESTION_MESSAGE
        );
      language = (String)languageChoice.getSelectedItem();
    } else {
      System.out.println(
        "Usage: java XMLValidate "+
        "file:./the.xml file:./the.xsd XMLConstants.languages");
      System.out.println(
        "Usage: java XMLValidate (will prompt for params)");
    }
    DocumentBuilderFactory factory =
      DocumentBuilderFactory.newInstance();
    factory.setFeature("http://xml.org/sax/features/validation", true);
    factory.setFeature("http://apache.org/xml/features/validation/schema",
true) ;
    factory.setAttribute(
      "
http://apache.org/xml/properties/schema/external-noNamespaceSchemaLocation",
      definition);

    System.out.println("Create schema from '" + definition + "'.");
    SchemaFactory schemaFactory = SchemaFactory.newInstance(language);
    Schema schema = schemaFactory.newSchema( new StreamSource(definition) );
    factory.setSchema( schema );
    System.out.println("Schema created successfully.");

    DocumentBuilder documentBuilder = factory.newDocumentBuilder();
    documentBuilder.setErrorHandler( errorHandler );

    System.out.println("Validate content from '" +
      content +
      "' against schema.");
    try {
      Document document = documentBuilder.parse( content );
    } catch (SAXException e) {
      System.err.println( e.getMessage() );
      System.err.println( "Validation failed.." );
    }
    System.out.println(
      "Total (warning, error, fatal) errors detected: " +
      errorHandler.getErrorCount() );
  }
}

class XMLErrorHandler extends DefaultHandler {

  private int errorCount=0;

    public void warning(SAXParseException exception)
      throws SAXException {
    processException(exception);
    }

    public void error(SAXParseException exception)
      throws SAXException {
    processException(exception);
    }

    public void fatalError(SAXParseException exception)
      throws SAXException {
    processException(exception);
    }

    public void processException(SAXParseException exception) {
        System.err.println(exception);
        errorCount++;
  }

    public int getErrorCount() {
    return errorCount;
  }
}
</sscce>

--
Andrew Thompson
http://www.athompson.info/andrew/

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