Validating XML Documents with Schema Locations

XSD Tutorials - Herong's Tutorial Examples

∟XML Schema Location and Namespace in XML Documents

∟Validating XML Documents with Schema Locations - JAXP

This section describes a test on using JAXP standard parser interface to validate an XML document with schema location assigned inside the XML document.

Note that JAXP 1.4 does not support schema validation on the XML parser classes interfaces any more. The following testing program, XmlSchemaValidator.java, worked correctly on older JAXP releases:

/* XmlSchemaValidator.java
 - Copyright (c) 2002-2013 HerongYang.com. All Rights Reserved.
 */
import javax.xml.parsers.SAXParserFactory;
import javax.xml.parsers.SAXParser;
import org.xml.sax.helpers.DefaultHandler;
import java.io.File;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;
import org.xml.sax.ErrorHandler;
class XmlSchemaValidator {
  private static int errorCount = 0;
  public static void main(String[] a) {
    if (a.length<1) {
      System.out.println("Usage:");
      System.out.println("java XmlSchemaValidator xml_file_name");
    } else {
      String name = a[0];

      // parsing the XML file
      validateXml(name);
    }
  }
  public static void validateXml(String name) {
    try {
      String schemaFeature
         = "http://apache.org/xml/features/validation/schema";

      // getting the default implementation of SAX parser
      SAXParserFactory factory
         = SAXParserFactory.newInstance();

      // setting the factory for XML schema validation
      // this will not work any more in JAXP 1.4
      factory.setFeature(schemaFeature, true);

      SAXParser parser = factory.newSAXParser();
      System.out.println();
      System.out.println("Factory Class: "
        + factory.getClass().getName());
      System.out.println("Parser Class: "
        + parser.getClass().getName());

      System.out.println();
      System.out.println("Parsing and validating: "+name);
      parser.parse(new File(name), new MyHandler());
      System.out.println();
      if (errorCount>0) {
        System.out.println("Failed with errors: "+errorCount);
      } else {
        System.out.println("Passed.");
      }

    } catch (Exception e) {
      // catching all exceptions
      System.out.println();
      System.out.println(e.toString());
    }
  }
  private static class MyHandler extends DefaultHandler {
    public void warning(SAXParseException e) throws SAXException {
       System.out.println("Warning: ");
       printException(e);
    }
    public void error(SAXParseException e) throws SAXException {
       System.out.println("Error: ");
       printException(e);
    }
    public void fatalError(SAXParseException e) throws SAXException {
       System.out.println("Fattal error: ");
       printException(e);
    }
    private void printException(SAXParseException e) {
      errorCount++;
      System.out.println("   Line number: "+e.getLineNumber());
      System.out.println("   Column number: "+e.getColumnNumber());
      System.out.println("   Message: "+e.getMessage());
      System.out.println();
    }
  }
}

If you try the above program on hello_xsd_no_namespace.xml that has schema location assigned, you will still get a validation error:

herong> java XmlSchemaValidator hello_xsd_no_namespace.xml

Factory Class: com.sun.org.apache.xerces.internal.jaxp.SAXParserFactoryImpl
Parser Class: com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl

Parsing and validating: hello_xsd_no_namespace.xml
Error:
   Line number: 3
   Column number: 44
   Message: cvc-elt.1: Cannot find the declaration of element 'p'.

Failed with errors: 1

Conclusion: This test proves that JAXP 1.4 is no longer supports the schema validation feature identified as, "http://apache.org/xml/features/validation/schema", while parsing XML documents.