Validating XML Linked with XSD using XMLReader

XML Tutorials - Herong's Tutorial Examples

∟Validating XML Documents Against Specified XML Schemas

∟Validating XML Linked with XSD using XMLReader

This section provides a tutorial example on how to validate XML files that contain XSD location references with org.xml.sax.XMLReader class. It requires Xerces-J JAR files to be installed.

Another way to validate an XML file is to use the XMLReader class, if the XML file contains a reference to the XSD schema file.

But the XMLReader requires a SAX Parser implementation class. The most popular SAX Parser implementation is probably the "org.apache.xerces.parsers.SAXParser" class from the Xerces-J package. Here is my example program, XMLReaderValidator.java, which requires the Xerces-J package:

/* XMLReaderValidator.java
 * Copyright (c) 2014-2018 HerongYang.com. All Rights Reserved.
 */
import java.io.IOException;
import org.xml.sax.XMLReader;
import org.xml.sax.helpers.DefaultHandler;
import org.xml.sax.helpers.XMLReaderFactory;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;
class XMLReaderValidator {
   public static void main(String[] args) {
      String parserClass = "org.apache.xerces.parsers.SAXParser";
      String validationFeature
         = "http://xml.org/sax/features/validation";
      String schemaFeature
         = "http://apache.org/xml/features/validation/schema";
      try {
         String x = args[0];
         XMLReader r = XMLReaderFactory.createXMLReader(parserClass);
         r.setFeature(validationFeature,true);
         r.setFeature(schemaFeature,true);
         r.setErrorHandler(new MyErrorHandler());
         r.parse(x);
      } catch (SAXException e) {
         System.out.println(e.toString());
      } catch (IOException e) {
         System.out.println(e.toString());
      }
   }
   private static class MyErrorHandler extends DefaultHandler {
      public void warning(SAXParseException e) throws SAXException {
         System.out.println("Warning: ");
         printInfo(e);
      }
      public void error(SAXParseException e) throws SAXException {
         System.out.println("Error: ");
         printInfo(e);
      }
      public void fatalError(SAXParseException e) throws SAXException {
         System.out.println("Fatal error: ");
         printInfo(e);
      }
      private void printInfo(SAXParseException e) {
         System.out.println("   Public ID: "+e.getPublicId());
         System.out.println("   System ID: "+e.getSystemId());
         System.out.println("   Line number: "+e.getLineNumber());
         System.out.println("   Column number: "+e.getColumnNumber());
         System.out.println("   Message: "+e.getMessage());
      }
   }
}

Note that setFeature() method is called twice:

First call to set "http://xml.org/sax/features/validation".
Second call to set "http://apache.org/xml/features/validation/schema".

Compile and run it with JDK on dictionary_invalid_xsd.xml

herong> java XMLReaderValidator dictionary_invalid_xsd.xml

org.xml.sax.SAXException:
   SAX2 driver class org.apache.xerces.parsers.SAXParser not found
java.lang.ClassNotFoundException: org.apache.xerces.parsers.SAXParser

Okay. To resolve the error, we needed to go to http://xerces.apache.org/xerces2-j/ and download the binary distribution package, Xerces-J-bin.2.11.0.zip, of Xerces2 Java 2.11.0.

Unzip the package into \local\xerces-2_11_0 directory and make sure that xercesImpl.jar is in that directory.

Now run the XMLReaderValidator.java program again with xercesImpt.jar:

herong> java -cp .;\local\xerces-2_11_0\xercesImpl.jar \
   XMLReaderValidator dictionary_invalid_xsd.xml

org.apache.xerces.parsers.SAXParser@19bb367

Error:
   Public ID: null
   System ID: file:///C:/herong/dictionary_invalid_xsd.xml
   Line number: 7
   Column number: 22
   Message: cvc-datatype-valid.1.2.1: 'yes' is not a valid value for
      'boolean'.

Error:
   Public ID: null
   System ID: file:///C:/herong/dictionary_invalid_xsd.xml
   Line number: 7
   Column number: 22
   Message: cvc-attribute.3: The value 'yes' of attribute 'acronym' on
      element 'word' is not valid with respect to its type, 'boolean'.

Error:
   Public ID: null
   System ID: file:///C:/herong/dictionary_invalid_xsd.xml
   Line number: 11
   Column number: 31
   Message: cvc-pattern-valid: Value '23-Dec-2014' is not facet-valid
      with respect to pattern '\p{Nd}{4}-\p{Nd}{2}-\p{Nd}{2}' for type
      '#AnonType_dateupdateType'.

Error:
   Public ID: null
   System ID: file:///C:/herong/dictionary_invalid_xsd.xml
   Line number: 11
   Column number: 31
   Message: cvc-attribute.3: The value '23-Dec-2014' of attribute
      'date' on element 'update' is not valid with respect to its
      type, '#AnonType_dateupdateType'.

Error:
   Public ID: null
   System ID: file:///C:/herong/dictionary_invalid_xsd.xml
   Line number: 20
   Column number: 33
   Message: cvc-complex-type.3.2.2: Attribute 'editor' is not allowed
      to appear in element 'update'.

Error:
   Public ID: null
   System ID: file:///C:/herong/dictionary_invalid_xsd.xml
   Line number: 22
   Column number: 36
   Message: cvc-datatype-valid.1.2.1: 'no' is not a valid value for
      'boolean'.

Error:
   Public ID: null
   System ID: file:///C:/herong/dictionary_invalid_xsd.xml
   Line number: 22
   Column number: 36
   Message: cvc-attribute.3: The value 'no' of attribute 'symbol' on
      element 'word' is not valid with respect to its type, 'boolean'.

My test program, XMLReaderValidator, works! The XMLReader API and the Xerces-J package is able to automatically load the XSD file and perform the XSD schema validation while parsing the XML document.