Loading External XML Parsers with SAXParserFactory

<< XSD (XML Schema Definition) - XML Validation

<< JDK (Java Development Kit) Tutorials

This section provides a tutorial example on how to load external XML parsers using the SAXParserFactory.newInstance() method.

The Xerces-J package can also be loaded by the SAXParserFactory.newInstance() method. Here is my SAXValidator.java:

/**
 * SAXValidator.java
 * Copyright (c) 2002 by Dr. Herong Yang
 */
import java.io.File;
import java.io.IOException;
import javax.xml.parsers.SAXParserFactory;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.ParserConfigurationException;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;
import org.xml.sax.helpers.DefaultHandler;
class SAXValidator {
   public static void main(String[] args) {
      String schemaFeature 
         = "http://apache.org/xml/features/validation/schema";
      try {
      	 File x = new File(args[0]);
         SAXParserFactory f = SAXParserFactory.newInstance();
         System.out.println(f.toString());
         f.setValidating(true);
         f.setFeature(schemaFeature,true);
         SAXParser p = f.newSAXParser();
         System.out.println(p.toString());
         DefaultHandler h = new MyErrorHandler();
         p.parse(x,h);
      } catch (ParserConfigurationException e) {
         System.out.println(e.toString()); 
      } 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("Fattal 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 the schema feature to the SAXParserFactory object.

Now if you run the program with:

java -cp . SAXValidator dictrionary_invalid_xsd.xml

You will get:

org.apache.crimson.jaxp.SAXParserFactoryImpl@1004901
org.xml.sax.SAXNotRecognizedException: Feature: http://apache.org/xml
/features/validation/schema

Note that the crimson package was loaded from the J2SDK library, and it doesn't support XSD validation.

But if you run the program with:

java -cp .;\local\xerces-2_3_0\xercesImpl.jar SAXValidator
   dictrionary_invalid_xsd.xml

You will get:

org.apache.xerces.jaxp.SAXParserFactoryImpl@f72617
org.apache.xerces.jaxp.SAXParserImpl@173831b
...

Note that the xerces package was loaded, and XSD validation was performed.

Last update: 2006.

Sections in This Chapter

XML XSD Schema Validation with Xerces

XML XSD Schema Validation Test Result

Loading External XML Parsers with SAXParserFactory