XSD Validation in Java

Part:   1   2  3 

This tutorial describes:

• Validation with XMLReader
• Using SAXParserFactory to Load Parsers

Validation with XMLReader

Unfortunately, I couldn't find any XML parsers provided in J2SDK 1.4.1_02 that can validate XML structure against XSD rules. So I downloaded one of the most popular XML parsers in the public domain, xerces-j 2.3.0, at: http://xml.apache.org/dist/xerces-j.

Once I downloaded Xerces-J-bin.2.3.0.zip, I unzipped it into \local\xerces-2_3_0 directory. Make sure that xercesImpt.jar is in that directory.

Now I am ready to write a simple Java program to use "org.apache.xerces.parsers.SAXParser" to validate any XML files against the specified XSD files:

/**
 * XMLReaderValidator.java
 * Copyright (c) 2002 by Dr. Herong Yang
 */
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("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());
      }
   }
}

Here is an XML file, dictionary_invalid_xsd.xml:

<?xml version="1.0"?>
<dictionary xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
 xsi:noNamespaceSchemaLocation="dictionary.xsd">
<!-- dictionary_invalid_xsd.xml
     Copyright (c) 2002 by Dr. Herong Yang
-->
 <word acronym="yes">
  <name>XML</name>
  <definition reference="Herong's Notes">eXtensible Markup 
Language.</definition>
  <update date="23-Dec-2003"/>
 </word>
 <word symbol="true">
  <name><</name>
  <definition>Mathematical symbol representing the "less than" logical 
operation, like: 1<2.</definition>
  <definition>Reserved symbol in XML representing the beginning of 
tags, like: <![CDATA[<p>Hello world!</p>]]>
  </definition>
  <update editor="Herong Yang"/>
 </word>
 <word symbol="no" acronym="false">
  <name>extensible</name>
  <definition>Capable of being extended.</definition>
 </word>
</dictionary>

(Continued on next part...)

Part:   1   2  3