XSD Schema Validator on XML SAX Object

XML Tutorials - Herong's Tutorial Examples

∟Validating XML Documents Against Specified XML Schemas

∟XSD Schema Validator on XML SAX Object

This section provides a tutorial example on how to load a XSD schema, create an XSD validator and validate an XML SAXSource object.

Another way to use the Validator object created from a loaded XSD file is to apply it on a SAXSource object representing an XML file. Here is a tutorial example program called XsdSchemaDomValidatorWithErrorHandler.java:

/* XsdSchemaSaxValidatorWithErrorHandler.java
 * Copyright (c) 2014-2018 HerongYang.com. All Rights Reserved.
 */
import javax.xml.validation.SchemaFactory;
import javax.xml.validation.Schema;
import javax.xml.XMLConstants;
import javax.xml.transform.sax.SAXSource;
import org.xml.sax.InputSource;
import javax.xml.validation.Validator;
import java.io.*;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;
import org.xml.sax.ErrorHandler;
class XsdSchemaSaxValidatorWithErrorHandler {
  private static int errorCount = 0;
  public static void main(String[] a) {
    if (a.length<2) {
      System.out.println("Usage:");
      System.out.println("java XsdSchemaValidator schema_file_name "
        + "xml_file_name");
    } else {
      String schemaName = a[0];
      String xmlName = a[1];
      Schema schema = loadSchema(schemaName);
      validateXml(schema, xmlName);
    }
  }
  public static void validateXml(Schema schema, String xmlName) {
    try {
      // creating a Validator instance
      Validator validator = schema.newValidator();
      System.out.println();
      System.out.println("Validator Class: "
        + validator.getClass().getName());

      // setting my own error handler
      validator.setErrorHandler(new MyErrorHandler());

      // preparing the XML file as a SAX source
      SAXSource source = new SAXSource(
        new InputSource(new java.io.FileInputStream(xmlName)));

      // validating the SAX source against the schema
      validator.validate(source);
      System.out.println();
      if (errorCount>0) {
        System.out.println("Failed with errors: "+errorCount);
      } else {
        System.out.println("Passed.");
      }

    } catch (Exception e) {
      // catching all validation exceptions
      System.out.println();
      System.out.println(e.toString());
    }
  }
  public static Schema loadSchema(String name) {
    Schema schema = null;
    try {
      String language = XMLConstants.W3C_XML_SCHEMA_NS_URI;
      SchemaFactory factory = SchemaFactory.newInstance(language);
      schema = factory.newSchema(new File(name));
    } catch (Exception e) {
      System.out.println(e.toString());
    }
    return schema;
  }
  static class MyErrorHandler implements ErrorHandler {
    public void fatalError( SAXParseException e )
       throws SAXException {
      System.out.println(e.toString());
      throw e;
    }
    public void error( SAXParseException e ) throws SAXException {
      System.out.println(e.toString());
      errorCount++;
      // continue with validation process
      // throw e;
    }
    public void warning( SAXParseException e ) throws SAXException {
      System.out.println(e.toString());
    }
  }
}

Let's try it with JDK on first_html_extra_attribute.xml:

herong> java XsdSchemaSaxValidatorWithErrorHandler \
   first_html.xsd first_html_extra_attribute.xml

Validator Class:
   com.sun.org.apache.xerces.internal.jaxp.validation.ValidatorImpl

org.xml.sax.SAXParseException; lineNumber: 3; columnNumber: 25;
cvc-type.3.1.1: Element 'body' is a simple type, so it cannot have
attributes, excepting those whose namespace name is identical to
'http://www.w3.org/2001/XMLSchema-instance' and whose [local name]
is one of 'type', 'nil', 'schemaLocation' or
'noNamespaceSchemaLocation'. However, the attribute, 'bgcolor' was
found.

org.xml.sax.SAXParseException; lineNumber: 5; columnNumber: 8;
cvc-type.3.1.2: Element 'body' is a simple type, so it must have
no element information item [children].

Failed with errors: 2

Nice. XsdSchemaSaxValidatorWithErrorHandler.java produces error messages with line number and column number, better than XsdSchemaDomValidatorWithErrorHandler.java.