XSD Schema Validator on XML DOM Object

XML Tutorials - Herong's Tutorial Examples

∟Validating XML Documents Against Specified XML Schemas

∟XSD Schema Validator on XML DOM Object

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

If you want to validate an XML presented as a DOM object against an XSD schema, you can load the XSD file and create a Schema object first. Then create a Validator object to validate the DOM object.

Here is a tutorial example program called XsdSchemaDomValidatorWithErrorHandler.java that validates an XML file against an XSD file using the DOM interface:

/* XsdSchemaDomValidatorWithErrorHandler.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.parsers.DocumentBuilderFactory;
import javax.xml.parsers.DocumentBuilder;
import org.w3c.dom.Document;
import javax.xml.validation.Validator;
import javax.xml.transform.dom.DOMSource;
import java.io.File;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;
import org.xml.sax.ErrorHandler;
class XsdSchemaDomValidatorWithErrorHandler {
  private static int errorCount = 0;
  public static void main(String[] a) {
    if (a.length<2) {
      System.out.println("Usage:");
      System.out.println("java XsdSchemaDomValidatorWithErrorHandler "
        + "schema_file_name xml_file_name");
    } else {
      String schemaName = a[0];
      String xmlName = a[1];
      Schema schema = loadSchema(schemaName);
      Document document = parseXmlDom(xmlName);
      validateXml(schema, document);
    }
  }
  public static void validateXml(Schema schema, Document document) {
    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());

      // validating the document against the schema
      validator.validate(new DOMSource(document));
      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;
  }
  public static Document parseXmlDom(String name) {
    Document document = null;
    try {
      DocumentBuilderFactory factory
         = DocumentBuilderFactory.newInstance();
      DocumentBuilder builder = factory.newDocumentBuilder();
      document = builder.parse(new File(name));
    } catch (Exception e) {
      System.out.println(e.toString());
    }
    return document;
  }
  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());
    }
  }
}

In order to test XsdSchemaDomValidatorWithErrorHandler.java, here is a sample XSD file, first_html.xsd:

<?xml version="1.0" encoding="utf-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
  elementFormDefault="qualified" attributeFormDefault="unqualified">
 <xs:element name="html" type="htmlType"/>
 <xs:complexType name="htmlType">
  <xs:sequence>
   <xs:element name="body" type="xs:string"/>
  </xs:sequence>
 </xs:complexType>
</xs:schema>

Here is an XML file, first_html.xml, that conforms with the above XSD:

<?xml version="1.0" encoding="utf-8"?>
<html>
<body>My first HTML document in XML format.</body>
</html>

Here is test result with JDK (Java Development Kit).

herong> java XsdSchemaDomValidatorWithErrorHandler \
   first_html.xsd first_html.xml

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

Passed.