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, 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 validatin 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 1.8:

C:\herong\xml>java XsdSchemaDomValidatorWithErrorHandler 
   first_html.xsd first_html.xml

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

Passed.

Cool. My validator, XsdSchemaDomValidatorWithErrorHandler.java, works.

Last update: 2014.

Table of Contents

 About This Book

 Introduction of XML (eXtensible Markup Language)

 XML File Syntax

 XML File Browsers

 DOM (Document Object Model) Programming Interface

 SAX (Simple API for XML) Programming Interface

 DTD (Document Type Definition) Introduction

 Syntaxes of DTD Statements

 Validating an XML Document against the Specified DTD Document Type

 XSD (XML Schema Definition) Introduction

 Syntaxes of XSD Statements

Validating XML Documents Against Specified XML Schemas

XSD Schema Validator on XML DOM Object

 XSD Schema Validator on XML DOM Object - Errors

 XSD Schema Validator on XML SAX Object

 SAXParseException - 'xsi:noNamespaceSchemaLocation' Not Allowed

 Validating XML Linked with XSD using XMLReader

 XSL (Extensible Stylesheet Language) Introduction

 XSLT (XSL Transformations) Introduction

 Java Implementation of XSLT

 XPath (XML Path) Language

 XSLT Elements as Programming Statements

 Control and Generate XML Element in the Result

 XML Notepad - XML Editor

 XML Tools Plugin for Notepad++

 XML 1.1 Changes and Parsing Examples

 Outdated Tutorials

 References

 PDF Printing Version