XML Tutorials - Herong's Tutorial Examples - v5.25, by Herong Yang
DOMValidator.java - Validating XML with DTD using DOM
This section provides a tutorial example on how to use DOM API provided in JDK 1.4 to write a Java program to validate an XML document against the specified DTD document type.
JDK offers a document builder interface, javax.xml.parsers.DocumentBuilder, to represent classes that can parse XML files into document objects described in the Document Object Model (DOM). See my notes on DOM for more details.
The document builder also supports DTD validation during the parsing process. To do this:
Here is a sample program, DOMValidator, that shows you how to use a document builder class to validate XML files against the specified DTD statements.
/* DOMValidator.java * Copyright (c) 2014-2018 HerongYang.com, All Rights Reserved. */ import java.io.File; import java.io.IOException; import javax.xml.parsers.DocumentBuilderFactory; import javax.xml.parsers.DocumentBuilder; import javax.xml.parsers.ParserConfigurationException; import org.w3c.dom.Document; import org.xml.sax.SAXException; import org.xml.sax.SAXParseException; import org.xml.sax.ErrorHandler; import org.xml.sax.helpers.DefaultHandler; class DOMValidator { public static void main(String[] args) { try { File x = new File(args[0]); DocumentBuilderFactory f = DocumentBuilderFactory.newInstance(); f.setValidating(true); // Default is false DocumentBuilder b = f.newDocumentBuilder(); // ErrorHandler h = new DefaultHandler(); ErrorHandler h = new MyErrorHandler(); b.setErrorHandler(h); Document d = b.parse(x); } 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 implements ErrorHandler { 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("Fatal 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()); } } }
To test DOMValidator, I created the following XML file with DTD statements, invalid_dtd.xml:
<?xml version="1.0"?> <!-- invalid_dtd.xml - Copyright (c) 2002-2014 HerongYang.com. All Rights Reserved. --> <!DOCTYPE dictionary [ <!ELEMENT dictionary (note, word+)> <!ELEMENT note ANY> <!ELEMENT word (update?, name, definition+, usage*)> <!ELEMENT update EMPTY> <!ATTLIST update date CDATA #REQUIRED editor CDATA #IMPLIED > <!ELEMENT name (#PCDATA)> <!ATTLIST name is_acronym (true | false) "false"> <!ELEMENT definition (#PCDATA)> <!ELEMENT usage (#PCDATA | i)*> <!ELEMENT i (#PCDATA)> <!ENTITY herong "Herong Yang"> ]> <dictionary> <note>Copyright (c) 2002-2014 by &herong;</note> <word> <name is_acronym="true" language="EN">POP</name> <definition>Post Office Protocol</definition> <definition>Point Of Purchase</definition> </word> <word> <update date="2014-12-23"/> <name is_acronym="yes">XML</name> <definition>eXtensible Markup Language</definition> <note>XML comes from SGML</note> </word> <word> <update editor="Herong Yang"/> <name>markup</name> <definition>The amount added to the cost price to calculate the selling price - <i>Webster</i></definition> </word> </dictionary>
Run the sample Java program in JDK (Java Development Kit), I get:
herong> java DOMValidator invalid_dtd.xml Error: Public ID: null System ID: file:/C:/herong/invalid_dtd.xml Line number: 24 Column number: 41 Message: Attribute "language" must be declared for element type "name". Error: Public ID: null System ID: file:/C:/herong/invalid_dtd.xml Line number: 30 Column number: 26 Message: Attribute "is_acronym" with value "yes" must have a value from the list "true false ". Error: Public ID: null System ID: file:/C:/herong/invalid_dtd.xml Line number: 33 Column number: 9 Message: The content of element type "word" must match "(update?,name,definition+,usage*)". Error: Public ID: null System ID: file:/C:/herong/invalid_dtd.xml Line number: 35 Column number: 33 Message: Attribute "date" is required and must be specified for element type "update". Error: Public ID: null System ID: file:/C:/herong/invalid_dtd.xml Line number: 38 Column number: 48 Message: The content of element type "definition" must match "null"
This is perfect. It tells you where the error is, and why it's an error.
Table of Contents
Introduction of XML (eXtensible Markup Language)
DOM (Document Object Model) Programming Interface
SAX (Simple API for XML) Programming Interface
DTD (Document Type Definition) Introduction
►Validating an XML Document against the Specified DTD Document Type
►DOMValidator.java - Validating XML with DTD using DOM
SAXValidator.java - Validating XML with DTD using SAX
XSD (XML Schema Definition) Introduction
Validating XML Documents Against Specified XML Schemas
XSL (Extensible Stylesheet Language) Introduction
XSLT (XSL Transformations) Introduction
XSLT Elements as Programming Statements
Control and Generate XML Element in the Result
PHP Extensions for XML Manipulation
Processing XML with Python Scripts
XML Tools Plugin for Notepad++
XML Plugin Packages for Atom Editor