XML Tutorials - Herong's Tutorial Examples - v5.25, by Herong Yang
SAXValidator.java - Validating XML with DTD using SAX
This section provides a tutorial example on how to use SAX API provided in JDK 1.4 to write a Java program to validate an XML document against the specified DTD document type.
Actually, SAX and DOM are sharing the same XML validation implementation. In this implementation, error events are fired during the parsing process. Application programs that are interested in validation errors must implement the error event handlers defined in the org.xml.sax.ErrorHandler interface.
In the SAX design, the ErrorHandler interface is integrated into the DefaultHandler class. Application programs just need to extend DefaultHandler and override those error event handlers.
Here is my SAX based XML validation program, SAXValidator.java:
/* SAXValidator.java * Copyright (c) 2014-2018 HerongYang.com, All Rights Reserved. */ import java.io.File; import java.io.IOException; import javax.xml.parsers.SAXParserFactory; import javax.xml.parsers.SAXParser; import javax.xml.parsers.ParserConfigurationException; import org.xml.sax.Attributes; import org.xml.sax.SAXException; import org.xml.sax.SAXParseException; import org.xml.sax.helpers.DefaultHandler; class SAXValidator { public static void main(String[] args) { try { File x = new File(args[0]); SAXParserFactory f = SAXParserFactory.newInstance(); f.setValidating(true); // Default is false SAXParser p = f.newSAXParser(); DefaultHandler h = new MyErrorHandler(); p.parse(x,h); } 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 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("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()); } } }
Note that:
Run "java SAXValidator invalid_dtd.xml" in JDK, you will get the same output as DOMValidator.java described in the previous section.
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