SAX (Simple API for XML) Implementation in JDK

<< SAX (Simple API for XML)

<< JDK (Java Development Kit) Tutorials

This section provides a tutorial example on how to write a simple program to find out what are the implementation classes for the SAX interfaces in JDK. The key is to call the javax.xml.parsers.SAXParserFactory.newInstance() method.

What is SAX (Simple API for XML)? SAX is an Application Programming Interface (API) that allows the parser to fire events based on the XML structure while parsing an XML file. It allows application programs to process the contents of the XML by handling the events fired by the parser.

SAX has been implemented in Java in J2SDK 1.4.1_01, which is already installed on my system. So I am ready to play with XML files through SAX in Java.

The first task is to find out how JDK supports SAX. To do this, I wrote this simple program here, SAXClassChecker.java, to show what are the implementation classes for the SAX interfaces:

/**
 * SAXClassChecker.java
 * Copyright (c) 2002 by Dr. Herong Yang
 */
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.helpers.DefaultHandler;
import org.xml.sax.SAXException;
class SAXClassChecker {
   public static void main(String[] args) {
      try {
      	 File x = new File(args[0]);
         SAXParserFactory f = SAXParserFactory.newInstance();
         System.out.println(f.toString());
         SAXParser p = f.newSAXParser();
         System.out.println(p.toString());
         DefaultHandler h = new DefaultHandler();
         System.out.println(h.toString());
         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()); 
      }
   }
}

Run the program as: java SAXClassChecker hello.xml, you will get:

org.apache.crimson.jaxp.SAXParserFactoryImpl@1c78e57
org.apache.crimson.jaxp.SAXParserImpl@1e63e3d
org.xml.sax.helpers.DefaultHandler@1be2d65

Note that:

• javax.xml.parsers.SAXParserFactory.newInstance() method is used to create a new fatory instance using the factory implementation class, org.apache.crimson.jaxp.SAXParserFactoryImpl.
• javax.xml.parsers.SAXParserFactory.newSAXParser() method is used to create a new parser instance using the parser implementation class, org.apache.crimson.jaxp.SAXParserImpl.
• javax.xml.parsers.SAXParser.parse() method is used to invoke the parsing process. It requires two parameters, a File object representing the XML file, and an parsing event handler object.
• org.xml.sax.helpers.DefaultHandler is dummy handler, which handles all the events fired by the parser, but does nothing. This is why we are getting nothing from the XML file when running this program.

Last update: 2006.

Sections in This Chapter

SAX (Simple API for XML) Implementation in JDK

SAX Content Handler Interface

SAXBrowser.java - SAX Based XML Browser