to the main page about the tutorial  THE XML REVOLUTION  -  TECHNOLOGIES FOR THE FUTURE WEB back up next

SAX events

The following Java program traces all SAX events generated by parsing the recipe collection: 

import java.io.*;
import org.xml.sax.*;
import org.xml.sax.helpers.*;
import org.apache.xerces.parsers.SAXParser;

public class Trace extends DefaultHandler {

  int indent;

  void printIndent() {
    for (int i=0; i<indent; i++) System.out.print("-");
  }

  public void startDocument() {
    System.out.println("start document");
  }

  public void endDocument() {
    System.out.println("end document");
  }

  public void startElement(String uri, String localName,
                           String qName, Attributes attributes) {
    printIndent();
    System.out.println("starting element: " + qName);
    indent++;
  }

  public void endElement(String uri, String localName, 
                         String qName) {
    indent--;
    printIndent();
    System.out.println("end element: " + qName);
  }

  public void ignorableWhitespace(char[] ch, int start, int length) {
    printIndent();
    System.out.println("whitespace, length " + length);
  }

  public void processingInstruction(String target, String data) {
    printIndent();
    System.out.println("processing instruction: " + target);
  }

  public void characters(char[] ch, int start, int length){
    printIndent();
    System.out.println("character data, length " + length);
  }

  public static void main(String[] args) {
    Trace t = new Trace();
    SAXParser p = new SAXParser();
    p.setContentHandler(t);
    try { p.parse(args[0]); } 
    catch (Exception e) {e.printStackTrace();}
  }
}

The output is (abbreviated with ...): 

start document
processing instruction: dsd
starting element: collection
-character data, length 3
-starting element: description
--character data, length 47
-end element: description
-character data, length 3
-starting element: recipe
--character data, length 5
...
-end element: recipe
-character data, length 1
end element: collection
end document

back COPYRIGHT © 2000-2003 ANDERS MØLLER & MICHAEL I. SCHWARTZBACH next