Java StAX Parser - Parse XML Document


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Demo Example

Here is the input xml file we need to parse:

<?xml version="1.0"?>
<class>
   <student rollno="393">
      <firstname>dinkar</firstname>
      <lastname>kad</lastname>
      <nickname>dinkar</nickname>
      <marks>85</marks>
   </student>
   <student rollno="493">
      <firstname>Vaneet</firstname>
      <lastname>Gupta</lastname>
      <nickname>vinni</nickname>
      <marks>95</marks>
   </student>
   <student rollno="593">
      <firstname>jasvir</firstname>
      <lastname>singn</lastname>
      <nickname>jazz</nickname>
      <marks>90</marks>
   </student>
</class>

StAXParserDemo.java

package com.tutorialspoint.xml;

import java.io.FileNotFoundException;
import java.io.FileReader;
import java.util.Iterator;

import javax.xml.stream.XMLEventReader;
import javax.xml.stream.XMLInputFactory;
import javax.xml.stream.XMLStreamConstants;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.events.Attribute;
import javax.xml.stream.events.Characters;
import javax.xml.stream.events.EndElement;
import javax.xml.stream.events.StartElement;
import javax.xml.stream.events.XMLEvent;

public class StAXParserDemo {
   public static void main(String[] args) {
      boolean bFirstName = false;
      boolean bLastName = false;
      boolean bNickName = false;
      boolean bMarks = false;
      try {
         XMLInputFactory factory = XMLInputFactory.newInstance();
         XMLEventReader eventReader =
         factory.createXMLEventReader(
            new FileReader("input.txt"));

            while(eventReader.hasNext()){
               XMLEvent event = eventReader.nextEvent();
               switch(event.getEventType()){
                  case XMLStreamConstants.START_ELEMENT:
                     StartElement startElement = event.asStartElement();
                     String qName = startElement.getName().getLocalPart();
                     if (qName.equalsIgnoreCase("student")) {
                        System.out.println("Start Element : student");
                        Iterator<Attribute> attributes = startElement.getAttributes();
                        String rollNo = attributes.next().getValue();
                        System.out.println("Roll No : " + rollNo);
                     } else if (qName.equalsIgnoreCase("firstname")) {
                        bFirstName = true;
                     } else if (qName.equalsIgnoreCase("lastname")) {
                        bLastName = true;
                     } else if (qName.equalsIgnoreCase("nickname")) {
                        bNickName = true;
                     }
                     else if (qName.equalsIgnoreCase("marks")) {
                        bMarks = true;
                     }				        
                     break;
                  case XMLStreamConstants.CHARACTERS:
                     Characters characters = event.asCharacters();
                     if(bFirstName){
                        System.out.println("First Name: " 
                        + characters.getData());
                        bFirstName = false;
                     }
                     if(bLastName){
                        System.out.println("Last Name: " 
                        + characters.getData());
                        bLastName = false;
                     }
                     if(bNickName){
                        System.out.println("Nick Name: " 
                        + characters.getData());
                        bNickName = false;
                     }
                     if(bMarks){
                        System.out.println("Marks: " 
                        + characters.getData());
                        bMarks = false;
                     }
                     break;
                  case  XMLStreamConstants.END_ELEMENT:
                     EndElement endElement = event.asEndElement();
                     if(endElement.getName().getLocalPart().equalsIgnoreCase("student")){
                        System.out.println("End Element : student");
                        System.out.println();
                     }
                     break;
               }		    
            }
         } catch (FileNotFoundException e) {
            e.printStackTrace();
         } catch (XMLStreamException e) {
            e.printStackTrace();
      }
   }
}

This would produce the following result:

Start Element : student
Roll No : 393
First Name: dinkar
Last Name: kad
Nick Name: dinkar
Marks: 85
End Element : student

Start Element : student
Roll No : 493
First Name: Vaneet
Last Name: Gupta
Nick Name: vinni
Marks: 95
End Element : student

Start Element : student
Roll No : 593
First Name: jasvir
Last Name: singn
Nick Name: jazz
Marks: 90
End Element : student


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