SAX Parser: How to Read an XML File in Java

Sax parser  Sax is the most popular parser of the latest DOM, unlike DOM, Sax works differently, it doesn't load XML into memory before it processes it, and it doesn't create any type of XML object. SAX is a good choice for parsing a large xml file because it consumes less memory.

SAX Parser uses three methods to parse and read an xml:

startElement(): Whenever SAX parser encounters an opening tag '<', it calls startElement().

endElement(): at  whenever SAX parser encounters a closing tag '>', it calls startElement().

characters(): This method is called when the SAX parser finds text between the opening and closing tag

These three methods are responsible for parsing xml, the programmer uses them to parse, read, or extract information from the code.

Extract text from xml file in java

To test java code, You have to create a simple XML file that you will use to display its contents in the console:

 
< Contacts> 
 < person id="1"> 
 < Name> encoder 
 < First name> java 
 < mobile> 054124587 
 < Email> codeurjava@gmail.com 
  
 < person id="2"> 
 < Name> encoder 
 < First name> c++ 
 < mobile> 062148795 
 < Email> codeurcplusplus@gmail.com 
  
 

The java:

import javax.xml.parsers.SAXParser; 
import javax.xml.parsers.SAXParserFactory; 
import org.xml.sax.Attributes; 
import org.xml.sax.SAXException; 
import org.xml.sax.helpers.DefaultHandler; 
 
public class ReadFileXML{
 
 public static void main(String argv[]) {
 
 try {
 //Get sax parser
 SAXParserFactory spfactory = SAXParserFactory.newInstance(); 
 //Get an instance of the parser
 SAXParser saxParser = spfactory.newSAXParser(); 
 
 /*all three methods are declared in the DefaltHandler /> corp DefaultHandler handler = new DefaultHandler() {
 
 boolean bnom = false; 
 boolean bprefirst name = false; 
 boolean bmobile = false; 
 boolean bemail = false; 
 
 /*this method is invoked whenever Parser encounters
 an opening tag '<' */
 public void startElement(String uri, String localName,
 String qName,Attributes attributes) throws SAXException{
 
 if (qName.equalsIgnoreCase("name")) {
 bnom = true; 
 }
 
 if (qName.equalsIgnoreCase("firstname")) {
 bfirstname = true; 
 }
 
 if (qName.equalsIgnoreCase("mobile")) {
 bmobile = true; 
 }
 
 if (qName.equalsIgnoreCase("email")) {
 bemail = true; 
 }
 }
 
 /*this method is invoked whenever parser encounters
 a closing tag '>' */
 public void endElement(String uri, String localName,
 String qName) throws SAXException {
 
 if (qName.equalsIgnoreCase("name")) {
 bnom = false; 
 }
 
 if (qName.equalsIgnoreCase("firstname")) {
 bfirstname = false; 
 }
 
 if (qName.equalsIgnoreCase("mobile")) {
 bmobile = false; 
 }
 
 if (qName.equalsIgnoreCase("email")) {
 bemail = false; 
 }
 }

 /*prints data stored between '<' and '>' */
 public void characters(char ch[], int start,
 int length) throws SAXException {
 
 if (bnom) {
 System.out.println("Name: " + 
 new String(ch,  start, length)); 
 bnom = false; 
 }
 
 if (bprename) {
 System.out.println("First name: " +
 new String(ch, start, length)); 
 bfirst name = false; 
 }
 
 if (bmobile) {
 System.out.println("Mobile : " + 
 new String(ch, start, length)); 
 bmobile = false; 
 }
 
 if (bemail) {
 System.out.println("Email : " + 
 new String(ch, start, length)); 
 bemail = false; 
 } 
 }
 
 }; 
 
 saxParser.parse("exemple.xml", handler); 
 
 } catch (Exception e) {
 e.printStackTrace(); 
 }
 }
}

Execution:

Last name: coder
First name: java
Mobile: 054124587
Email: codeurjava@gmail.com

Last name: coder
First name:  c++
Mobile: 062148795
Email: codeurcplusplus@gmail.com