1 - model your use class:
package com.howtodoinjava.xml.sax;
/**
* Model class. Its instances will be populated using SAX parser.
* */
public class User
{
//XML attribute id
private int id;
//XML element name
private String Name;
//XML element surname
private String SurName;
//...
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return Name;
}
public void setName(String Name) {
this.Name = Name;
}
public String getSurName() {
return SurName;
}
public void setSurName(String SurName) {
this.SurName = SurName;
}
// [...]
@Override
public String toString() {
return this.id + ":" + this.Name + ":" +this.SurName ;
}
}
2 - Build the handler by extending DefaultParser
package com.howtodoinjava.xml.sax;
import java.util.ArrayList;
import java.util.Stack;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;
public class UserParserHandler extends DefaultHandler
{
//This is the list which shall be populated while parsing the XML.
private ArrayList userList = new ArrayList();
//As we read any XML element we will push that in this stack
private Stack elementStack = new Stack();
//As we complete one user block in XML, we will push the User instance in userList
private Stack objectStack = new Stack();
public void startDocument() throws SAXException
{
//System.out.println("start of the document : ");
}
public void endDocument() throws SAXException
{
//System.out.println("end of the document document : ");
}
public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException
{
//Push it in element stack
this.elementStack.push(qName);
//If this is start of 'user' element then prepare a new User instance and push it in object stack
if ("user".equals(qName))
{
//New User instance
User user = new User();
//Set all required attributes in any XML element here itself
if(attributes != null && attributes.getLength() == 1)
{
user.setId(Integer.parseInt(attributes.getValue(0)));
}
this.objectStack.push(user);
}
}
public void endElement(String uri, String localName, String qName) throws SAXException
{
//Remove last added element
this.elementStack.pop();
//User instance has been constructed so pop it from object stack and push in userList
if ("user".equals(qName))
{
User object = this.objectStack.pop();
this.userList.add(object);
}
}
/**
* This will be called everytime parser encounter a value node
* */
public void characters(char[] ch, int start, int length) throws SAXException
{
String value = new String(ch, start, length).trim();
if (value.length() == 0)
{
return; // ignore white space
}
//handle the value based on to which element it belongs
if ("name".equals(currentElement()))
{
User user = (User) this.objectStack.peek();
user.setName(value);
}
else if ("surname".equals(currentElement()))
{
User user = (User) this.objectStack.peek();
user.setSurName(value);
}
}
/**
* Utility method for getting the current element in processing
* */
private String currentElement()
{
return this.elementStack.peek();
}
//Accessor for userList object
public ArrayList getUsers()
{
return userList;
}
}
3 - Write parser for xml file
package com.howtodoinjava.xml.sax;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.XMLReader;
import org.xml.sax.helpers.XMLReaderFactory;
public class UsersXmlParser
{
public ArrayList parseXml(InputStream in)
{
//Create a empty link of users initially
ArrayList<user> users = new ArrayList</user><user>();
try
{
//Create default handler instance
UserParserHandler handler = new UserParserHandler();
//Create parser from factory
XMLReader parser = XMLReaderFactory.createXMLReader();
//Register handler with parser
parser.setContentHandler(handler);
//Create an input source from the XML input stream
InputSource source = new InputSource(in);
//parse the document
parser.parse(source);
//populate the parsed users list in above created empty list; You can return from here also.
users = handler.getUsers();
} catch (SAXException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally {
}
return users;
}
}
4 - Test parser
package com.howtodoinjava.xml.sax;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.util.ArrayList;
public class TestSaxParser
{
public static void main(String[] args) throws FileNotFoundException
{
//Locate the file OR String
File xmlFile = new File("D:/temp/sample.xml");
//Create the parser instance
UsersXmlParser parser = new UsersXmlParser();
//Parse the file Or change to parse String
ArrayList users = parser.parseXml(new FileInputStream(xmlFile));
//Verify the result
System.out.println(users);
}
}
