SAX is a stream-based processor. Only a tiny part is stored in memory at any time and the XML stream can be sniffed by implementing callback code for events like tagStarted() etc.
- It is an event-based parser.
- It parses the file as it reads it.
- It does not require huge memory as the whole document is not stored at once.
- It is read-only i.e. can't insert or delete any node.
- It is preferred when memory content is large.
- It reads the XML file from top to bottom and it does not support backward navigation.
Content of Employee.java
package com.t4b.parser.sax.test;
public class Employee {
private String name;
private int age;
private int id;
private String type;
public Employee() {
}
public Employee(String name, int id, int age, String type) {
this.name = name;
this.age = age;
this.id = id;
this.type = type;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
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 getType() {
return type;
}
public void setType(String type) {
this.type = type;
}
public String toString() {
StringBuffer sb = new StringBuffer();
sb.append("Employee Details - ");
sb.append("Name:" + getName());
sb.append(", ");
sb.append("Type:" + getType());
sb.append(", ");
sb.append("Id:" + getId());
sb.append(", ");
sb.append("Age:" + getAge());
sb.append(".");
return sb.toString();
}
}
Content of SAXParserTest.java
package com.t4b.parser.sax.test;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import javax.xml.parsers.ParserConfigurationException;
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 SAXParserTest extends DefaultHandler {
List<Employee> myEmpls;
private String tempVal;
private Employee tempEmp;
public SAXParserTest() {
myEmpls = new ArrayList<Employee>();
}
public void runExample() {
parseDocument();
printData();
}
private void parseDocument() {
SAXParserFactory spf = SAXParserFactory.newInstance();
try {
SAXParser sp = spf.newSAXParser();
sp.parse("employees.xml", this);
} catch (SAXException se) {
se.printStackTrace();
} catch (ParserConfigurationException pce) {
pce.printStackTrace();
} catch (IOException ie) {
ie.printStackTrace();
}
}
private void printData() {
System.out.println("No of Employees '" + myEmpls.size() + "'.");
Iterator<Employee> it = myEmpls.iterator();
while (it.hasNext()) {
System.out.println(it.next().toString());
}
}
public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
System.out.println("start - " + qName + "\n");
tempVal = "";
if (qName.equalsIgnoreCase("Employee")) {
tempEmp = new Employee();
tempEmp.setType(attributes.getValue("type"));
}
}
public void characters(char[] ch, int start, int length) throws SAXException {
tempVal = new String(ch, start, length);
}
public void endElement(String uri, String localName, String qName) throws SAXException {
System.out.println("end - " + qName);
if (qName.equalsIgnoreCase("Employee")) {
myEmpls.add(tempEmp);
} else if (qName.equalsIgnoreCase("Name")) {
tempEmp.setName(tempVal);
} else if (qName.equalsIgnoreCase("Id")) {
tempEmp.setId(Integer.parseInt(tempVal));
} else if (qName.equalsIgnoreCase("Age")) {
tempEmp.setAge(Integer.parseInt(tempVal));
}
}
public static void main(String[] args) {
SAXParserTest spe = new SAXParserTest();
spe.runExample();
}
}
Content of employees.xml document for parsing
<?xml version="1.0" encoding="UTF-8"?>
<Personnel>
<Employee type="permanent">
<Name>John</Name>
<Id>1000</Id>
<Age>34</Age>
</Employee>
<Employee type="contract">
<Name>Robin</Name>
<Id>1001</Id>
<Age>25</Age>
</Employee>
<Employee type="permanent">
<Name>Neil</Name>
<Id>1002</Id>
<Age>26</Age>
</Employee>
</Personnel>
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