Reading XML file inwards coffee using SAX Parser is lilliputian unlike than reading xml file inwards Java alongside DOM parser which nosotros had discussed inwards final article of this series. This tutorial is tin flaming live on useful for those who are novel to the coffee Blue Planet in addition to got the requirement for read an xml file inwards java inwards their projection or assignment, primal characteristic of coffee is it provides built inwards cast in addition to object to grip everything which makes our work really easy. Basically this procedure of treatment XML file is known every bit parsing agency suspension downwards the whole string into small-scale pieces using the exceptional tokens.
Parsing tin flaming live on done using 2 ways:
- Using DOM Parser
- Using SAX Parser
Read XML file inwards Java Using SAX Parser Example
In DOM parser nosotros receive got seen that nosotros receive got to follow unproblematic 3 steps:
Ø Parse the XML file
Ø Create the coffee object
Ø Manipulate the object agency nosotros tin flaming read that object or add together them to listing or any component subdivision nosotros desire nosotros tin flaming do
But inwards SAX Parser its lilliputian fleck different.
SAX Parser: it’s an resultant based parsing it contains default handler for treatment the events whenever SAX parser pareses the xml document in addition to it finds the Start tag “<” in addition to halt tag”>” it calls corresponding handler method. Though at that topographic point are other ways too to larn information from xml file e.g. using XPATH inwards Java which is a linguistic communication similar SQL in addition to give selective information from xml file.
Sample Example of reading XML File – SAX Parser
Suppose nosotros receive got this sample XML file bank.xml which contains occupation organisation human relationship details of all accounts inwards a hypothetical bank:
<?xml version="1.0" encoding="UTF-8"?>
<Bank>
<Account type="saving">
<Id>1001</Id>
<Name>Jack Robinson</Name>
<Amt>10000</Amt>
</Account>
<Account type="current">
<Id>1002</Id>
<Name>Sony Corporation</Name>
<Amt>1000000</Amt>
</Account>
</Bank>
1. Create the SAX parser in addition to parse the XML file: In this measuring nosotros volition receive got i mill illustration from SAXParserFactory to parse the xml file this mill illustration inwards turns give us illustration of parser using the parse() method volition parse the Xml file.
2. Event Handling: when Sax Parser starts the parsing whenever it founds the start or halt tag it volition invoke the corresponding resultant treatment method which is public void startElement (…) in addition to world void halt Element (...).
3. Register the events: The cast extends the Default Handler cast to nous for callback events in addition to nosotros register this handler to sax Parser to notify us for telephone telephone dorsum event
Let see coffee code for all these steps
To stand upwards for information from our sample xml file nosotros involve i coffee domain object called Account:
package parser;
public class Account {
private String name;
private int id;
private int amt;
private String type;
public Account() {
}
public Account(String name, int id, int amt, String type) {
this.name = name;
this.amt = amt;
this.id = id;
this.type = type;
}
public int getAmt() {
return amt;
}
public void setAmt(int amt) {
this.amt = amt;
}
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("Account Details - ");
sb.append("Name:" + getName());
sb.append(", ");
sb.append("Type:" + getType());
sb.append(", ");
sb.append("Id:" + getId());
sb.append(", ");
sb.append("Age:" + getAmt());
sb.append(".");
return sb.toString();
}
}
Sample Code for implementing SAX parser inwards Java
package parser;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Iterator;
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 ReadXMLFileUsingSaxparser extends DefaultHandler {
private Account acct;
private String temp;
private ArrayList<Account> accList = new ArrayList<Account>();
/** The principal method sets things upwards for parsing */
public static void main(String[] args) throws IOException, SAXException,
ParserConfigurationException {
//Create a "parser factory" for creating SAX parsers
SAXParserFactory spfac = SAXParserFactory.newInstance();
//Now purpose the parser mill to create a SAXParser object
SAXParser sp = spfac.newSAXParser();
//Create an illustration of this class; it defines all the handler methods
ReadXMLFileUsingSaxparser handler = new ReadXMLFileUsingSaxparser();
//Finally, nation the parser to parse the input in addition to notify the handler
sp.parse("bank.xml", handler);
handler.readList();
}
/*
* When the parser encounters manifestly text (not XML elements),
* it calls(this method, which accumulates them inwards a string buffer
*/
public void characters(char[] buffer, int start, int length) {
temp = new String(buffer, start, length);
}
/*
* Every fourth dimension the parser encounters the maiden of all of a novel element,
* it calls this method, which resets the string buffer
*/
public void startElement(String uri, String localName,
String qName, Attributes attributes) throws SAXException {
temp = "";
if (qName.equalsIgnoreCase("Account")) {
acct = new Account();
acct.setType(attributes.getValue("type"));
}
}
/*
* When the parser encounters the halt of an element, it calls this method
*/
public void endElement(String uri, String localName, String qName)
throws SAXException {
if (qName.equalsIgnoreCase("Account")) {
// add together it to the list
accList.add(acct);
} else if (qName.equalsIgnoreCase("Name")) {
acct.setName(temp);
} else if (qName.equalsIgnoreCase("Id")) {
acct.setId(Integer.parseInt(temp));
} else if (qName.equalsIgnoreCase("Amt")) {
acct.setAmt(Integer.parseInt(temp));
}
}
private void readList() {
System.out.println("No of the accounts inwards banking concern '" + accList.size() + "'.");
Iterator<Account> it = accList.iterator();
while (it.hasNext()) {
System.out.println(it.next().toString());
}
}
}
Output:
No of the accounts inwards banking concern '2'.
Account Details - Name:Jack Robinson, Type:saving, Id:1001, Age:10000.
Account Details - Name:Sony Corporation, Type:current, Id:1002, Age:1000000.
Output:
No of the accounts inwards banking concern '2'.
Account Details - Name:Jack Robinson, Type:saving, Id:1001, Age:10000.
Account Details - Name:Sony Corporation, Type:current, Id:1002, Age:1000000.
Advantage of SAX parser inwards Java:
It is faster than DOM parser because it volition non charge the XML document into the retentivity .its an resultant based.
Further Reading
Java Fundamentals: The Java Language
XML Fundamentals
RESTFul Services inwards Java using Jersey
Core Java, Volume II--Advanced Features
XSLT 2.0 in addition to 1.0 Foundations
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