dom by kamalakar dandu

8/2/2019 Dom by Kamalakar Dandu

1/30

The Document Object Model (DOM) APIs


2/30

Why DOM

ensures proper grammar and well-formedness.

The DOM abstracts content away fromgrammer.

simplifies internal document manipulation.

Mirrors typical hierarchical and relationaldatabase structures


3/30

A Simple XML Structure


5/30

The DOM specification

DOM specification is maintained by theW3C.

DOM Level 1

contains two main sections

1. DOM core level 1.

(Interfaces that can assess any

structured document)2. HTML specific extensions to theDOM.


6/30

DOM Level 2

Specification currently has the status ofcandidate Recommendation this meansthat it has received significant review from

its immediate technical community, andnow requires implementation and technical

feedback from parties external to the

W3C.


7/30

DOM Level 2 (contd)

support for namespaces

Style sheets - includs boject model for stylesheets & methods to Query and manipulate the

style-sheet. Filters - DOM level 2 adds methods for

filtering the Documents.

Event model - event model for XML is planned

for level 2 DOM Ranges - the level 2 DOM includes functions

for manipulation large blocks of text.


8/30

Java API for DOM

DocumentBuilderFactory : Defines afactory API that enables applications toobtain a parser that produces DOM object

trees from XML documents. (not Threadsafe)

DocumentBuilder : Defines the API to

obtain DOM Document instances from anXML document.


9/30

Important Methods InDocumentBuilderFactory

Public DocumentBuilder newDocumentBuilder()

Public static DocumentBuilderFactory newInstance()

Public void is/setExpandEntityReferences (boolean)

Public void is/setIgnoringComments(boolean)Public void is/setIgnoringElementContentWhitespace(boolean)

Public void is/setNamespaceAware(boolean)

Public void is/setValidating(boolean)


10/30

Important Methods InDocumentBuilder

Public boolean isNamespaceAware()

Public boolean isValidating()

Public Document newDocument()

Public Document parse(File f) Public Document parse(InputSource f)

Public Document parse(InputStream f)

Public void setEntityResolver(EntityResolver er)Public void setErrorHandler(ErrorHandler eh)


11/30

Important Interfaces Inorg.w3c.dom Package

Attr

CharacterData

Comment

Document

DocumentFragment

DocumentType

Element

EntityEntityReference

Notation

ProcessingInstruction

Text


12/30

Important Methods InNode Interface

Node appendChild(Node newChild)

Node cloneNode(boolean deep)

NamedNodeMap getAttributes()

NodeList getChildNodes()

Node getFirstChild()

Node getLastChild()

String getNamespaceURI()

Node getNextSibling()


13/30

Important Methods InNode Interface (contd)

String getNodeName()

short getNodeType()

String getNodeValue()

Document getOwnerDocument() Node getParentNode()

String getPrefix()

Node getPreviousSibling() boolean hasAttributes()

boolean hasChildNodes()


14/30

Important Methods InNode Interface (contd)

boolean hasChildNodes()

Node insertBefore(Node newChild, Node refChild)

void normalize()

Node removeChild(Node oldChild)

Node replaceChild(Node newChild, NodeoldChild)

void setNodeValue(String nodeValue)

void setPrefix(String prefix)


15/30

Create the Skeleton

Start with a normal basic logic:

public class DomEcho {

public static void main(String argv[]) {

if (argv.length != 1) {

System.err.println("Usage: java DomEcho filename");

System.exit(1);

}

}// main

}// DomEcho


16/30

Create the Skeleton (Contd..)

Import the Required Classes:import javax.xml.parsers.DocumentBuilder;import javax.xml.parsers.DocumentBuilderFactory;import javax.xml.parsers.FactoryConfigurationError;

import javax.xml.parsers.ParserConfigurationException;

import org.xml.sax.SAXException;import org.xml.sax.SAXParseException;

import java.io.File;import java.io.IOException;

import org.w3c.dom.Document;import org.w3c.dom.DOMException;


17/30


Declare the DOM

public class DomEcho {

static Document document;

public static void main (String[] args) {

.


18/30

try {

} catch (SAXParseException spe) {// Error generated by the parserSystem.out.println("\n** Parsing error" + ", line " +

spe.getLineNumber() + ", uri " + spe.getSystemId());System.out.println(" " + spe.getMessage() );

// Use the contained exception, if any

Exception x = spe;if (spe.getException() != null)

x = spe.getException();x.printStackTrace();

}



19/30

Instantiate the Factory

public static void main(String argv[]) {if (argv.length != 1) {...

}DocumentBuilderFactory factory

=DocumentBuilderFactory.newInstance();

try {


20/30

Get a Parser and Parse the File

try {

DocumentBuilder builder = factory.newDocumentBuilder();

document = builder.parse( new File(argv[0]) );

} catch (SAXParseException spe) {


21/30

Create the SkeletonExample

Example :

XML : slideSample01.xml

Java : DomEcho01.java


22/30

Creating an XML DOM Document

Create a Document Object :

DocumentBuilderFactory documentBuilderFactory =DocumentBuilderFactory.newInstance();

documentBuilderFactory.setValidating(false);documentBuilderFactory.setNamespaceAware(false);

DocumentBuilder builder =

documentBuilderFactory.newDocumentBuilder();

Document document = builder.newDocument();


23/30

Creating an XML DOM Document(contd)

A method to create an Element :

private Element createElement(Document doc,Nodeparent,String name, String value) {

Element elem=doc.createElement(name);

if(value!=null){Text text=doc.createTextNode(value);elem.appendChild(text);

}

parent.appendChild(elem);return elem;

}


24/30

Creating an XML DOM Document

(contd)

A method to create an Element :

private Attr createAttribute(Document doc, Elementelement, String attrName, String attrValue) {

Attr attr = null;

if(attrName != null)attr =doc.createAttribute(attrName);

if(attrValue!=null)attr.setValue(attrValue);

if(element != null && attr!=null)element.setAttributeNode(attr);

return attr;

}Example :CreateEmpXML.java


25/30

Exercise

Product.xml stores below information

Product Name Price Quantity

Monitor 10000 5

keyBoard 1000 3

CPU 12000 6

Write the below programs :

1. Add a new product to the list

2. Update the product price and quantity

Reference : DOMReaderDemo.java, ProductDemo.java

Note : The Changes made to the Product XML need not berecorded. You are only required to store the changes in DOM treeand display the same.


26/30

Validating with XML Schema

Overview of the Validation Process

To be notified of validation errors in anXML document,

The factory must configured, andthe appropriate error handler set.

The document must be associated withat least one schema, and possiblymore.


27/30

Configuring the DocumentBuilderFactory

static final String JAXP_SCHEMA_LANGUAGE= "http://java.sun.com/xml/jaxp/properties/schemaLanguage";

static final String W3C_XML_SCHEMA= "http://www.w3.org/2001/XMLSchema";

DocumentBuilderFactory factory= DocumentBuilderFactory.newInstance();factory.setNamespaceAware(true);

factory.setValidating(true);try {factory.setAttribute(JAXP_SCHEMA_LANGUAGE,W3C_XML_SCHEMA);} catch (IllegalArgumentException x) {

// Happens if the parser does not support JAXP 1.2}


28/30

Associating a Document with aSchema

There are two ways to do that:

1. With a schema declaration in theXML document.

2. By specifying the schema(s) touse in the application.


29/30

To specify the schema definition in

the document, you would create

XML like this:

...

S f f


30/30

Specifying the schema file in the

application

static final String schemaSource ="YourSchemaDefinition.xsd";

static final String JAXP_SCHEMA_SOURCE =

"http://java.sun.com/xml/jaxp/properties/schemaSource";

...DocumentBuilderFactory factory =

DocumentBuilderFactory.newInstance()

...

factory.setAttribute(JAXP_SCHEMA_SOURCE,new File(schemaSource));

Example :Java File : ValidateSchema.java

XML : Greeting xml XSD : Greeting xsd