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JAXP

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Course Schedule

Day 1 of 1

Understand the need of JAXP

XML processors

JAXP Functionality

Parsing using DOM

JAXP Transformers

Demo exercises

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Course Objectives

Understand the need of JAXP

Understand the XML processors

Understand the JAXP Functionality

Learn parsing using DOM and JAXP Transformers

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JAXP: Java API for XML Processing

How can applications use XML processors?

A Java-based answer: through JAXP

An overview of the JAXP interface

What does it specify?What can be done with it?

How do the JAXP components fit together?

[Partly based on tutorial An Overview of the APIs available at

http://java.sun.com/xml/jaxp/dist/1.1/docs/tutorial/overview/3_apis.html, from which also

some graphics are borrowed]

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JAXP 1.1

An interface for plugging-in and using XML

processors in Java applications

includes packages

org.w3c.dom: DOM Level 2 interface

javax.xml.parsers:

initialization and use of parsers

javax.xml.transform:

initialization and use of transformers

(XSLT processors)

Included in JDK starting from vers. 1.4

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JAXP: XML processor plugin (1)

Vendor-independent method for selecting processor

implementation at run time

principally through system properties

javax.xml.parsers.DocumentBuilderFactory, and

javax.xml.transform.TransformerFactory

For example:

System.setProperty(

"javax.xml.parsers.DocumentBuilderFactory",

"com.icl.saxon.om.DocumentBuilderFactoryImpl");

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JAXP: XML processor plugin (2)

By default, reference implementations used

Apache Crimson/Xerces as the XML parser

Apache Xalan as the XSLT processor

Currently supported only by a few compliant XML processors:

Parsers: Apache Crimson and Xerces, Aelfred

XSLT transformers: Apache Xalan, Saxon

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JAXP: Functionality

Parsing using DOM Level 2

Transformation using XSLT

(Well perform stand-alone transformations later)

Fixes features left unspecified in DOM Level 2

control of parser validation and error handling

creation and saving of DOM Document objects

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JAXP Parsing API

Included in JAXP package

javax.xml.parsers

Used for invoking and using DOM parser implementations:

DocumentBuilderFactorydbf =

DocumentBuilderFactory.newInstance();

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f.f.xmlxml

parseparse((

f.f.xmlxml)) newDocumentnewDocument()()

JAXP: Using a DOM parser (1)

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JAXP: Using a DOM parser (2)

Weve used this, too:

DocumentBuilderFactoryDocumentBuilderFactorydbf =dbf =

DocumentBuilderFactoryDocumentBuilderFactory..newInstancenewInstance();();

try {try {// to get a new// to get a newDocumentBuilderDocumentBuilder::

documentBuilderdocumentBuilderbuilder =builder =

dbf.dbf.newDocumentBuildernewDocumentBuilder();();

} catch (} catch (ParserConfigurationExceptionParserConfigurationExceptione) {e) {

e.printStackTracee.printStackTrace());());

System.exit(1);System.exit(1);

};};

TestDOMParsing.javaTestDOMParsing.java

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DOM building in JAXP

XMLXML

ReaderReader

(SAX(SAX

ParserParser))

XMLXML

ErrorErrorHandlerHandler

DTDDTDHandlerHandler

EntityEntityResolverResolver

DocumentDocumentBuilderBuilder

((ContentContent

HandlerHandler))

DOMDOM DocumentDocument

DOM on top of SAXDOM on top of SAX -- So whatSo what??

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JAXP: Controlling parsing

Errors of DOM parsing can be handled

by creating a ErrorHandler, which implements error, fatalError and

warning methods, and passing it with setErrorHandler to theDocumentBuilder

setValidatingsetValidating(boolean(boolean)) andandsetNamespaceAwaresetNamespaceAware(boolean(boolean))

Validation and namespace processing can be controlled for

DocumentBuilderFactories with

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JAXP Transformation API

also known as TrAX

Allows application to apply a Transformer to a Source document to get

a Result document

Transformer can be created

from XSLT transformation instructions (to be discussed later)

without instructions, which gives an identity transformation (simply copies

Source to Result)

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XSLTXSLT

JAXP: Using Transformers (1)

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JAXP Transformation Packages

javax.xml.transform:

Classes Transformer and TransformerFactory; initialization

similar to parsers and parser factories

Transformation Source object can be a DOM tree or an I/O stream

Transformation Result object can be

a DOM tree or an I/O stream

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JAXP Transformation Packages (2)

Classes to create Source and Result objects from DOM and I/O

streams defined in packages

javax.xml.transform.dom, and

javax.xml.transform.stream

An identity transformation from a DOM Document to I/O stream

a vendor-neutral way to serialize DOM documents

(the only option in JAXP)

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Serializing a DOM Document as XML text

Identity transformation to an I/O stream Result:

TransformerFactoryTransformerFactorytFactorytFactory==

TransformerFactoryTransformerFactory..newInstancenewInstance();();//// CreateCreate anan identity transformeridentity transformer::

TransformerTransformertransformertransformer==

tFactorytFactory..newTransformernewTransformer();();

DOMSourceDOMSourcesourcesource= new= newDOMSourceDOMSource((myDOMdocmyDOMdoc););

StreamResultStreamResultresultresult==

newnew StreamResultStreamResult((SystemSystem.out);.out);

transformertransformer..transformtransform((sourcesource,,resultresult););

Transform.javaTransform.java

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Other Java APIs for XML

JDOM

variant of W3C DOM; closer to Java object-orientation

(http://www.jdom.org/)

DOM4J (http://www.dom4j.org/)

roughly similar to JDOM; richer set of features

JAXB (Java Architecture for XML Binding)

compiles DTDs to DTD-specific classes that allow to read, to

manipulate and to write valid documents

http://java.sun.com/xml/jaxb/

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JAXP: Summary

An interface for using XML Processors

DOM parsers, XSLT transformers

Supports plugability of different implementations Defines means to control validation, and handling of parse errors

Defines means to write out DOM Documents

Included in JDK 1.4

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Thank You