17 Apr 2002

XML Programming: TrAX

Andy Clark

Java API for XML Processing

Standard Java API for loading, creating, accessing, and transforming XML documents– JAXP: parsing

Supports DOM and SAX

– TrAX: transformation Generic transformation framework

Java standard extension (i.e. javax package)– Defined by Sun JCP

Transformation API for XML

Transformation framework– Allows generic transformation from one form to

another

Examples:– Serializers– XSLT processors– etc…

javax.xml.transform (1 of 2)

Transformation– Transformer, TransformerFactory– Templates

Input and Output– Source– Result

javax.xml.transform (2 of 2)

Transformer control– ErrorListener– SourceLocator, URIResolver– OutputKeys

Other– TransformerConfigurationException– TransformerException– TransformerFactoryConfigurationError

Input and Output

javax.xml.transform.stream– StreamSource– StreamResult

javax.xml.transform.dom– DOMSource, DOMResult– DOMLocator

javax.xml.transform.sax– SAXSource, SAXResult– SAXTransformerFactory– TransformerHandler, TemplatesHandler

Stream Input and Output

StreamSource– Specifies document stream to parse

StreamResult– Specifies stream for serialization of document– OutputKeys controls serialization settings

DOM/SAX Input and Output

Document Object Model– DOMSource

Specifies document or node to process

– DOMResult Specifies document factory for new nodes

Simple API for XML– SAXSource

Specifies XMLReader to parse document

– SAXResult Specifies handler for generated events

Transform Document (1 of 3)

Identity transform– Get instance of transformer factory

TransformerFactory factory = TransformerFactory.newInstance();

– Create transformer Transformer transformer = factory.newTransformer();

– Create input and output Source source = new StreamSource(“document.xml”); Result result = new StreamResult(System.out);

– Transform document transformer.transform(source, result);

Transform Document (2 of 3)

Transform with stylesheet (1 of 2)– Get instance of transformer factory

TransformerFactory factory = TransformerFactory.newInstance();

– Create templates Source templatesSource = new StreamSource(“style.xsl”); Templates templates = factory.newTemplates(templatesSour

ce);

– Create transformer Transformer transformer = templates.newTransformer();

Transform Document (3 of 3)

Transform with Stylesheet (2 of 2)– Create input and output

Source source = new StreamSource(“document.xml”); Result result = new StreamResult(System.out);

– Transform document transformer.transform(source, result);

Error Handling and Entity Resolution

Transformer– Can set a TrAX ErrorListener– Can set a TrAX URIResolver

URIResolver– Called when reference to multiple documents

Passed base and literal system identifiers of resource Example XPath: “document(‘book.xml’)/book/title”

– Returns a TrAX Source Note: This is super cool because it means that you can

cache (or generate) documents in memory.

Useful Links

JAXP– http://java.sun.com/xml/

Apache Xalan XSLT Processor– http://xml.apache.org/xalan-j/

XML Programming: TrAX

Andy Clark