1 / 19

3.3 JAXP: Java API for XML Processing

3.3 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?

blake
Download Presentation

3.3 JAXP: Java API for XML Processing

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. 3.3 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] Notes 3: XML Processor Interfaces

  2. JAXP 1.1 • An interface for “plugging-in” and using XML processors in Java applications • includes packages • org.xml.sax: SAX 2.0 interface • 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 Notes 3: XML Processor Interfaces

  3. JAXP: XML processor plugin (1) • Vendor-independent method for selecting processor implementation at run time • principally through system propertiesjavax.xml.parsers.SAXParserFactory,javax.xml.parsers.DocumentBuilderFactory, andjavax.xml.transform.TransformerFactory • For example:System.setProperty("javax.xml.parsers.DocumentBuilderFactory", "com.icl.saxon.om.DocumentBuilderFactoryImpl"); Notes 3: XML Processor Interfaces

  4. 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 Notes 3: XML Processor Interfaces

  5. JAXP: Functionality • Parsing using SAX 2.0 or DOM Level 2 • Transformation using XSLT • (We’ll perform stand-alone transformations later) • Fixes features left unspecified in SAX 2.0 and DOM Level 2 • control of parser validation and error handling • creation and saving of DOM Document objects Notes 3: XML Processor Interfaces

  6. JAXP Parsing API • Included in JAXP package javax.xml.parsers • Used for invoking and using SAX and DOM parser implementations:SAXParserFactory spf =SAXParserFactory.newInstance();DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); Notes 3: XML Processor Interfaces

  7. getXMLReader XML JAXP: Using an SAX parser (1) Notes 3: XML Processor Interfaces

  8. JAXP: Using an SAX parser (2) • We’ve already used this: SAXParserFactory spf =SAXParserFactory.newInstance(); try { SAXParser saxParser = spf.newSAXParser(); XMLReader xmlReader = saxParser.getXMLReader(); } catch (Exception e) { System.err.println(e.getMessage()); System.exit(1); }; Notes 3: XML Processor Interfaces

  9. parse( ”f.xml”) newDocument() f.xml JAXP: Using a DOM parser (1) Notes 3: XML Processor Interfaces

  10. JAXP: Using a DOM parser (2) • We’ve used this, too: DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); try {// to get a newDocumentBuilder:documentBuilder builder = dbf.newDocumentBuilder(); } catch (ParserConfigurationException e) { e.printStackTrace()); System.exit(1); }; Notes 3: XML Processor Interfaces

  11. XML DOM building in JAXP Document Builder (Content Handler) XML Reader Error Handler DOM Document (SAX Parser) DTD Handler Entity Resolver DOM on top of SAX - So what? Notes 3: XML Processor Interfaces

  12. Validation and namespace processing can be controlled, both for SAXParserFactories and DocumentBuilderFactories with setValidating(boolean)and setNamespaceAware(boolean) JAXP: Controlling parsing • Errors of DOM parsing can be handled • by creating a SAXErrorHandler, which implements error, fatalError and warning methods, and passing it with setErrorHandler to the DocumentBuilder Notes 3: XML Processor Interfaces

  13. 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) Notes 3: XML Processor Interfaces

  14. JAXP: Using Transformers (1) XSLT Notes 3: XML Processor Interfaces

  15. 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, an SAX XMLReader or an I/O stream • Transformation Result object can be • a DOM tree, an SAX ContentHandler or an I/O stream Notes 3: XML Processor Interfaces

  16. JAXP Transformation Packages (2) • Classes to create Source and Result objects from DOM, SAX and I/O streams defined in packages • javax.xml.transform.dom,javax.xml.transform.sax,andjavax.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) Notes 3: XML Processor Interfaces

  17. Serializing a DOM Document as XML text • Identity transformation to an I/O stream Result: TransformerFactory tFactory =TransformerFactory.newInstance(); // Create an identity transformer:Transformer transformer = tFactory.newTransformer();DOMSource source = new DOMSource(myDOMdoc);StreamResult result = new StreamResult(System.out);transformer.transform(source, result); Notes 3: XML Processor Interfaces

  18. 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/ Notes 3: XML Processor Interfaces

  19. JAXP: Summary • An interface for using XML Processors • SAX/DOM parsers, XSLT transformers • Supports plugability of different implementations • Defines means to control validation, and handling of parse errors (through SAX ErrorHandlers) • Defines means to write out DOM Documents • Included in JDK 1.4 Notes 3: XML Processor Interfaces

More Related