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JSR 172: XML Parsing in MIDP


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JSR 172: XML Parsing in MIDP

  1. 1. JAXP Parsing in Java ME
  2. 2. JSR 172 <ul><li>JSR 172: Java ME Web Services </li></ul><ul><ul><li>Access to remote SOAP / XML Based web services </li></ul></ul><ul><ul><li>Parsing XML data </li></ul></ul>
  3. 3. JAXP Java ME Edition <ul><li>JSR 172 is a subset of JSR 063 </li></ul><ul><ul><li>JSR 63: Java API for XML Processing </li></ul></ul><ul><ul><li> </li></ul></ul><ul><li>Requires only CLDC 1.0 </li></ul><ul><li>Basic XML Parsing capabilities </li></ul>
  4. 4. API Features and Restrictions <ul><li>SAX 2.0 subset </li></ul><ul><li>XML Namespaces </li></ul><ul><li>UTF-8 and UTF-16 support </li></ul><ul><li>May support validation (DTD) </li></ul><ul><li>No DOM – handling </li></ul><ul><ul><li>Too heavy, size and runtime memory </li></ul></ul><ul><li>No XSLT Transformations </li></ul>
  5. 5. Packages <ul><li>javax.xml.parsers </li></ul><ul><ul><li>To obtain and reference platform's parser </li></ul></ul><ul><ul><ul><li>SAXParser, SAXParserFactory... </li></ul></ul></ul><ul><li>org.xml.sax </li></ul><ul><ul><li>Subset of SAX 2.0 API Classes and interfaces. </li></ul></ul><ul><ul><ul><li>Attributes, Locator, InputSource, SAX??Exceptions </li></ul></ul></ul><ul><li>org.xml.sax.helpers </li></ul><ul><ul><li>Class to extend to receive parse events </li></ul></ul><ul><ul><ul><li>DefaultHandler </li></ul></ul></ul>
  6. 6. Basic Idea behind SAX <ul><li>SAX = Simple API for XML </li></ul><ul><ul><li>See </li></ul></ul><ul><li>Event driven way of handling xml-data </li></ul><ul><li>Only reading (no manipulation of the xml – data) </li></ul>
  7. 7. Creating Parser <ul><li>SAXParserFactory factory = SAXParserFactory.newInstance(); </li></ul><ul><li>SAXParser saxParser = factory.newSAXParser(); </li></ul><ul><li>saxParser. parse (..., ...); </li></ul>
  8. 8. SAXParser parse <ul><li>parse(org.xml.sax.InputSource is, DefaultHandler dh); </li></ul><ul><li>parse( is, DefaultHandler dh); </li></ul>
  9. 9. Default Handler? <ul><li>Create your own handler by inheriting the Default Handler </li></ul><ul><ul><li>Class MyHandler extends DefaultHandler { </li></ul></ul><ul><ul><li>} </li></ul></ul><ul><li>Override methods you want </li></ul>
  10. 10. Example <ul><li>public class MyXMLParser extends DefaultHandler { </li></ul><ul><li>public void startDocument () throws SAXException { } </li></ul><ul><li>public void startElement (String uri, String localName, String qName, Attributes attributes) throws SAXException { } </li></ul><ul><li>public void characters (char[] ch, int start, int length) throws SAXException { } </li></ul><ul><li>public void endElement (String uri, String localName, String qName) throws SAXException { } </li></ul><ul><li>public void endDocument () throws SAXException { } </li></ul><ul><li>} </li></ul>
  11. 11. Creating Parser <ul><li>SAXParserFactory factory = SAXParserFactory.newInstance(); </li></ul><ul><li>SAXParser saxParser = factory.newSAXParser(); </li></ul><ul><li>String xml = &quot;<root><child>content</child></root>&quot;; </li></ul><ul><li>ByteArrayInputStream s = new ByteArrayInputStream(xml.getBytes()); </li></ul><ul><li>saxParser. parse (s, new MyXMLParser()); </li></ul>