jdomresult.java

JAVA的Jdom包

   * This is needed to handle XML comments and the like.  If the
   * lexical handler is not set, an attempt should be made by the
   * transformer to cast the ContentHandler to a LexicalHandler.</p>
   *
   * @param handler A non-null LexicalHandler for
   *                handling lexical parse events.
   */
  public void setLexicalHandler(LexicalHandler handler) { }


  //=========================================================================
  // FragmentHandler nested class
  //=========================================================================

  private static class FragmentHandler extends SAXHandler {
    /**
     * A dummy root element required by SAXHandler that can only
     * cope with well-formed documents.
     */
    private Element dummyRoot = new Element("root", null, null);

    /**
     * Public constructor.
     */
    public FragmentHandler(JDOMFactory factory) {
      super(factory);

      // Add a dummy root element to the being-built document as XSL
      // transformation can output node lists instead of well-formed
      // documents.
      this.pushElement(dummyRoot);
    }

    /**
     * Returns the result of an XSL Transformation.
     *
     * @return the transformation result as a (possibly empty) list of
     *         JDOM nodes (Elements, Texts, Comments, PIs...).
     */
    public List getResult() {
      // Flush remaining text content in case the last text segment is
      // outside an element.
      try {
        this.flushCharacters();
      }
      catch (SAXException e) { /* Ignore... */  }
      return this.getDetachedContent(dummyRoot);
    }

    /**
     * Returns the content of a JDOM Element detached from it.
     *
     * @param  elt   the element to get the content from.
     *
     * @return a (possibly empty) list of JDOM nodes, detached from
     *         their parent.
     */
    private List getDetachedContent(Element elt) {
      List content = elt.getContent();
      List nodes   = new ArrayList(content.size());

      while (content.size() != 0)
      {
        Object o = content.remove(0);
        nodes.add(o);
      }
      return (nodes);
    }
  }

  //=========================================================================
  // DocumentBuilder inner class
  //=========================================================================

  private class DocumentBuilder extends XMLFilterImpl
                                implements LexicalHandler {
    /**
     * The actual JDOM document builder.
     */
    private FragmentHandler saxHandler = null;

    /**
     * Whether the startDocument event was received. Some XSLT
     * processors such as Oracle's do not fire this event.
     */
    private boolean startDocumentReceived = false;

    /**
     * Public default constructor.
     */
    public DocumentBuilder() { }

    /**
     * Returns the result of an XSL Transformation.
     *
     * @return the transformation result as a (possibly empty) list of
     *         JDOM nodes (Elements, Texts, Comments, PIs...) or
     *         <code>null</code> if no new transformation occurred
     *         since the result of the previous one was returned.
     */
    public List getResult() {
      List result = null;

      if (this.saxHandler != null) {
        // Retrieve result from SAX content handler.
        result = this.saxHandler.getResult();

        // Detach the (non-reusable) SAXHandler instance.
        this.saxHandler = null;

        // And get ready for the next transformation.
        this.startDocumentReceived = false;
      }
      return result;
    }

    private void ensureInitialization() throws SAXException {
      // Trigger document initialization if XSLT processor failed to
      // fire the startDocument event.
      if (this.startDocumentReceived == false) {
        this.startDocument();
      }
    }

    //-----------------------------------------------------------------------
    // XMLFilterImpl overwritten methods
    //-----------------------------------------------------------------------

    /**
     * <i>[SAX ContentHandler interface support]</i> Processes a
     * start of document event.
     * <p>
     * This implementation creates a new JDOM document builder and
     * marks the current result as "under construction".</p>
     *
     * @throws SAXException   if any error occurred while creating
     *                        the document builder.
     */
    public void startDocument() throws SAXException {
      this.startDocumentReceived = true;

      // Reset any previously set result.
      setResult(null);

      // Create the actual JDOM document builder and register it as
      // ContentHandler on the superclass (XMLFilterImpl): this
      // implementation will take care of propagating the LexicalHandler
      // events.
      this.saxHandler = new FragmentHandler(getFactory());
      super.setContentHandler(this.saxHandler);

      // And propagate event.
      super.startDocument();
    }

    /**
     * <i>[SAX ContentHandler interface support]</i> Receives
     * notification of the beginning of an element.
     * <p>
     * This implementation ensures that startDocument() has been
     * called prior processing an element.
     *
     * @param  nsURI       the Namespace URI, or the empty string if
     *                     the element has no Namespace URI or if
     *                     Namespace processing is not being performed.
     * @param  localName   the local name (without prefix), or the
     *                     empty string if Namespace processing is
     *                     not being performed.
     * @param  qName       the qualified name (with prefix), or the
     *                     empty string if qualified names are not
     *                     available.
     * @param  atts        The attributes attached to the element.  If
     *                     there are no attributes, it shall be an
     *                     empty Attributes object.
     *
     * @throws SAXException   if any error occurred while creating
     *                        the document builder.
     */
    public void startElement(String nsURI, String localName, String qName,
                                           Attributes atts) throws SAXException
    {
      this.ensureInitialization();
      super.startElement(nsURI, localName, qName, atts);
    }

    /**
     * <i>[SAX ContentHandler interface support]</i> Begins the
     * scope of a prefix-URI Namespace mapping.
     */
    public void startPrefixMapping(String prefix, String uri)
                                                        throws SAXException {
      this.ensureInitialization();
      super.startPrefixMapping(prefix, uri);
    }

    /**
     * <i>[SAX ContentHandler interface support]</i> Receives
     * notification of character data.
     */
    public void characters(char ch[], int start, int length)
                                                        throws SAXException {
      this.ensureInitialization();
      super.characters(ch, start, length);
    }

    /**
     * <i>[SAX ContentHandler interface support]</i> Receives
     * notification of ignorable whitespace in element content.
     */
    public void ignorableWhitespace(char ch[], int start, int length)
                                                        throws SAXException {
      this.ensureInitialization();
      super.ignorableWhitespace(ch, start, length);
    }

    /**
     * <i>[SAX ContentHandler interface support]</i> Receives
     * notification of a processing instruction.
     */
    public void processingInstruction(String target, String data)
                                                        throws SAXException {
      this.ensureInitialization();
      super.processingInstruction(target, data);
    }

    /**
     * <i>[SAX ContentHandler interface support]</i> Receives
     * notification of a skipped entity.
     */
    public void skippedEntity(String name) throws SAXException {
      this.ensureInitialization();
      super.skippedEntity(name);
    }

    //-----------------------------------------------------------------------
    // LexicalHandler interface support
    //-----------------------------------------------------------------------

    /**
     * <i>[SAX LexicalHandler interface support]</i> Reports the
     * start of DTD declarations, if any.
     *
     * @param  name       the document type name.
     * @param  publicId   the declared public identifier for the
     *                    external DTD subset, or <code>null</code>
     *                    if none was declared.
     * @param  systemId   the declared system identifier for the
     *                    external DTD subset, or <code>null</code>
     *                    if none was declared.
     *
     * @throws SAXException   The application may raise an exception.
     */
    public void startDTD(String name, String publicId, String systemId)
                                        throws SAXException {
      this.ensureInitialization();
      this.saxHandler.startDTD(name, publicId, systemId);
    }

    /**
     * <i>[SAX LexicalHandler interface support]</i> Reports the end
     * of DTD declarations.
     *
     * @throws SAXException   The application may raise an exception.
     */
    public void endDTD() throws SAXException {
      this.saxHandler.endDTD();
    }

    /**
     * <i>[SAX LexicalHandler interface support]</i> Reports the
     * beginning of some internal and external XML entities.
     *
     * @param  name   the name of the entity.  If it is a parameter
     *                entity, the name will begin with '%', and if it
     *                is the external DTD subset, it will be "[dtd]".
     *
     * @throws SAXException   The application may raise an exception.
     */
    public void startEntity(String name) throws SAXException {
      this.ensureInitialization();
      this.saxHandler.startEntity(name);
    }

    /**
     * <i>[SAX LexicalHandler interface support]</i> Reports the end
     * of an entity.
     *
     * @param  name   the name of the entity that is ending.
     *
     * @throws SAXException   The application may raise an exception.
     */
    public void endEntity(String name) throws SAXException {
      this.saxHandler.endEntity(name);
    }

    /**
     * <i>[SAX LexicalHandler interface support]</i> Reports the
     * start of a CDATA section.
     *
     * @throws SAXException   The application may raise an exception.
     */
    public void startCDATA() throws SAXException {
      this.ensureInitialization();
      this.saxHandler.startCDATA();
    }

    /**
     * <i>[SAX LexicalHandler interface support]</i> Reports the end
     * of a CDATA section.
     *
     * @throws SAXException   The application may raise an exception.
     */
    public void endCDATA() throws SAXException {
      this.saxHandler.endCDATA();
    }

    /**
     * <i>[SAX LexicalHandler interface support]</i> Reports an XML
     * comment anywhere in the document.
     *
     * @param  ch     an array holding the characters in the comment.
     * @param  start  the starting position in the array.
     * @param  length the number of characters to use from the array.
     *
     * @throws SAXException   The application may raise an exception.
     */
    public void comment(char ch[], int start, int length)
                                  throws SAXException {
      this.ensureInitialization();
      this.saxHandler.comment(ch, start, length);
    }
  }
}