jdomsource.java

openlogic-jdom-1.1-all-src-1.zip 可以用于操作xml文件

   * Sets the SAX InputSource to be used for the Source.
   * <p>
   * As this implementation only supports JDOM document as data
   * source, this method always throws an
   * {@link UnsupportedOperationException}.
   * </p>
   *
   * @param  inputSource   a valid InputSource reference.
   *
   * @throws UnsupportedOperationException   always!
   */
  public void setInputSource(InputSource inputSource)
                                  throws UnsupportedOperationException {
    throw new UnsupportedOperationException();
  }

  /**
   * Set the XMLReader to be used for the Source.
   * <p>
   * As this implementation only supports JDOM document as data
   * source, this method throws an
   * {@link UnsupportedOperationException} if the provided reader
   * object does not implement the SAX {@link XMLFilter}
   * interface.  Otherwise, the JDOM document reader will be
   * attached as parent of the filter chain.</p>
   *
   * @param  reader   a valid XMLReader or XMLFilter reference.
   *
   * @throws UnsupportedOperationException   if <code>reader</code>
   *                                         is not a SAX
   *                                         {@link XMLFilter}.
   * @see    #getXMLReader
   */
  public void setXMLReader(XMLReader reader)
                              throws UnsupportedOperationException {
    if (reader instanceof XMLFilter) {
      // Connect the filter chain to a document reader.
      XMLFilter filter = (XMLFilter)reader;
      while (filter.getParent() instanceof XMLFilter) {
        filter = (XMLFilter)(filter.getParent());
      }
      filter.setParent(buildDocumentReader());

      // Read XML data from filter chain.
      this.xmlReader = reader;
    }
    else {
      throw new UnsupportedOperationException();
    }
  }

  /**
   * Returns the XMLReader to be used for the Source.
   * <p>
   * This implementation returns a specific XMLReader reading
   * the XML data from the source JDOM document.
   * </p>
   *
   * @return an XMLReader reading the XML data from the source
   *         JDOM document.
   */
  public XMLReader getXMLReader() {
    if (this.xmlReader == null) {
      this.xmlReader = buildDocumentReader();
    }
    return this.xmlReader;
  }
  
  /**
   * Build an XMLReader to be used for the source. This will
   * create a new instance of DocumentReader with an 
   * EntityResolver instance if available.
   * 
   * @return XMLReader reading the XML data from the source
   * 		JDOM document with an optional EntityResolver
   */
  private XMLReader buildDocumentReader() {
	  DocumentReader reader = new DocumentReader();
	  if (resolver != null)
		  reader.setEntityResolver(resolver);
	  return reader;
  }

  //=========================================================================
  // JDOMInputSource nested class
  //=========================================================================

  /**
   * A subclass of the SAX InputSource interface that wraps a JDOM
   * Document.
   * <p>
   * This class is nested in JDOMSource as it is not intented to
   * be used independently of its friend: DocumentReader.
   * </p>
   *
   * @see    org.jdom.Document
   */
  private static class JDOMInputSource extends InputSource {
    /**
     * The source as a JDOM document or a list of JDOM nodes.
     */
    private Object source = null;

    /**
     * Builds a InputSource wrapping the specified JDOM Document.
     *
     * @param  document   the source document.
     */
    public JDOMInputSource(Document document) {
      this.source = document;
    }

    /**
     * Builds a InputSource wrapping a list of JDOM nodes.
     *
     * @param  nodes   the source JDOM nodes.
     */
    public JDOMInputSource(List nodes) {
      this.source = nodes;
    }

    /**
     * Returns the source.
     *
     * @return the source as a JDOM document or a list of JDOM nodes.
     */
    public Object getSource() {
      return source;
    }

    //-------------------------------------------------------------------------
    // InputSource overwritten methods
    //-------------------------------------------------------------------------

    /**
     * Sets the character stream for this input source.
     * <p>
     * This implementation always throws an
     * {@link UnsupportedOperationException} as the only source
     * stream supported is the source JDOM document.
     * </p>
     *
     * @param  characterStream   a character stream containing
     *                           an XML document.
     *
     * @throws UnsupportedOperationException  always!
     */
    public void setCharacterStream(Reader characterStream)
                                      throws UnsupportedOperationException {
      throw new UnsupportedOperationException();
    }

    /**
     * Gets the character stream for this input source.
     * <p>
     * Note that this method is only provided to make this
     * InputSource implementation acceptable by any XML
     * parser.  As it generates an in-memory string representation
     * of the JDOM document, it is quite inefficient from both
     * speed and memory consumption points of view.
     * </p>
     *
     * @return a Reader to a string representation of the
     *         source JDOM document.
     */
    public Reader getCharacterStream() {
      Object src    = this.getSource();
      Reader reader = null;

      if (src instanceof Document) {
        // Get an in-memory string representation of the document
        // and return a reader on it.
        reader = new StringReader(
                            new XMLOutputter().outputString((Document)src));
      }
      else {
        if (src instanceof List) {
          reader = new StringReader(
                            new XMLOutputter().outputString((List)src));
        }
        // Else: No source, no reader!
      }
      return reader;
    }
  }

  //=========================================================================
  // DocumentReader nested class
  //=========================================================================

  /**
   * An implementation of the SAX2 XMLReader interface that presents
   * a SAX view of a JDOM Document.  The actual generation of the
   * SAX events is delegated to JDOM's SAXOutputter.
   *
   * @see    org.jdom.Document
   * @see    org.jdom.output.SAXOutputter
   */
  private static class DocumentReader   extends    SAXOutputter
                                        implements XMLReader    {
    /**
     * Public default constructor.
     */
    public DocumentReader() {
      super();
    }

    //----------------------------------------------------------------------
    // SAX XMLReader interface support
    //----------------------------------------------------------------------

    /**
     * Parses an XML document from a system identifier (URI).
     * <p>
     * This implementation does not support reading XML data from
     * system identifiers, only from JDOM documents.  Hence,
     * this method always throws a {@link SAXNotSupportedException}.
     * </p>
     *
     * @param  systemId   the system identifier (URI).
     *
     * @throws SAXNotSupportedException   always!
     */
    public void parse(String systemId) throws SAXNotSupportedException {
      throw new SAXNotSupportedException(
                       "Only JDOM Documents are supported as input");
    }

    /**
     * Parses an XML document.
     * <p>
     * The methods accepts only <code>JDOMInputSource</code>s
     * instances as input sources.
     * </p>
     *
     * @param  input   the input source for the top-level of the
     *                  XML document.
     *
     * @throws SAXException               any SAX exception,
     *                                    possibly wrapping
     *                                    another exception.
     * @throws SAXNotSupportedException   if the input source does
     *                                    not wrap a JDOM document.
     */
    public void parse(InputSource input) throws SAXException {
      if (input instanceof JDOMInputSource) {
        try {
          Object source = ((JDOMInputSource)input).getSource();
          if (source instanceof Document) {
            this.output((Document)source);
          }
          else {
            this.output((List)source);
          }
        }
        catch (JDOMException e) {
          throw new SAXException(e.getMessage(), e);
        }
      }
      else {
        throw new SAXNotSupportedException(
                         "Only JDOM Documents are supported as input");
      }
    }
  }
}