/trunk/org.mwc.asset.comms/docs/restlet_src/org.restlet.ext.xml/org/restlet/ext/xml/SaxRepresentation.java

/**

 * Copyright 2005-2010 Noelios Technologies.

 * 

 * The contents of this file are subject to the terms of one of the following

 * open source licenses: LGPL 3.0 or LGPL 2.1 or CDDL 1.0 or EPL 1.0 (the

 * "Licenses"). You can select the license that you prefer but you may not use

 * this file except in compliance with one of these Licenses.

 * 

 * You can obtain a copy of the LGPL 3.0 license at

 * http://www.opensource.org/licenses/lgpl-3.0.html

 * 

 * You can obtain a copy of the LGPL 2.1 license at

 * http://www.opensource.org/licenses/lgpl-2.1.php

 * 

 * You can obtain a copy of the CDDL 1.0 license at

 * http://www.opensource.org/licenses/cddl1.php

 * 

 * You can obtain a copy of the EPL 1.0 license at

 * http://www.opensource.org/licenses/eclipse-1.0.php

 * 

 * See the Licenses for the specific language governing permissions and

 * limitations under the Licenses.

 * 

 * Alternatively, you can obtain a royalty free commercial license with less

 * limitations, transferable or non-transferable, directly at

 * http://www.noelios.com/products/restlet-engine

 * 

 * Restlet is a registered trademark of Noelios Technologies.

 */



package org.restlet.ext.xml;



import java.io.IOException;

import java.io.Writer;



import javax.xml.transform.Result;

import javax.xml.transform.TransformerConfigurationException;

import javax.xml.transform.TransformerException;

import javax.xml.transform.TransformerFactory;

import javax.xml.transform.TransformerFactoryConfigurationError;

import javax.xml.transform.dom.DOMSource;

import javax.xml.transform.sax.SAXResult;

import javax.xml.transform.sax.SAXSource;



import org.restlet.data.MediaType;

import org.restlet.representation.Representation;

import org.w3c.dom.Document;

import org.xml.sax.ContentHandler;

import org.xml.sax.InputSource;



/**

 * XML representation for SAX events processing. The purpose is to create a

 * streamable content based on a custom Java object model instead of a neutral

 * DOM tree. This domain object can then be directly modified and efficiently

 * serialized at a later time.<br>

 * <br>

 * Subclasses only need to override the ContentHandler methods required for the

 * reading and also the write(XmlWriter writer) method when serialization is

 * requested.

 * 

 * @author Jerome Louvel

 */

public class SaxRepresentation extends XmlRepresentation {



    /** The SAX source. */

    private volatile SAXSource source;



    /**

     * Default constructor. Uses the {@link MediaType#TEXT_XML} media type.

     */

    public SaxRepresentation() {

        this(MediaType.TEXT_XML);

    }



    /**

     * Constructor.

     * 

     * @param mediaType

     *            The representation media type.

     */

    public SaxRepresentation(MediaType mediaType) {

        super(mediaType);

    }



    /**

     * Constructor.

     * 

     * @param mediaType

     *            The representation's media type.

     * @param xmlDocument

     *            A DOM document to parse.

     */

    public SaxRepresentation(MediaType mediaType, Document xmlDocument) {

        super(mediaType);

        this.source = new SAXSource(SAXSource

                .sourceToInputSource(new DOMSource(xmlDocument)));

    }



    /**

     * Constructor.

     * 

     * @param mediaType

     *            The representation's media type.

     * @param xmlSource

     *            A SAX input source to parse.

     */

    public SaxRepresentation(MediaType mediaType, InputSource xmlSource) {

        super(mediaType);

        this.source = new SAXSource(xmlSource);

    }



    /**

     * Constructor.

     * 

     * @param mediaType

     *            The representation's media type.

     * @param xmlSource

     *            A JAXP source to parse.

     */

    public SaxRepresentation(MediaType mediaType, SAXSource xmlSource) {

        super(mediaType);

        this.source = xmlSource;

    }



    /**

     * Constructor.

     * 

     * @param xmlRepresentation

     *            A source XML representation to parse.

     * @throws IOException

     */

    public SaxRepresentation(Representation xmlRepresentation) {

        super((xmlRepresentation == null) ? null : xmlRepresentation

                .getMediaType());



        try {

            if (xmlRepresentation instanceof XmlRepresentation) {

                this.source = ((XmlRepresentation) xmlRepresentation)

                        .getSaxSource();

            } else {

                this.source = new SAXSource(new InputSource(xmlRepresentation

                        .getReader()));

            }



            if (xmlRepresentation.getLocationRef() != null) {

                this.source.setSystemId(xmlRepresentation.getLocationRef()

                        .getTargetRef().toString());

            }

        } catch (IOException ioe) {

            ioe.printStackTrace();

        }

    }



    @Override

    public InputSource getInputSource() throws IOException {

        return (getSaxSource() == null) ? null : getSaxSource()

                .getInputSource();

    }



    /**

     * Returns the SAX source that can be parsed by the

     * {@link #parse(ContentHandler)} method or used for an XSLT transformation.

     */

    @Override

    public SAXSource getSaxSource() throws IOException {

        return this.source;

    }



    /**

     * Parses the source and sends SAX events to a content handler.

     * 

     * @param contentHandler

     *            The SAX content handler to use for parsing.

     */

    public void parse(ContentHandler contentHandler) throws IOException {

        if (contentHandler != null) {

            try {

                Result result = new SAXResult(contentHandler);

                TransformerFactory.newInstance().newTransformer().transform(

                        this.source, result);

            } catch (TransformerConfigurationException tce) {

                throw new IOException(

                        "Couldn't parse the source representation: "

                                + tce.getMessage());

            } catch (TransformerException te) {

                te.printStackTrace();

                throw new IOException(

                        "Couldn't parse the source representation: "

                                + te.getMessage());

            } catch (TransformerFactoryConfigurationError tfce) {

                throw new IOException(

                        "Couldn't parse the source representation: "

                                + tfce.getMessage());

            }

        } else {

            throw new IOException(

                    "Couldn't parse the source representation: no content restlet defined.");

        }

    }



    /**

     * Releases the namespaces map.

     */

    @Override

    public void release() {

        if (this.source != null) {

            this.source = null;

        }



        super.release();

    }



    /**

     * Sets a SAX source that can be parsed by the

     * {@link #parse(ContentHandler)} method.

     * 

     * @param source

     *            A SAX source.

     */

    public void setSaxSource(SAXSource source) {

        this.source = source;

    }



    @Override

    public void write(Writer writer) throws IOException {

        XmlWriter xmlWriter = new XmlWriter(writer);

        write(xmlWriter);

    }



    /**

     * Writes the representation to a XML writer. The default implementation

     * does nothing and is intended to be overridden.

     * 

     * @param writer

     *            The XML writer to write to.

     * @throws IOException

     */

    public void write(XmlWriter writer) throws IOException {

        // Do nothing by default.

    }

}