xsltview.java

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	 * @see #setSourceKey
	 * @see #convertSource
	 */
	protected Source locateSource(Map model) throws Exception {
		if (this.sourceKey != null) {
			return convertSource(model.get(this.sourceKey));
		}
		Object source = CollectionUtils.findValueOfType(model.values(), getSourceTypes());
		return (source != null ? convertSource(source) : null);
	}

	/**
	 * Return the array of {@link Class Classes} that are supported when converting to an
	 * XSLT {@link Source}.
	 * <p>Currently supports {@link Source}, {@link Document}, {@link Node},
	 * {@link Reader}, {@link InputStream} and {@link Resource}.
	 * @return the supported source types
	 */
	protected Class[] getSourceTypes() {
		return new Class[] {Source.class, Document.class, Node.class, Reader.class, InputStream.class, Resource.class};
	}

	/**
	 * Convert the supplied {@link Object} into an XSLT {@link Source} if the
	 * {@link Object} type is {@link #getSourceTypes() supported}.
	 * @param source the original source object
	 * @return the adapted XSLT Source
	 * @throws IllegalArgumentException if the given Object is not of a supported type
	 */
	protected Source convertSource(Object source) throws Exception {
		if (source instanceof Source) {
			return (Source) source;
		}
		else if (source instanceof Document) {
			return new DOMSource(((Document) source).getDocumentElement());
		}
		else if (source instanceof Node) {
			return new DOMSource((Node) source);
		}
		else if (source instanceof Reader) {
			return new StreamSource((Reader) source);
		}
		else if (source instanceof InputStream) {
			return new StreamSource((InputStream) source);
		}
		else if (source instanceof Resource) {
			return new StreamSource(((Resource) source).getInputStream());
		}
		else {
			throw new IllegalArgumentException("Value '" + source + "' cannot be converted to XSLT Source");
		}
	}

	/**
	 * Configure the supplied {@link Transformer} instance.
	 * <p>The default implementation copies parameters from the model into the
	 * Transformer's {@link Transformer#setParameter parameter set}.
	 * This implementation also copies the {@link #setOutputProperties output properties}
	 * into the {@link Transformer} {@link Transformer#setOutputProperty output properties}.
	 * Indentation properties are set as well.
	 * @param model merged output Map (never <code>null</code>)
	 * @param response current HTTP response
	 * @param transformer the target transformer
	 * @see #copyModelParameters(Map, Transformer)
	 * @see #copyOutputProperties(Transformer)
	 * @see #configureIndentation(Transformer)
	 */
	protected void configureTransformer(Map model, HttpServletResponse response, Transformer transformer) {
		copyModelParameters(model, transformer);
		copyOutputProperties(transformer);
		configureIndentation(transformer);
	}

	/**
	 * Configure the indentation settings for the supplied {@link Transformer}.
	 * @param transformer the target transformer
	 * @throws IllegalArgumentException if the supplied {@link Transformer} is <code>null</code>
	 * @see TransformerUtils#enableIndenting(javax.xml.transform.Transformer) 
	 * @see TransformerUtils#disableIndenting(javax.xml.transform.Transformer)
	 */
	protected final void configureIndentation(Transformer transformer) {
		if (this.indent) {
			TransformerUtils.enableIndenting(transformer);
		}
		else {
			TransformerUtils.disableIndenting(transformer);
		}
	}

	/**
	 * Copy the configured output {@link Properties}, if any, into the
	 * {@link Transformer#setOutputProperty output property set} of the supplied
	 * {@link Transformer}.
	 * @param transformer the target transformer
	 */
	protected final void copyOutputProperties(Transformer transformer) {
		if (this.outputProperties != null) {
			Enumeration en = this.outputProperties.propertyNames();
			while (en.hasMoreElements()) {
				String name = (String) en.nextElement();
				transformer.setOutputProperty(name, this.outputProperties.getProperty(name));
			}
		}
	}

	/**
	 * Copy all entries from the supplied Map into the
	 * {@link Transformer#setParameter(String, Object) parameter set}
	 * of the supplied {@link Transformer}.
	 * @param model merged output Map (never <code>null</code>)
	 * @param transformer the target transformer
	 */
	protected final void copyModelParameters(Map model, Transformer transformer) {
		copyMapEntriesToTransformerParameters(model, transformer);
	}

	/**
	 * Configure the supplied {@link HttpServletResponse}.
	 * <p>The default implementation of this method sets the
	 * {@link HttpServletResponse#setContentType content type} and
	 * {@link HttpServletResponse#setCharacterEncoding encoding}
	 * from the "media-type" and "encoding" output properties
	 * specified in the {@link Transformer}.
	 * @param model merged output Map (never <code>null</code>)
	 * @param response current HTTP response
	 * @param transformer the target transformer
	 */
	protected void configureResponse(Map model, HttpServletResponse response, Transformer transformer) {
		String contentType = getContentType();
		String mediaType = transformer.getOutputProperty(OutputKeys.MEDIA_TYPE);
		String encoding = transformer.getOutputProperty(OutputKeys.ENCODING);
		if (StringUtils.hasText(mediaType)) {
			contentType = mediaType;
		}
		if (StringUtils.hasText(encoding)) {
			// Only apply encoding if content type is specified but does not contain charset clause already.
			if (contentType != null && contentType.toLowerCase().indexOf(WebUtils.CONTENT_TYPE_CHARSET_PREFIX) == -1) {
				contentType = contentType + WebUtils.CONTENT_TYPE_CHARSET_PREFIX + encoding;
			}
		}
		response.setContentType(contentType);
	}

	/**
	 * Load the {@link Templates} instance for the stylesheet at the configured location.
	 */
	private Templates loadTemplates() throws ApplicationContextException {
		Source stylesheetSource = getStylesheetSource();
		try {
			Templates templates = this.transformerFactory.newTemplates(stylesheetSource);
			if (logger.isDebugEnabled()) {
				logger.debug("Loading templates '" + templates + "'");
			}
			return templates;
		}
		catch (TransformerConfigurationException ex) {
			throw new ApplicationContextException("Can't load stylesheet from '" + getUrl() + "'", ex);
		}
		finally {
			closeSourceIfNecessary(stylesheetSource);
		}
	}

	/**
	 * Create the {@link Transformer} instance used to prefer the XSLT transformation.
	 * <p>The default implementation simply calls {@link Templates#newTransformer()}, and
	 * configures the {@link Transformer} with the custom {@link URIResolver} if specified.
	 * @param templates the XSLT Templates instance to create a Transformer for
	 */
	protected Transformer createTransformer(Templates templates) throws TransformerConfigurationException {
		Transformer transformer = templates.newTransformer();
		if (this.uriResolver != null) {
			transformer.setURIResolver(this.uriResolver);
		}
		return transformer;
	}

	/**
	 * Get the XSLT {@link Source} for the XSLT template under the {@link #setUrl configured URL}.
	 */
	protected Source getStylesheetSource() {
		String url = getUrl();
		if (logger.isDebugEnabled()) {
			logger.debug("Loading XSLT stylesheet from '" + url + "'");
		}
		try {
			Resource stylesheetResource = getApplicationContext().getResource(url);
			String systemId = url.substring(0, url.lastIndexOf('/') + 1);
			return new StreamSource(stylesheetResource.getInputStream(), systemId);
		}
		catch (IOException ex) {
			throw new ApplicationContextException("Can't load XSLT stylesheet from '" + url + "'", ex);
		}
	}

	/**
	 * Copy all {@link Map.Entry entries} from the supplied {@link Map} into the
	 * {@link Transformer#setParameter(String, Object) parameter set} of the supplied
	 * {@link Transformer}.
	 */
	private void copyMapEntriesToTransformerParameters(Map map, Transformer transformer) {
		for (Iterator iterator = map.entrySet().iterator(); iterator.hasNext();) {
			Map.Entry entry = (Map.Entry) iterator.next();
			transformer.setParameter(ObjectUtils.nullSafeToString(entry.getKey()), entry.getValue());
		}
	}

	/**
	 * Close the underlying resource managed by the supplied {@link Source} if applicable.
	 * <p>Only works for {@link StreamSource StreamSources}.
	 * @param source the XSLT Source to close (may be <code>null</code>)
	 */
	private void closeSourceIfNecessary(Source source) {
		if (source instanceof StreamSource) {
			StreamSource streamSource = (StreamSource) source;
			if (streamSource.getReader() != null) {
				try {
					streamSource.getReader().close();
				}
				catch (IOException ex) {
				}
			}
			if (streamSource.getInputStream() != null) {
				try {
					streamSource.getInputStream().close();
				}
				catch (IOException ex) {
				}
			}
		}
	}

}