abstractxsltview.java

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	}

	private synchronized void cacheTemplates() throws ApplicationContextException {
		if (this.stylesheetLocation != null) {
			try {
				this.templates = this.transformerFactory.newTemplates(getStylesheetSource(this.stylesheetLocation));
				if (logger.isDebugEnabled()) {
					logger.debug("Loaded templates [" + this.templates + "] in XSLT view '" + getBeanName() + "'");
				}
			}
			catch (TransformerConfigurationException ex) {
				throw new ApplicationContextException("Can't load stylesheet from " + this.stylesheetLocation +
						" in XSLT view '" + getBeanName() + "'", ex);
			}
		}
	}

	/**
	 * Load the stylesheet.
	 * @param stylesheetLocation the stylesheet resource to be loaded
	 * @return the stylesheet source
     * @throws ApplicationContextException if the stylesheet resource could not be loaded
	 */
	protected Source getStylesheetSource(Resource stylesheetLocation) throws ApplicationContextException {
		if (logger.isDebugEnabled()) {
			logger.debug("Loading XSLT stylesheet from " + stylesheetLocation);
		}
		try {
			URL url = stylesheetLocation.getURL();
			String urlPath = url.toString();
			String systemId = urlPath.substring(0, urlPath.lastIndexOf('/') + 1);
			return new StreamSource(url.openStream(), systemId);
		}
		catch (IOException ex) {
			throw new ApplicationContextException("Can't load XSLT stylesheet from " + stylesheetLocation, ex);
		}
	}

	protected final void renderMergedOutputModel(
			Map model, HttpServletRequest request, HttpServletResponse response) throws Exception {

		if (!this.cache) {
			logger.warn("DEBUG SETTING: NOT THREADSAFE AND WILL IMPAIR PERFORMANCE: template will be refreshed");
			cacheTemplates();
		}

		if (this.templates == null) {
			if (this.transformerFactory == null) {
				throw new ServletException("XLST view is incorrectly configured. Templates AND TransformerFactory are null");
			}

			logger.warn("XSLT view is not configured: will copy XML input");
			response.setContentType("text/xml; charset=ISO-8859-1");
		}
		else {
			// normal case
			response.setContentType(getContentType());
		}

		Source source = null;
		String docRoot = null;

		// Value of a single element in the map, if there is one.
		Object singleModel = null;

		if (this.useSingleModelNameAsRoot && model.size() == 1) {
			docRoot = (String) model.keySet().iterator().next();
			if (logger.isDebugEnabled()) {
				logger.debug("Single model object received, key [" + docRoot + "] will be used as root tag");
			}
			singleModel = model.get(docRoot);
		}

		// Handle special case when we have a single node.
		if (singleModel instanceof Node || singleModel instanceof Source) {
			// Don't domify if the model is already an XML node/source.
			// We don't need to worry about model name, either:
			// we leave the Node alone.
			logger.debug("No need to domify: was passed an XML Node or Source");
			source = (singleModel instanceof Node ? new DOMSource((Node) singleModel) : (Source) singleModel);
		}
		else {
			// docRoot local variable takes precedence
			source = createXsltSource(model, (docRoot != null ? docRoot : this.root), request, response);
		}

		doTransform(model, source, request, response);
	}

	/**
	 * Return the XML {@link Source} to transform.
	 * @param model the model Map
	 * @param root name for root element. This can be supplied as a bean property
	 * to concrete subclasses within the view definition file, but will be overridden
	 * in the case of a single object in the model map to be the key for that object.
	 * If no root property is specified and multiple model objects exist, a default
	 * root tag name will be supplied.
	 * @param request HTTP request. Subclasses won't normally use this, as
	 * request processing should have been complete. However, we might want to
	 * create a RequestContext to expose as part of the model.
	 * @param response HTTP response. Subclasses won't normally use this,
	 * however there may sometimes be a need to set cookies.
	 * @return the XSLT Source to transform
	 * @throws Exception if an error occurs
	 */
	protected Source createXsltSource(
			Map model, String root, HttpServletRequest request, HttpServletResponse response)
			throws Exception {

		return null;
	}

	/**
	 * Perform the actual transformation, writing to the HTTP response.
	 * <p>The default implementation delegates to the
	 * {@link #doTransform(javax.xml.transform.Source, java.util.Map, javax.xml.transform.Result, String)}
	 * method , building a StreamResult for the ServletResponse OutputStream.
	 * @param model the model Map
	 * @param source the Source to transform
	 * @param request current HTTP request
	 * @param response current HTTP response
	 * @throws Exception if an error occurs
	 * @see javax.xml.transform.stream.StreamResult
	 * @see javax.servlet.ServletResponse#getOutputStream
	 */
	protected void doTransform(
			Map model, Source source, HttpServletRequest request, HttpServletResponse response)
			throws Exception {

		doTransform(source, getParameters(request),
				new StreamResult(new BufferedOutputStream(response.getOutputStream())),
				response.getCharacterEncoding());
	}

	/**
	 * Perform the actual transformation, writing to the given result.
	 * @param source the Source to transform
	 * @param parameters a Map of parameters to be applied to the stylesheet
	 * @param result the result to write to
     * @param encoding the preferred character encoding that the underlying Transformer should use
	 * @throws Exception if an error occurs
	 */
	protected void doTransform(Source source, Map parameters, Result result, String encoding)
			throws Exception {

		try {
			Transformer trans = (this.templates != null) ?
					this.templates.newTransformer() : // we have a stylesheet
					this.transformerFactory.newTransformer(); // just a copy

			// Explicitly apply URIResolver to every created Transformer.
			if (this.uriResolver != null) {
				trans.setURIResolver(this.uriResolver);
			}

			// Apply any subclass supplied parameters to the transformer.
			if (parameters != null) {
				for (Iterator it = parameters.entrySet().iterator(); it.hasNext();) {
					Map.Entry entry = (Map.Entry) it.next();
					trans.setParameter(entry.getKey().toString(), entry.getValue());
				}
				if (logger.isDebugEnabled()) {
					logger.debug("Added parameters [" + parameters + "] to transformer object");
				}
			}

			// Specify default output properties.
			trans.setOutputProperty(OutputKeys.ENCODING, encoding);
			if (this.indent) {
				TransformerUtils.enableIndenting(trans);
			}

			// Apply any arbitrary output properties, if specified.
			if (this.outputProperties != null) {
				Enumeration propsEnum = this.outputProperties.propertyNames();
				while (propsEnum.hasMoreElements()) {
					String propName = (String) propsEnum.nextElement();
					trans.setOutputProperty(propName, this.outputProperties.getProperty(propName));
				}
			}

			// Perform the actual XSLT transformation.
			trans.transform(source, result);
			if (logger.isDebugEnabled()) {
				logger.debug("XSLT transformed with stylesheet [" + this.stylesheetLocation + "]");
			}
		}
		catch (TransformerConfigurationException ex) {
			throw new NestedServletException("Couldn't create XSLT transformer for stylesheet [" +
					this.stylesheetLocation + "] in XSLT view with name [" + getBeanName() + "]", ex);
		}
		catch (TransformerException ex) {
			throw new NestedServletException("Couldn't perform transform with stylesheet [" +
					this.stylesheetLocation + "] in XSLT view with name [" + getBeanName() + "]", ex);
		}
	}

	/**
	 * Return a Map of transformer parameters to be applied to the stylesheet.
	 * <p>Subclasses can override this method in order to apply one or more
	 * parameters to the transformation process.
	 * <p>The default implementation delegates to the simple {@link #getParameters()}
	 * version.
	 * @param request current HTTP request
	 * @return a Map of parameters to apply to the transformation process
	 * @see #getParameters()
	 * @see javax.xml.transform.Transformer#setParameter
	 */
	protected Map getParameters(HttpServletRequest request) {
		return getParameters();
	}

	/**
	 * Return a Map of transformer parameters to be applied to the stylesheet.
	 * <p>Subclasses can override this method in order to apply one or more
	 * parameters to the transformation process.
	 * <p>The default implementation simply returns <code>null</code>.
	 * @return a Map of parameters to apply to the transformation process
	 * @see #getParameters(HttpServletRequest)
	 * @see javax.xml.transform.Transformer#setParameter
	 */
	protected Map getParameters() {
		return null;
	}

}