abstractxsltview.java

spring api 源代码

				return (TransformerFactory) transformerFactoryClass.newInstance();
			}
			catch (Exception ex) {
				throw new TransformerFactoryConfigurationError(ex, "Could not instantiate TransformerFactory");
			}
		}
		else {
			return TransformerFactory.newInstance();
		}
	}

	/**
	 * Return the TransformerFactory used by this view.
	 * Available once the View object has been fully initialized.
	 */
	protected final TransformerFactory getTransformerFactory() {
		return this.transformerFactory;
	}


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

		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
	 * or for the ServletResponse Writer (according to {@link #useWriter()}).
	 * @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()
	 * @see javax.servlet.ServletResponse#getWriter()
	 * @see #useWriter()
	 */
	protected void doTransform(
			Map model, Source source, HttpServletRequest request, HttpServletResponse response)
			throws Exception {

		Map parameters = getParameters(model, request);
		Result result = (useWriter() ?
				new StreamResult(response.getWriter()) :
				new StreamResult(new BufferedOutputStream(response.getOutputStream())));
		String encoding = response.getCharacterEncoding();
		doTransform(source, parameters, result, encoding);
	}

	/**
	 * 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
	 * {@link #getParameters(HttpServletRequest)} variant.
	 * @param model the model Map
	 * @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(Map model, HttpServletRequest request) {
		return getParameters(request);
	}

	/**
	 * 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()} variant.
	 * @param request current HTTP request
	 * @return a Map of parameters to apply to the transformation process
	 * @see #getParameters(Map, HttpServletRequest)
	 * @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.
	 * @return a Map of parameters to apply to the transformation process
	 * @deprecated as of Spring 2.0.4, in favor of the
	 * {@link #getParameters(HttpServletRequest)} variant
	 */
	protected Map getParameters() {
		return null;
	}

	/**
	 * Return whether to use a <code>java.io.Writer</code> to write text content
	 * to the HTTP response. Else, a <code>java.io.OutputStream</code> will be used,
	 * to write binary content to the response.
	 * <p>The default implementation returns <code>false</code>, indicating a
	 * a <code>java.io.OutputStream</code>.
	 * @return whether to use a Writer (<code>true</code>) or an OutputStream
	 * (<code>false</code>)
	 * @see javax.servlet.ServletResponse#getWriter()
	 * @see javax.servlet.ServletResponse#getOutputStream()
	 */
	protected boolean useWriter() {
		return false;
	}


	/**
	 * 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
	 * (as determined by {@link #getParameters(Map, HttpServletRequest)})
	 * @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 = buildTransformer(parameters);

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

			// 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);
		}
		catch (TransformerConfigurationException ex) {
			throw new NestedServletException(
					"Couldn't create XSLT transformer in XSLT view with name [" + getBeanName() + "]", ex);
		}
		catch (TransformerException ex) {
			throw new NestedServletException(
					"Couldn't perform transform in XSLT view with name [" + getBeanName() + "]", ex);
		}
	}

	/**
	 * Build a Transformer object for immediate use, based on the
	 * given parameters.
	 * @param parameters a Map of parameters to be applied to the stylesheet
	 * (as determined by {@link #getParameters(Map, HttpServletRequest)})
	 * @return the Transformer object (never <code>null</code>)
	 * @throws TransformerConfigurationException if the Transformer object
	 * could not be built
	 */
	protected Transformer buildTransformer(Map parameters) throws TransformerConfigurationException {
		Templates templates = getTemplates();
		Transformer transformer =
				(templates != null ? templates.newTransformer() : getTransformerFactory().newTransformer());
		applyTransformerParameters(parameters, transformer);
		return transformer;
	}

	/**
	 * Obtain the Templates object to use, based on the configured
	 * stylesheet, either a cached one or a freshly built one.
	 * <p>Subclasses may override this method e.g. in order to refresh
	 * the Templates instance, calling {@link #resetCachedTemplates()}
	 * before delegating to this <code>getTemplates()</code> implementation.
	 * @return the Templates object (or <code>null</code> if there is
	 * no stylesheet specified)
	 * @throws TransformerConfigurationException if the Templates object
	 * could not be built
	 * @see #setStylesheetLocation
	 * @see #setCache
	 * @see #resetCachedTemplates
	 */
	protected Templates getTemplates() throws TransformerConfigurationException {
		if (this.cachedTemplates != null) {
			return this.cachedTemplates;
		}
		Resource location = getStylesheetLocation();
		if (location != null) {
			Templates templates = getTransformerFactory().newTemplates(getStylesheetSource(location));
			if (this.cache) {
				this.cachedTemplates = templates;
			}
			return templates;
		}
		return null;
	}

	/**
	 * Apply the specified parameters to the given Transformer.
	 * @param parameters the transformer parameters
	 * (as determined by {@link #getParameters(Map, HttpServletRequest)})
	 * @param transformer the Transformer to aply the parameters
	 */
	protected void applyTransformerParameters(Map parameters, Transformer transformer) {
		if (parameters != null) {
			for (Iterator it = parameters.entrySet().iterator(); it.hasNext();) {
				Map.Entry entry = (Map.Entry) it.next();
				transformer.setParameter(entry.getKey().toString(), entry.getValue());
			}
		}
	}

	/**
	 * Load the stylesheet from the specified location.
	 * @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);
		}
	}

}