org.thymeleaf.extras.tiles2.renderer.ThymeleafAttributeRenderer Maven / Gradle / Ivy
/*
* =============================================================================
*
* Copyright (c) 2011-2013, The THYMELEAF team (http://www.thymeleaf.org)
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* =============================================================================
*/
package org.thymeleaf.extras.tiles2.renderer;
import java.io.IOException;
import java.util.Map;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.jsp.PageContext;
import org.apache.tiles.Attribute;
import org.apache.tiles.context.TilesRequestContext;
import org.apache.tiles.impl.InvalidTemplateException;
import org.apache.tiles.jsp.context.JspTilesRequestContext;
import org.apache.tiles.renderer.impl.AbstractTypeDetectingAttributeRenderer;
import org.apache.tiles.servlet.context.ServletTilesRequestContext;
import org.apache.tiles.servlet.context.ServletUtil;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.thymeleaf.Configuration;
import org.thymeleaf.TemplateEngine;
import org.thymeleaf.context.IProcessingContext;
import org.thymeleaf.dialect.IDialect;
import org.thymeleaf.dom.DOMSelector;
import org.thymeleaf.exceptions.ConfigurationException;
import org.thymeleaf.exceptions.TemplateProcessingException;
import org.thymeleaf.extras.tiles2.dialect.TilesDialect;
import org.thymeleaf.extras.tiles2.dialect.processor.TilesFragmentAttrProcessor;
import org.thymeleaf.extras.tiles2.naming.ThymeleafTilesNaming;
import org.thymeleaf.fragment.DOMSelectorFragmentSpec;
import org.thymeleaf.fragment.IFragmentSpec;
import org.thymeleaf.fragment.WholeFragmentSpec;
import org.thymeleaf.standard.StandardDialect;
import org.thymeleaf.standard.fragment.StandardFragment;
import org.thymeleaf.standard.fragment.StandardFragmentProcessor;
import org.thymeleaf.standard.fragment.StandardFragmentSignatureNodeReferenceChecker;
/**
*
* @author Daniel Fernández
*
*/
public class ThymeleafAttributeRenderer
extends AbstractTypeDetectingAttributeRenderer {
private static final Logger logger = LoggerFactory.getLogger(ThymeleafAttributeRenderer.class);
private static final String SPRING3_STANDARD_DIALECT_CLASS_NAME =
"org.thymeleaf.spring3.dialect.SpringStandardDialect";
private static final String SPRING4_STANDARD_DIALECT_CLASS_NAME =
"org.thymeleaf.spring4.dialect.SpringStandardDialect";
public ThymeleafAttributeRenderer() {
super();
}
@Override
public void write(final Object value, final Attribute attribute,
final TilesRequestContext tilesRequestContext) throws IOException {
if (value == null) {
throw new InvalidTemplateException("Cannot render a null template");
}
if (!(value instanceof String)) {
throw new InvalidTemplateException(
"Cannot render a template that is not a String ('" + value.getClass().getName() +"')");
}
if (logger.isDebugEnabled()) {
logger.debug("[THYMELEAF][TILES] Rendering Thymeleaf Tiles attribute with value \"{}\"", new Object[] {value});
}
final ServletTilesRequestContext requestContext =
ServletUtil.getServletRequest(tilesRequestContext);
final String templateSelector = ((String) value).trim();
final HttpServletRequest request = requestContext.getRequest();
final HttpServletResponse response = requestContext.getResponse();
final TemplateEngine templateEngine =
(TemplateEngine) request.getAttribute(ThymeleafTilesNaming.TEMPLATE_ENGINE_ATTRIBUTE_NAME);
final IProcessingContext processingContext =
(IProcessingContext) request.getAttribute(ThymeleafTilesNaming.PROCESSING_CONTEXT_ATTRIBUTE_NAME);
// This one could be null!
final FragmentMetadata fragmentBehaviour =
(FragmentMetadata) request.getAttribute(ThymeleafTilesNaming.FRAGMENT_METADATA_ATTRIBUTE_NAME);
// Once retrieved, we have to remove it in order to avoid it affecting other templates
request.removeAttribute(ThymeleafTilesNaming.FRAGMENT_METADATA_ATTRIBUTE_NAME);
if (tilesRequestContext instanceof JspTilesRequestContext) {
// If our Thymeleaf template is being executed from a JSP, we should
// first flush the associated JspWriter (because it will be buffering
// instead of directly writing to the response.getWriter() we will be writing.
if (logger.isTraceEnabled()) {
logger.trace("[THYMELEAF][TILES] Current Tiles Request Context is a JSP" +
"context. Flushing JspWriter to avoid fragment writing order " +
"problems.");
}
final JspTilesRequestContext jspTilesRequestContext = (JspTilesRequestContext) tilesRequestContext;
final PageContext pageContext = jspTilesRequestContext.getPageContext();
pageContext.getOut().flush();
}
final boolean displayOnlySelectionChildren =
(fragmentBehaviour != null? fragmentBehaviour.isDisplayOnlyChildren() : false);
final TilesFragment fragment =
computeTemplateSelector(templateEngine, processingContext, templateSelector);
final String templateName = fragment.getTemplateName();
IFragmentSpec fragmentSpec = fragment.getFragmentSpec();
if (displayOnlySelectionChildren) {
fragmentSpec = new FragmentSpecRootRemovingWrapper(fragmentSpec);
}
templateEngine.process(templateName, processingContext, fragmentSpec, response.getWriter());
if (logger.isDebugEnabled()) {
logger.debug("[THYMELEAF][TILES] Rendered Thymeleaf Tiles attribute with value \"{}\"", new Object[] {value});
}
}
private static TilesFragment computeTemplateSelector(final TemplateEngine templateEngine,
final IProcessingContext processingContext, final String templateSelector) {
if (!templateEngine.isInitialized()) {
templateEngine.initialize();
}
if (!isStandardDialectPresent(templateEngine)) {
return computeNonStandardFragment(templateEngine, templateSelector);
}
final Configuration configuration = templateEngine.getConfiguration();
final String tilesDialectPrefix = getTilesDialectPrefix(templateEngine);
final StandardFragment standardFragment =
StandardFragmentProcessor.computeStandardFragmentSpec(configuration, processingContext,
templateSelector, tilesDialectPrefix, TilesFragmentAttrProcessor.ATTR_NAME);
return new TilesFragment(standardFragment);
}
private static boolean isStandardDialectPresent(final TemplateEngine templateEngine) {
try {
final Class springStandardDialectClass =
Class.forName(SPRING3_STANDARD_DIALECT_CLASS_NAME);
if (isDialectPresent(templateEngine, springStandardDialectClass)) {
return true;
}
} catch (final ClassNotFoundException e) {
// nothing to do, just do other checks
}
try {
final Class springStandardDialectClass =
Class.forName(SPRING4_STANDARD_DIALECT_CLASS_NAME);
if (isDialectPresent(templateEngine, springStandardDialectClass)) {
return true;
}
} catch (final ClassNotFoundException e) {
// nothing to do, just do other checks
}
return isDialectPresent(templateEngine, StandardDialect.class);
}
private static boolean isDialectPresent(final TemplateEngine templateEngine, final Class dialectClass) {
for (final IDialect dialect : templateEngine.getDialects()) {
if (dialectClass.isAssignableFrom(dialect.getClass())) {
return true;
}
}
return false;
}
/*
* Syntax is like the standard one, only without expression evaluation:
* TEMPLATE_NAME :: FRAGMENT_NAME
* TEMPLATE_NAME :: [DOM_SELECTOR]
*/
private static TilesFragment computeNonStandardFragment(
final TemplateEngine templateEngine, final String templateSelector) {
// Note template names in Tiles2 cannot be null (no way of executing the fragment on the "current" template)
if (templateSelector.trim().endsWith(")")) {
// It seems that parameters have been specified, which is forbidden if the Standard Dialect is not enabled.
throw new TemplateProcessingException(
"Cannot process template selector \"" + templateSelector + "\": The Thymeleaf Standard Dialect " +
"has not been enabled, and therefore no parameters can be allowed for fragments.");
}
final int separatorPos = templateSelector.indexOf("::");
if (separatorPos < 0) {
return new TilesFragment(templateSelector, WholeFragmentSpec.INSTANCE);
}
final String templateName = templateSelector.substring(0, separatorPos).trim();
String fragmentSelector = templateSelector.substring(separatorPos + 2).trim();
if (fragmentSelector.length() > 3 &&
fragmentSelector.charAt(0) == '[' && fragmentSelector.charAt(fragmentSelector.length() - 1) == ']' &&
fragmentSelector.charAt(fragmentSelector.length() - 2) != '\'') {
// For legacy compatibility reasons, we allow fragment DOM Selector expressions to be specified
// between brackets. Just remove them.
fragmentSelector = fragmentSelector.substring(1, fragmentSelector.length() - 1);
}
final String tilesDialectPrefix = getTilesDialectPrefix(templateEngine);
final DOMSelector.INodeReferenceChecker nodeReferenceChecker =
new StandardFragmentSignatureNodeReferenceChecker(
templateEngine.getConfiguration(), tilesDialectPrefix, TilesFragmentAttrProcessor.ATTR_NAME);
final IFragmentSpec fragmentSpec = new DOMSelectorFragmentSpec(fragmentSelector, nodeReferenceChecker);
return new TilesFragment(templateName, fragmentSpec);
}
private static String getTilesDialectPrefix(final TemplateEngine templateEngine) {
for (final Map.Entry dialectByPrefix : templateEngine.getDialectsByPrefix().entrySet()) {
final IDialect dialect = dialectByPrefix.getValue();
if (TilesDialect.class.isAssignableFrom(dialect.getClass())) {
return dialectByPrefix.getKey();
}
}
throw new ConfigurationException(
"Tiles dialect has not been found. In order to use Apache Tiles with Thymeleaf, you should configure " +
"the " + TilesDialect.class.getName() + " dialect at your Template Engine");
}
public boolean isRenderable(final Object value, final Attribute attribute,
final TilesRequestContext request) {
// Thyemeleaf cannot give a real answer to this as resources are made available to
// the processing core only by means of actually reading them (the type of resource is
// hidden by the ITemplateResolver / IResourceResolver), and it could be that
// there is no way of knowing if a resource is available or not before actually
// reading it.
//
// So this attribute renderer, when chained, should be always put at the end of the chain.
return true;
}
}
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