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Modern server-side Java template engine for both web and standalone environments
/*
* =============================================================================
*
* Copyright (c) 2011-2018, 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.spring5.view;
import java.io.Writer;
import java.lang.reflect.Field;
import java.nio.charset.Charset;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.Locale;
import java.util.Map;
import java.util.Set;
import javax.servlet.ServletContext;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.context.ApplicationContext;
import org.springframework.core.convert.ConversionService;
import org.springframework.web.servlet.View;
import org.springframework.web.servlet.support.RequestContext;
import org.springframework.web.servlet.view.AbstractTemplateView;
import org.thymeleaf.IEngineConfiguration;
import org.thymeleaf.context.WebExpressionContext;
import org.thymeleaf.exceptions.TemplateProcessingException;
import org.thymeleaf.spring5.ISpringTemplateEngine;
import org.thymeleaf.spring5.context.webmvc.SpringWebMvcThymeleafRequestContext;
import org.thymeleaf.spring5.expression.ThymeleafEvaluationContext;
import org.thymeleaf.spring5.naming.SpringContextVariableNames;
import org.thymeleaf.spring5.util.SpringContentTypeUtils;
import org.thymeleaf.standard.expression.FragmentExpression;
import org.thymeleaf.standard.expression.IStandardExpressionParser;
import org.thymeleaf.standard.expression.StandardExpressions;
import org.thymeleaf.util.FastStringWriter;
/**
*
* Base implementation of the Spring WebMVC {@link org.springframework.web.servlet.View}
* interface.
*
*
* Views represent a template being executed, after being resolved (and
* instantiated) by a {@link org.springframework.web.servlet.ViewResolver}.
*
*
* This is the default view implementation resolved by {@link ThymeleafViewResolver}.
*
*
* @author Daniel Fernández
*
* @since 3.0.3
*
*/
public class ThymeleafView
extends AbstractThymeleafView {
/*
* If this is not null, we are using Spring 3.1+ and there is the possibility
* to automatically add @PathVariable's to models. This will be computed at class
* initialization time.
*/
private static final String pathVariablesSelector;
private Set markupSelectors = null;
static {
/*
* Compute whether we can obtain @PathVariable's from the request and add them
* automatically to the model (Spring 3.1+)
*/
String pathVariablesSelectorValue = null;
try {
// We are looking for the value of the View.PATH_VARIABLES constant, which is a String
final Field pathVariablesField = View.class.getDeclaredField("PATH_VARIABLES");
pathVariablesSelectorValue = (String) pathVariablesField.get(null);
} catch (final NoSuchFieldException ignored) {
pathVariablesSelectorValue = null;
} catch (final IllegalAccessException ignored) {
pathVariablesSelectorValue = null;
}
pathVariablesSelector = pathVariablesSelectorValue;
}
/**
*
* Creates a new instance of {@code ThymeleafView}.
*
*/
public ThymeleafView() {
super();
}
/**
*
* Creates a new instance of {@code ThymeleafView}, specifying the
* template name.
*
*
* @param templateName the template name.
*/
public ThymeleafView(final String templateName) {
super(templateName);
}
/**
*
* Returns the markup selector defining the part of the template that should
* be processed.
*
*
* This selector will be used for selecting the section of the template
* that should be processed, discarding the rest of the template. If null,
* the whole template will be processed.
*
*
* Subclasses of {@link ThymeleafView} might choose not to honor this parameter,
* disallowing the processing of template fragments.
*
*
* @return the markup selector currently set, or null of no fragment has been
* specified yet.
*/
public String getMarkupSelector() {
return (this.markupSelectors == null || this.markupSelectors.size() == 0? null : this.markupSelectors.iterator().next());
}
/**
*
* Sets the markup selector defining the part of the template that should
* be processed.
*
*
* This selector will be used for selecting the section of the template
* that should be processed, discarding the rest of the template. If null,
* the whole template will be processed.
*
*
* Subclasses of {@link ThymeleafView} might choose not to honor this parameter,
* disallowing the processing of template fragments.
*
*
* @param markupSelector the markup selector to be set.
*/
public void setMarkupSelector(final String markupSelector) {
this.markupSelectors =
(markupSelector == null || markupSelector.trim().length() == 0? null : Collections.singleton(markupSelector.trim()));
}
public void render(final Map model, final HttpServletRequest request, final HttpServletResponse response)
throws Exception {
renderFragment(this.markupSelectors, model, request, response);
}
protected void renderFragment(final Set markupSelectorsToRender, final Map model, final HttpServletRequest request,
final HttpServletResponse response)
throws Exception {
final ServletContext servletContext = getServletContext() ;
final String viewTemplateName = getTemplateName();
final ISpringTemplateEngine viewTemplateEngine = getTemplateEngine();
if (viewTemplateName == null) {
throw new IllegalArgumentException("Property 'templateName' is required");
}
if (getLocale() == null) {
throw new IllegalArgumentException("Property 'locale' is required");
}
if (viewTemplateEngine == null) {
throw new IllegalArgumentException("Property 'templateEngine' is required");
}
final Map mergedModel = new HashMap(30);
final Map templateStaticVariables = getStaticVariables();
if (templateStaticVariables != null) {
mergedModel.putAll(templateStaticVariables);
}
if (pathVariablesSelector != null) {
@SuppressWarnings("unchecked")
final Map pathVars = (Map) request.getAttribute(pathVariablesSelector);
if (pathVars != null) {
mergedModel.putAll(pathVars);
}
}
if (model != null) {
mergedModel.putAll(model);
}
final ApplicationContext applicationContext = getApplicationContext();
final RequestContext requestContext =
new RequestContext(request, response, getServletContext(), mergedModel);
final SpringWebMvcThymeleafRequestContext thymeleafRequestContext =
new SpringWebMvcThymeleafRequestContext(requestContext, request);
// For compatibility with ThymeleafView
addRequestContextAsVariable(mergedModel, SpringContextVariableNames.SPRING_REQUEST_CONTEXT, requestContext);
// For compatibility with AbstractTemplateView
addRequestContextAsVariable(mergedModel, AbstractTemplateView.SPRING_MACRO_REQUEST_CONTEXT_ATTRIBUTE, requestContext);
// Add the Thymeleaf RequestContext wrapper that we will be using in this dialect (the bare RequestContext
// stays in the context to for compatibility with other dialects)
mergedModel.put(SpringContextVariableNames.THYMELEAF_REQUEST_CONTEXT, thymeleafRequestContext);
// Expose Thymeleaf's own evaluation context as a model variable
//
// Note Spring's EvaluationContexts are NOT THREAD-SAFE (in exchange for SpelExpressions being thread-safe).
// That's why we need to create a new EvaluationContext for each request / template execution, even if it is
// quite expensive to create because of requiring the initialization of several ConcurrentHashMaps.
final ConversionService conversionService =
(ConversionService) request.getAttribute(ConversionService.class.getName()); // might be null!
final ThymeleafEvaluationContext evaluationContext =
new ThymeleafEvaluationContext(applicationContext, conversionService);
mergedModel.put(ThymeleafEvaluationContext.THYMELEAF_EVALUATION_CONTEXT_CONTEXT_VARIABLE_NAME, evaluationContext);
final IEngineConfiguration configuration = viewTemplateEngine.getConfiguration();
final WebExpressionContext context =
new WebExpressionContext(configuration, request, response, servletContext, getLocale(), mergedModel);
final String templateName;
final Set markupSelectors;
if (!viewTemplateName.contains("::")) {
// No fragment specified at the template name
templateName = viewTemplateName;
markupSelectors = null;
} else {
// Template name contains a fragment name, so we should parse it as such
final IStandardExpressionParser parser = StandardExpressions.getExpressionParser(configuration);
final FragmentExpression fragmentExpression;
try {
// By parsing it as a standard expression, we might profit from the expression cache
fragmentExpression = (FragmentExpression) parser.parseExpression(context, "~{" + viewTemplateName + "}");
} catch (final TemplateProcessingException e) {
throw new IllegalArgumentException("Invalid template name specification: '" + viewTemplateName + "'");
}
final FragmentExpression.ExecutedFragmentExpression fragment =
FragmentExpression.createExecutedFragmentExpression(context, fragmentExpression);
templateName = FragmentExpression.resolveTemplateName(fragment);
markupSelectors = FragmentExpression.resolveFragments(fragment);
final Map nameFragmentParameters = fragment.getFragmentParameters();
if (nameFragmentParameters != null) {
if (fragment.hasSyntheticParameters()) {
// We cannot allow synthetic parameters because there is no way to specify them at the template
// engine execution!
throw new IllegalArgumentException(
"Parameters in a view specification must be named (non-synthetic): '" + viewTemplateName + "'");
}
context.setVariables(nameFragmentParameters);
}
}
final String templateContentType = getContentType();
final Locale templateLocale = getLocale();
final String templateCharacterEncoding = getCharacterEncoding();
final Set processMarkupSelectors;
if (markupSelectors != null && markupSelectors.size() > 0) {
if (markupSelectorsToRender != null && markupSelectorsToRender.size() > 0) {
throw new IllegalArgumentException(
"A markup selector has been specified (" + Arrays.asList(markupSelectors) + ") for a view " +
"that was already being executed as a fragment (" + Arrays.asList(markupSelectorsToRender) + "). " +
"Only one fragment selection is allowed.");
}
processMarkupSelectors = markupSelectors;
} else {
if (markupSelectorsToRender != null && markupSelectorsToRender.size() > 0) {
processMarkupSelectors = markupSelectorsToRender;
} else {
processMarkupSelectors = null;
}
}
response.setLocale(templateLocale);
if (!getForceContentType()) {
final String computedContentType =
SpringContentTypeUtils.computeViewContentType(
request,
(templateContentType != null? templateContentType : DEFAULT_CONTENT_TYPE),
(templateCharacterEncoding != null? Charset.forName(templateCharacterEncoding) : null));
response.setContentType(computedContentType);
} else {
// We will force the content type parameters without trying to make smart assumptions over them
if (templateContentType != null) {
response.setContentType(templateContentType);
} else {
response.setContentType(DEFAULT_CONTENT_TYPE);
}
if (templateCharacterEncoding != null) {
response.setCharacterEncoding(templateCharacterEncoding);
}
}
final boolean producePartialOutputWhileProcessing = getProducePartialOutputWhileProcessing();
// If we have chosen to not output anything until processing finishes, we will use a buffer
final Writer templateWriter =
(producePartialOutputWhileProcessing? response.getWriter() : new FastStringWriter(1024));
viewTemplateEngine.process(templateName, processMarkupSelectors, context, templateWriter);
// If a buffer was used, write it to the web server's output buffers all at once
if (!producePartialOutputWhileProcessing) {
response.getWriter().write(templateWriter.toString());
response.getWriter().flush();
}
}
}
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