org.springframework.web.servlet.view.freemarker.FreeMarkerView Maven / Gradle / Ivy
/*
* Copyright 2002-2005 the original author or authors.
*
* 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.springframework.web.servlet.view.freemarker;
import java.io.IOException;
import java.util.Locale;
import java.util.Map;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import freemarker.core.ParseException;
import freemarker.template.Configuration;
import freemarker.template.Template;
import freemarker.template.TemplateException;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanFactoryUtils;
import org.springframework.beans.factory.NoSuchBeanDefinitionException;
import org.springframework.context.ApplicationContextException;
import org.springframework.web.servlet.support.RequestContextUtils;
import org.springframework.web.servlet.view.AbstractTemplateView;
/**
* View using the FreeMarker template engine.
*
* Exposes the following JavaBean properties:
*
* - url: the location of the FreeMarker template to be wrapped,
* relative to the FreeMarker template context (directory).
*
- encoding (optional, default is determined by FreeMarker configuration):
* the encoding of the FreeMarker template file
*
*
* Depends on a single FreeMarkerConfig object such as FreeMarkerConfigurer
* being accessible in the current web application context, with any bean name.
* Alternatively, you can set the FreeMarker Configuration object as bean property.
*
*
Note: Spring's FreeMarker support requires FreeMarker 2.3 or higher.
*
* @author Darren Davison
* @author Juergen Hoeller
* @since 3/3/2004
* @see #setUrl
* @see #setExposeSpringMacroHelpers
* @see #setEncoding
* @see #setConfiguration
* @see FreeMarkerConfig
* @see FreeMarkerConfigurer
*/
public class FreeMarkerView extends AbstractTemplateView {
private String encoding;
private Configuration configuration;
/**
* Set the encoding of the FreeMarker template file. Default is determined
* by the FreeMarker Configuration: "ISO-8859-1" if not specified otherwise.
*
Specify the encoding in the FreeMarker Configuration rather than per
* template if all your templates share a common encoding.
*/
public void setEncoding(String encoding) {
this.encoding = encoding;
}
/**
* Return the encoding for the FreeMarker template.
*/
protected String getEncoding() {
return encoding;
}
/**
* Set the FreeMarker Configuration to be used by this view.
* If this is not set, the default lookup will occur: A single FreeMarkerConfig
* is expected in the current web application context, with any bean name.
* @see FreeMarkerConfig
*/
public void setConfiguration(Configuration configration) {
this.configuration = configration;
}
/**
* Return the FreeMarker configuration used by this view.
*/
protected Configuration getConfiguration() {
return configuration;
}
/**
* Invoked on startup. Looks for a single FreeMarkerConfig bean to
* find the relevant Configuration for this factory.
*
Checks that the template for the default Locale can be found:
* FreeMarker will check non-Locale-specific templates if a
* locale-specific one is not found.
* @see freemarker.cache.TemplateCache#getTemplate
*/
protected void initApplicationContext() throws BeansException {
super.initApplicationContext();
if (getConfiguration() == null) {
// No explicit Configuration instance: try to autodetect one.
setConfiguration(autodetectConfiguration());
}
checkTemplate();
}
/**
* Autodetect a FreeMarker Configuration object via the ApplicationContext.
* Called if no explicit Configuration instance has been specified.
* @return the Configuration instance to use for FreeMarkerViews
* @throws BeansException if no Configuration instance could be found
* @see #getApplicationContext
* @see #setConfiguration
*/
protected Configuration autodetectConfiguration() throws BeansException {
try {
FreeMarkerConfig freemarkerConfig = (FreeMarkerConfig)
BeanFactoryUtils.beanOfTypeIncludingAncestors(
getApplicationContext(), FreeMarkerConfig.class, true, false);
return freemarkerConfig.getConfiguration();
}
catch (NoSuchBeanDefinitionException ex) {
throw new ApplicationContextException(
"Must define a single FreeMarkerConfig bean in this web application context " +
"(may be inherited): FreeMarkerConfigurer is the usual implementation. " +
"This bean may be given any name.", ex);
}
}
/**
* Check that the FreeMarker template used for this view exists and is valid.
*
Can be overridden to customize the behavior, for example in case of
* multiple templates to be rendered into a single view.
* @throws ApplicationContextException if the template cannot be found or is invalid
*/
protected void checkTemplate() throws ApplicationContextException {
try {
// Check that we can get the template, even if we might subsequently get it again.
getTemplate(getConfiguration().getLocale());
}
catch (ParseException ex) {
throw new ApplicationContextException(
"Failed to parse FreeMarker template for URL [" + getUrl() + "]", ex);
}
catch (IOException ex) {
throw new ApplicationContextException(
"Could not load FreeMarker template for URL [" + getUrl() + "]", ex);
}
}
/**
* Process the model map by merging it with the FreeMarker template.
* Output is directed to the servlet response.
*
This method can be overridden if custom behavior is needed.
*/
protected void renderMergedTemplateModel(
Map model, HttpServletRequest request, HttpServletResponse response) throws Exception {
response.setContentType(getContentType());
exposeHelpers(model, request);
doRender(model, request, response);
}
/**
* Expose helpers unique to each rendering operation. This is necessary so that
* different rendering operations can't overwrite each other's formats etc.
*
Called by renderMergedTemplateModel. The default implementation
* is empty. This method can be overridden to add custom helpers to the model.
* @param model The model that will be passed to the template at merge time
* @param request current HTTP request
* @throws Exception if there's a fatal error while we're adding information to the context
* @see #renderMergedTemplateModel
*/
protected void exposeHelpers(Map model, HttpServletRequest request) throws Exception {
}
/**
* Render the FreeMarker view to the given response, using the given model
* map which contains the complete template model to use.
*
The default implementation renders the template specified by the "url"
* bean property, retrieved via getTemplate. It delegates to the
* processTemplate method to merge the template instance with
* the given template model.
*
Can be overridden to customize the behavior, for example to render
* multiple templates into a single view.
* @param model the template model to use for rendering
* @param request current HTTP request
* @param response servlet response (use this to get the OutputStream or Writer)
* @throws IOException if the template file could not be retrieved
* @throws Exception if rendering failed
* @see #setUrl
* @see org.springframework.web.servlet.support.RequestContextUtils#getLocale
* @see #getTemplate(java.util.Locale)
* @see #processTemplate
*/
protected void doRender(Map model, HttpServletRequest request, HttpServletResponse response) throws Exception {
if (logger.isDebugEnabled()) {
logger.debug("Rendering FreeMarker template [" + getUrl() + "] in FreeMarkerView '" + getBeanName() + "'");
}
// Grab the locale-specific version of the template.
Locale locale = RequestContextUtils.getLocale(request);
processTemplate(getTemplate(locale), model, response);
}
/**
* Retrieve the FreeMarker template for the given locale,
* to be rendering by this view.
*
By default, the template specified by the "url" bean property
* will be retrieved.
* @param locale the current locale
* @return the FreeMarker template to render
* @throws IOException if the template file could not be retrieved
* @see #setUrl
* @see #getTemplate(String, java.util.Locale)
*/
protected Template getTemplate(Locale locale) throws IOException {
return getTemplate(getUrl(), locale);
}
/**
* Retrieve the FreeMarker template specified by the given name,
* using the encoding specified by the "encoding" bean property.
*
Can be called by subclasses to retrieve a specific template,
* for example to render multiple templates into a single view.
* @param name the file name of the desired template
* @param locale the current locale
* @return the FreeMarker template
* @throws IOException if the template file could not be retrieved
*/
protected Template getTemplate(String name, Locale locale) throws IOException {
return (getEncoding() != null ?
getConfiguration().getTemplate(name, locale, getEncoding()) :
getConfiguration().getTemplate(name, locale));
}
/**
* Process the FreeMarker template to the servlet response.
*
Can be overridden to customize the behavior.
* @param template the template to process
* @param model the model for the template
* @param response servlet response (use this to get the OutputStream or Writer)
* @throws IOException if the template file could not be retrieved
* @throws TemplateException if thrown by FreeMarker
* @see freemarker.template.Template#process(Object, java.io.Writer)
*/
protected void processTemplate(Template template, Map model, HttpServletResponse response)
throws IOException, TemplateException {
template.process(model, response.getWriter());
}
}