org.springframework.ui.freemarker.FreeMarkerConfigurationFactory Maven / Gradle / Ivy
/*
* Copyright 2002-2017 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
*
* https://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.ui.freemarker;
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import freemarker.cache.FileTemplateLoader;
import freemarker.cache.MultiTemplateLoader;
import freemarker.cache.TemplateLoader;
import freemarker.template.Configuration;
import freemarker.template.SimpleHash;
import freemarker.template.TemplateException;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.core.io.DefaultResourceLoader;
import org.springframework.core.io.Resource;
import org.springframework.core.io.ResourceLoader;
import org.springframework.core.io.support.PropertiesLoaderUtils;
import org.springframework.util.CollectionUtils;
/**
* Factory that configures a FreeMarker Configuration. Can be used standalone, but
* typically you will either use FreeMarkerConfigurationFactoryBean for preparing a
* Configuration as bean reference, or FreeMarkerConfigurer for web views.
*
* The optional "configLocation" property sets the location of a FreeMarker
* properties file, within the current application. FreeMarker properties can be
* overridden via "freemarkerSettings". All of these properties will be set by
* calling FreeMarker's {@code Configuration.setSettings()} method and are
* subject to constraints set by FreeMarker.
*
*
The "freemarkerVariables" property can be used to specify a Map of
* shared variables that will be applied to the Configuration via the
* {@code setAllSharedVariables()} method. Like {@code setSettings()},
* these entries are subject to FreeMarker constraints.
*
*
The simplest way to use this class is to specify a "templateLoaderPath";
* FreeMarker does not need any further configuration then.
*
*
Note: Spring's FreeMarker support requires FreeMarker 2.3 or higher.
*
* @author Darren Davison
* @author Juergen Hoeller
* @since 03.03.2004
* @see #setConfigLocation
* @see #setFreemarkerSettings
* @see #setFreemarkerVariables
* @see #setTemplateLoaderPath
* @see #createConfiguration
* @see FreeMarkerConfigurationFactoryBean
* @see org.springframework.web.servlet.view.freemarker.FreeMarkerConfigurer
* @see freemarker.template.Configuration
*/
public class FreeMarkerConfigurationFactory {
protected final Log logger = LogFactory.getLog(getClass());
private Resource configLocation;
private Properties freemarkerSettings;
private Map freemarkerVariables;
private String defaultEncoding;
private final List templateLoaders = new ArrayList();
private List preTemplateLoaders;
private List postTemplateLoaders;
private String[] templateLoaderPaths;
private ResourceLoader resourceLoader = new DefaultResourceLoader();
private boolean preferFileSystemAccess = true;
/**
* Set the location of the FreeMarker config file.
* Alternatively, you can specify all setting locally.
* @see #setFreemarkerSettings
* @see #setTemplateLoaderPath
*/
public void setConfigLocation(Resource resource) {
configLocation = resource;
}
/**
* Set properties that contain well-known FreeMarker keys which will be
* passed to FreeMarker's {@code Configuration.setSettings} method.
* @see freemarker.template.Configuration#setSettings
*/
public void setFreemarkerSettings(Properties settings) {
this.freemarkerSettings = settings;
}
/**
* Set a Map that contains well-known FreeMarker objects which will be passed
* to FreeMarker's {@code Configuration.setAllSharedVariables()} method.
* @see freemarker.template.Configuration#setAllSharedVariables
*/
public void setFreemarkerVariables(Map variables) {
this.freemarkerVariables = variables;
}
/**
* Set the default encoding for the FreeMarker configuration.
* If not specified, FreeMarker will use the platform file encoding.
* Used for template rendering unless there is an explicit encoding specified
* for the rendering process (for example, on Spring's FreeMarkerView).
* @see freemarker.template.Configuration#setDefaultEncoding
* @see org.springframework.web.servlet.view.freemarker.FreeMarkerView#setEncoding
*/
public void setDefaultEncoding(String defaultEncoding) {
this.defaultEncoding = defaultEncoding;
}
/**
* Set a List of {@code TemplateLoader}s that will be used to search
* for templates. For example, one or more custom loaders such as database
* loaders could be configured and injected here.
*
The {@link TemplateLoader TemplateLoaders} specified here will be
* registered before the default template loaders that this factory
* registers (such as loaders for specified "templateLoaderPaths" or any
* loaders registered in {@link #postProcessTemplateLoaders}).
* @see #setTemplateLoaderPaths
* @see #postProcessTemplateLoaders
*/
public void setPreTemplateLoaders(TemplateLoader... preTemplateLoaders) {
this.preTemplateLoaders = Arrays.asList(preTemplateLoaders);
}
/**
* Set a List of {@code TemplateLoader}s that will be used to search
* for templates. For example, one or more custom loaders such as database
* loaders can be configured.
*
The {@link TemplateLoader TemplateLoaders} specified here will be
* registered after the default template loaders that this factory
* registers (such as loaders for specified "templateLoaderPaths" or any
* loaders registered in {@link #postProcessTemplateLoaders}).
* @see #setTemplateLoaderPaths
* @see #postProcessTemplateLoaders
*/
public void setPostTemplateLoaders(TemplateLoader... postTemplateLoaders) {
this.postTemplateLoaders = Arrays.asList(postTemplateLoaders);
}
/**
* Set the Freemarker template loader path via a Spring resource location.
* See the "templateLoaderPaths" property for details on path handling.
* @see #setTemplateLoaderPaths
*/
public void setTemplateLoaderPath(String templateLoaderPath) {
this.templateLoaderPaths = new String[] {templateLoaderPath};
}
/**
* Set multiple Freemarker template loader paths via Spring resource locations.
*
When populated via a String, standard URLs like "file:" and "classpath:"
* pseudo URLs are supported, as understood by ResourceEditor. Allows for
* relative paths when running in an ApplicationContext.
*
Will define a path for the default FreeMarker template loader.
* If a specified resource cannot be resolved to a {@code java.io.File},
* a generic SpringTemplateLoader will be used, without modification detection.
*
To enforce the use of SpringTemplateLoader, i.e. to not resolve a path
* as file system resource in any case, turn off the "preferFileSystemAccess"
* flag. See the latter's javadoc for details.
*
If you wish to specify your own list of TemplateLoaders, do not set this
* property and instead use {@code setTemplateLoaders(List templateLoaders)}
* @see org.springframework.core.io.ResourceEditor
* @see org.springframework.context.ApplicationContext#getResource
* @see freemarker.template.Configuration#setDirectoryForTemplateLoading
* @see SpringTemplateLoader
*/
public void setTemplateLoaderPaths(String... templateLoaderPaths) {
this.templateLoaderPaths = templateLoaderPaths;
}
/**
* Set the Spring ResourceLoader to use for loading FreeMarker template files.
* The default is DefaultResourceLoader. Will get overridden by the
* ApplicationContext if running in a context.
* @see org.springframework.core.io.DefaultResourceLoader
*/
public void setResourceLoader(ResourceLoader resourceLoader) {
this.resourceLoader = resourceLoader;
}
/**
* Return the Spring ResourceLoader to use for loading FreeMarker template files.
*/
protected ResourceLoader getResourceLoader() {
return this.resourceLoader;
}
/**
* Set whether to prefer file system access for template loading.
* File system access enables hot detection of template changes.
*
If this is enabled, FreeMarkerConfigurationFactory will try to resolve
* the specified "templateLoaderPath" as file system resource (which will work
* for expanded class path resources and ServletContext resources too).
*
Default is "true". Turn this off to always load via SpringTemplateLoader
* (i.e. as stream, without hot detection of template changes), which might
* be necessary if some of your templates reside in an expanded classes
* directory while others reside in jar files.
* @see #setTemplateLoaderPath
*/
public void setPreferFileSystemAccess(boolean preferFileSystemAccess) {
this.preferFileSystemAccess = preferFileSystemAccess;
}
/**
* Return whether to prefer file system access for template loading.
*/
protected boolean isPreferFileSystemAccess() {
return this.preferFileSystemAccess;
}
/**
* Prepare the FreeMarker Configuration and return it.
* @return the FreeMarker Configuration object
* @throws IOException if the config file wasn't found
* @throws TemplateException on FreeMarker initialization failure
*/
public Configuration createConfiguration() throws IOException, TemplateException {
Configuration config = newConfiguration();
Properties props = new Properties();
// Load config file if specified.
if (this.configLocation != null) {
if (logger.isInfoEnabled()) {
logger.info("Loading FreeMarker configuration from " + this.configLocation);
}
PropertiesLoaderUtils.fillProperties(props, this.configLocation);
}
// Merge local properties if specified.
if (this.freemarkerSettings != null) {
props.putAll(this.freemarkerSettings);
}
// FreeMarker will only accept known keys in its setSettings and
// setAllSharedVariables methods.
if (!props.isEmpty()) {
config.setSettings(props);
}
if (!CollectionUtils.isEmpty(this.freemarkerVariables)) {
config.setAllSharedVariables(new SimpleHash(this.freemarkerVariables, config.getObjectWrapper()));
}
if (this.defaultEncoding != null) {
config.setDefaultEncoding(this.defaultEncoding);
}
List templateLoaders = new LinkedList(this.templateLoaders);
// Register template loaders that are supposed to kick in early.
if (this.preTemplateLoaders != null) {
templateLoaders.addAll(this.preTemplateLoaders);
}
// Register default template loaders.
if (this.templateLoaderPaths != null) {
for (String path : this.templateLoaderPaths) {
templateLoaders.add(getTemplateLoaderForPath(path));
}
}
postProcessTemplateLoaders(templateLoaders);
// Register template loaders that are supposed to kick in late.
if (this.postTemplateLoaders != null) {
templateLoaders.addAll(this.postTemplateLoaders);
}
TemplateLoader loader = getAggregateTemplateLoader(templateLoaders);
if (loader != null) {
config.setTemplateLoader(loader);
}
postProcessConfiguration(config);
return config;
}
/**
* Return a new Configuration object. Subclasses can override this for custom
* initialization (e.g. specifying a FreeMarker compatibility level which is a
* new feature in FreeMarker 2.3.21), or for using a mock object for testing.
* Called by {@code createConfiguration()}.
* @return the Configuration object
* @throws IOException if a config file wasn't found
* @throws TemplateException on FreeMarker initialization failure
* @see #createConfiguration()
*/
protected Configuration newConfiguration() throws IOException, TemplateException {
return new Configuration(Configuration.DEFAULT_INCOMPATIBLE_IMPROVEMENTS);
}
/**
* Determine a FreeMarker TemplateLoader for the given path.
*
Default implementation creates either a FileTemplateLoader or
* a SpringTemplateLoader.
* @param templateLoaderPath the path to load templates from
* @return an appropriate TemplateLoader
* @see freemarker.cache.FileTemplateLoader
* @see SpringTemplateLoader
*/
protected TemplateLoader getTemplateLoaderForPath(String templateLoaderPath) {
if (isPreferFileSystemAccess()) {
// Try to load via the file system, fall back to SpringTemplateLoader
// (for hot detection of template changes, if possible).
try {
Resource path = getResourceLoader().getResource(templateLoaderPath);
File file = path.getFile(); // will fail if not resolvable in the file system
if (logger.isDebugEnabled()) {
logger.debug(
"Template loader path [" + path + "] resolved to file path [" + file.getAbsolutePath() + "]");
}
return new FileTemplateLoader(file);
}
catch (Exception ex) {
if (logger.isDebugEnabled()) {
logger.debug("Cannot resolve template loader path [" + templateLoaderPath +
"] to [java.io.File]: using SpringTemplateLoader as fallback", ex);
}
return new SpringTemplateLoader(getResourceLoader(), templateLoaderPath);
}
}
else {
// Always load via SpringTemplateLoader (without hot detection of template changes).
logger.debug("File system access not preferred: using SpringTemplateLoader");
return new SpringTemplateLoader(getResourceLoader(), templateLoaderPath);
}
}
/**
* To be overridden by subclasses that want to register custom
* TemplateLoader instances after this factory created its default
* template loaders.
*
Called by {@code createConfiguration()}. Note that specified
* "postTemplateLoaders" will be registered after any loaders
* registered by this callback; as a consequence, they are not
* included in the given List.
* @param templateLoaders the current List of TemplateLoader instances,
* to be modified by a subclass
* @see #createConfiguration()
* @see #setPostTemplateLoaders
*/
protected void postProcessTemplateLoaders(List templateLoaders) {
}
/**
* Return a TemplateLoader based on the given TemplateLoader list.
* If more than one TemplateLoader has been registered, a FreeMarker
* MultiTemplateLoader needs to be created.
* @param templateLoaders the final List of TemplateLoader instances
* @return the aggregate TemplateLoader
*/
protected TemplateLoader getAggregateTemplateLoader(List templateLoaders) {
int loaderCount = templateLoaders.size();
switch (loaderCount) {
case 0:
logger.info("No FreeMarker TemplateLoaders specified");
return null;
case 1:
return templateLoaders.get(0);
default:
TemplateLoader[] loaders = templateLoaders.toArray(new TemplateLoader[loaderCount]);
return new MultiTemplateLoader(loaders);
}
}
/**
* To be overridden by subclasses that want to perform custom
* post-processing of the Configuration object after this factory
* performed its default initialization.
* Called by {@code createConfiguration()}.
* @param config the current Configuration object
* @throws IOException if a config file wasn't found
* @throws TemplateException on FreeMarker initialization failure
* @see #createConfiguration()
*/
protected void postProcessConfiguration(Configuration config) throws IOException, TemplateException {
}
}