StrutsVelocityManager.java
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* Licensed to the Apache Software Foundation (ASF) under one
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* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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
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* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
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package org.apache.struts2.views.velocity;
import org.apache.struts2.ObjectFactory;
import org.apache.struts2.inject.Container;
import org.apache.struts2.inject.Inject;
import org.apache.struts2.util.ValueStack;
import jakarta.servlet.ServletContext;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import org.apache.commons.lang3.StringUtils;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.apache.struts2.StrutsConstants;
import org.apache.struts2.StrutsException;
import org.apache.struts2.views.TagLibraryDirectiveProvider;
import org.apache.struts2.views.util.ContextUtil;
import org.apache.velocity.VelocityContext;
import org.apache.velocity.app.Velocity;
import org.apache.velocity.app.VelocityEngine;
import org.apache.velocity.context.Context;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import static java.util.Collections.emptyList;
import static java.util.Objects.requireNonNullElse;
import static java.util.stream.Collectors.joining;
import static java.util.stream.Collectors.toList;
import static org.apache.commons.lang3.StringUtils.isBlank;
import static org.apache.struts2.views.util.ContextUtil.STRUTS;
import static org.apache.velocity.runtime.DeprecatedRuntimeConstants.OLD_CUSTOM_DIRECTIVES;
/**
* Manages the environment for Velocity result types
*
* @since 7.0
*/
public class StrutsVelocityManager implements VelocityManager {
private static final Logger LOG = LogManager.getLogger(StrutsVelocityManager.class);
private ObjectFactory objectFactory;
public static final String DEFAULT_CONFIG_FILE = "velocity.properties";
public static final String KEY_VELOCITY_STRUTS_CONTEXT = ".KEY_velocity.struts2.context";
private VelocityEngine velocityEngine;
private VelocityTools velocityTools;
/**
* Names of contexts that will be chained on every request
*/
private List<String> chainedContextNames = emptyList();
private Properties velocityProperties;
private String customConfigFile;
private List<TagLibraryDirectiveProvider> tagLibraries;
@Inject
public void setObjectFactory(ObjectFactory fac) {
this.objectFactory = fac;
}
@Inject
public void setContainer(Container container) {
this.tagLibraries = container.getInstanceNames(TagLibraryDirectiveProvider.class).stream()
.map(prefix -> container.getInstance(TagLibraryDirectiveProvider.class, prefix)).toList();
}
/**
* @return a reference to the VelocityEngine used by <strong>all</strong> Struts Velocity results except directly
* accessed *.vm pages (unless otherwise configured)
*/
@Override
public VelocityEngine getVelocityEngine() {
return velocityEngine;
}
/**
* This method is responsible for creating the standard VelocityContext used by all Struts Velocity views.
*
* @param stack the current {@link ValueStack}
* @param req the current HttpServletRequest
* @param res the current HttpServletResponse
* @return a new StrutsVelocityContext
*/
@Override
public Context createContext(ValueStack stack, HttpServletRequest req, HttpServletResponse res) {
Context context = null;
if (velocityTools != null) {
context = velocityTools.createContext();
}
if (context == null) {
context = buildContext(stack, req, res);
}
req.setAttribute(KEY_VELOCITY_STRUTS_CONTEXT, context);
return context;
}
protected Context buildContext(ValueStack stack, HttpServletRequest req, HttpServletResponse res) {
List<VelocityContext> chainedContexts = prepareChainedContexts(req, res, stack.getContext());
Context context = new StrutsVelocityContext(chainedContexts, stack);
ContextUtil.getStandardContext(stack, req, res).forEach(context::put);
VelocityStrutsUtil util = new VelocityStrutsUtil(velocityEngine, context, stack, req, res);
context.put(STRUTS, util);
return context;
}
/**
* Constructs contexts for chaining on this request. This method does not perform any initialization of the
* contexts. All that must be done in the context itself.
*
* @param servletRequest the servlet request object
* @param servletResponse the servlet response object
* @param extraContext map with extra context
* @return a List of contexts to chain or an empty list
*/
protected List<VelocityContext> prepareChainedContexts(HttpServletRequest servletRequest,
HttpServletResponse servletResponse,
Map<String, Object> extraContext) {
List<VelocityContext> contextList = new ArrayList<>();
for (String className : chainedContextNames) {
try {
VelocityContext velocityContext = (VelocityContext) objectFactory.buildBean(className, extraContext);
contextList.add(velocityContext);
} catch (Exception e) {
LOG.warn("Unable to instantiate chained VelocityContext {}, skipping", className, e);
}
}
return contextList;
}
/**
* initializes the StrutsVelocityManager. this should be called during the initialization process, say by
* ServletDispatcher. this may be called multiple times safely although calls beyond the first won't do anything
*
* @param context the current servlet context
*/
@Override
public synchronized void init(ServletContext context) {
if (velocityEngine != null) {
return;
}
velocityEngine = newVelocityEngine(context);
if (velocityTools != null) {
velocityTools.init(context, velocityEngine);
}
}
protected Properties loadConfiguration(ServletContext context) {
if (context == null) {
throw new IllegalArgumentException("Error attempting to create a loadConfiguration from a null ServletContext!");
}
Properties properties = new Properties();
applyDefaultConfiguration(context, properties); // Apply defaults before loading user overrides
String defaultUserDirective = properties.getProperty("userdirective");
applyUserConfiguration(context, properties);
if (velocityProperties != null) { // Apply additional overriding properties if any
velocityProperties.stringPropertyNames().forEach(k -> properties.setProperty(k, velocityProperties.getProperty(k)));
}
String userDirective = properties.getProperty(OLD_CUSTOM_DIRECTIVES);
String newDirective = isBlank(userDirective) ? defaultUserDirective : userDirective.strip() + "," + defaultUserDirective;
properties.setProperty(OLD_CUSTOM_DIRECTIVES, newDirective);
if (LOG.isDebugEnabled()) {
LOG.debug("Initializing Velocity with the following properties ...");
properties.stringPropertyNames().forEach(k -> LOG.debug(" '{}' = '{}'", k, properties.getProperty(k)));
}
return properties;
}
/**
* Load optional velocity properties using the following loading strategy
* <ul>
* <li>relative to the servlet context path</li>
* <li>relative to the WEB-INF directory</li>
* <li>on the classpath</li>
* </ul>
*/
private void applyUserConfiguration(ServletContext context, Properties properties) {
String configFile = requireNonNullElse(customConfigFile, DEFAULT_CONFIG_FILE).trim();
try {
if (loadFile(properties, context.getRealPath(configFile))) {
return;
}
} catch (IOException e) {
LOG.warn("Unable to load Velocity configuration from servlet context path", e);
}
try {
if (loadFile(properties, context.getRealPath("/WEB-INF/" + configFile))) {
return;
}
} catch (IOException e) {
LOG.warn("Unable to load Velocity configuration from WEB-INF path", e);
}
try {
loadClassPathFile(properties, configFile);
} catch (IOException e) {
LOG.warn("Unable to load Velocity configuration from classpath", e);
}
}
private boolean loadClassPathFile(Properties properties, String configFile) throws IOException {
try (InputStream is = StrutsVelocityManager.class.getClassLoader().getResourceAsStream(configFile)) {
if (is == null) {
return false;
}
properties.load(is);
LOG.info("Initializing Velocity using {} from classpath", configFile);
return true;
}
}
private boolean loadFile(Properties properties, String fileName) throws IOException {
if (fileName == null) {
return false;
}
File file = new File(fileName);
if (!file.isFile()) {
return false;
}
try (InputStream is = new FileInputStream(file)) {
properties.load(is);
LOG.info("Initializing Velocity using {}", file.getCanonicalPath() + " from file system");
return true;
}
}
@Inject(StrutsConstants.STRUTS_VELOCITY_CONFIGFILE)
public void setCustomConfigFile(String customConfigFile) {
this.customConfigFile = customConfigFile;
}
@Inject(StrutsConstants.STRUTS_VELOCITY_TOOLBOXLOCATION)
public void setToolBoxLocation(String toolboxLocation) {
if (!isBlank(toolboxLocation)) {
this.velocityTools = new VelocityTools(toolboxLocation);
}
}
public VelocityTools getVelocityTools() {
return velocityTools;
}
/**
* Allow users to specify via the struts.properties file a set of additional VelocityContexts to chain to the
* StrutsVelocityContext. The intent is to allow these contexts to store helper objects that the ui developer may
* want access to. Examples of reasonable VelocityContexts would be an IoCVelocityContext, a
* SpringReferenceVelocityContext, and a ToolboxVelocityContext
*
* @param contexts comma separated velocity context's
*/
@Inject(StrutsConstants.STRUTS_VELOCITY_CONTEXTS)
public void setChainedContexts(String contexts) {
this.chainedContextNames = Arrays.stream(contexts.split(",")).filter(StringUtils::isNotBlank).collect(toList());
}
/**
* Instantiates a new VelocityEngine.
* <p>
* The following is the default Velocity configuration
* <pre>
* resource.loader = file, class
* file.resource.loader.path = real path of webapp
* class.resource.loader.description = Velocity Classpath Resource Loader
* class.resource.loader.class = org.apache.struts2.views.velocity.StrutsResourceLoader
* </pre>
* This default configuration can be overridden by specifying a struts.velocity.configfile property in the
* struts.properties file. the specified config file will be searched for in the following order:
* <ul>
* <li>relative to the servlet context path</li>
* <li>relative to the WEB-INF directory</li>
* <li>on the classpath</li>
* </ul>
*
* @param context the current ServletContext. may <b>not</b> be null
* @return the new velocity engine
*/
protected VelocityEngine newVelocityEngine(ServletContext context) {
if (context == null) {
throw new IllegalArgumentException("Error attempting to create a new VelocityEngine from a null ServletContext!");
}
VelocityEngine velocityEngine = new VelocityEngine();
velocityEngine.setApplicationAttribute(ServletContext.class.getName(), context); // Required for webapp loader
try {
velocityEngine.init(loadConfiguration(context));
} catch (Exception e) {
throw new StrutsException("Unable to instantiate VelocityEngine!", e);
}
return velocityEngine;
}
/**
* Once we've loaded up the user defined configurations, we will want to apply Struts specification configurations.
* <ul>
* <li>if Velocity.RESOURCE_LOADER has not been defined, then we will use the defaults which is a joined file,
* class loader for unpackaed wars and a straight class loader otherwise</li>
* <li>we need to define the various Struts custom user directives such as #param, #tag, and #bodytag</li>
* </ul>
*
* @param context the servlet context
* @param properties velocity properties
*/
private void applyDefaultConfiguration(ServletContext context, Properties properties) {
LOG.debug("Load a default resource loader definition if there isn't one present.");
if (properties.getProperty(Velocity.RESOURCE_LOADER) == null) {
properties.setProperty(Velocity.RESOURCE_LOADER, "strutsfile, strutsclass");
}
// If there's a "real" path add it for the strutsfile resource loader. If there's no real path, and they haven't
// configured a loader then we change resource loader property to just use the strutsclass loader
String realPath = context.getRealPath("");
if (realPath != null) {
setStrutsFileResourceLoader(properties, realPath);
} else {
clearStrutsFileResourceLoader(properties);
}
setStrutsClasspathResourceLoader(properties);
String directives = tagLibraries.stream().map(TagLibraryDirectiveProvider::getDirectiveClasses)
.flatMap(Collection::stream).map(directive -> directive.getName() + ",").collect(joining());
String userDirective = properties.getProperty(OLD_CUSTOM_DIRECTIVES);
String newDirective = isBlank(userDirective) ? directives : userDirective.strip() + "," + directives;
properties.setProperty(OLD_CUSTOM_DIRECTIVES, newDirective);
}
private void setStrutsFileResourceLoader(Properties properties, String realPath) {
properties.setProperty("strutsfile.resource.loader.description", "Velocity File Resource Loader");
properties.setProperty("strutsfile.resource.loader.class", "org.apache.velocity.runtime.resource.loader.FileResourceLoader");
properties.setProperty("strutsfile.resource.loader.path", realPath);
properties.setProperty("strutsfile.resource.loader.modificationCheckInterval", "2");
properties.setProperty("strutsfile.resource.loader.cache", "true");
}
private void clearStrutsFileResourceLoader(Properties properties) {
String prop = properties.getProperty(Velocity.RESOURCE_LOADER)
.replace("strutsfile,", "")
.replace(", strutsfile", "")
.replace("strutsfile", "");
properties.setProperty(Velocity.RESOURCE_LOADER, prop);
}
/**
* Refactored the Velocity templates for the Struts taglib into the classpath from the web path. This will
* enable Struts projects to have access to the templates by simply including the Struts jar file.
* Unfortunately, there does not appear to be a macro for the class loader keywords
*/
private void setStrutsClasspathResourceLoader(Properties properties) {
properties.setProperty("strutsclass.resource.loader.description", "Velocity Classpath Resource Loader");
properties.setProperty("strutsclass.resource.loader.class", "org.apache.struts2.views.velocity.StrutsResourceLoader");
properties.setProperty("strutsclass.resource.loader.modificationCheckInterval", "2");
properties.setProperty("strutsclass.resource.loader.cache", "true");
}
/**
* @return the velocityProperties
*/
public Properties getVelocityProperties() {
return velocityProperties;
}
/**
* @param velocityProperties the velocityProperties to set
*/
public void setVelocityProperties(Properties velocityProperties) {
this.velocityProperties = velocityProperties;
}
}