/*
* $Id: FreemarkerResult.java 724514 2008-12-08 22:17:52Z musachy $
*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* 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
* "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.apache.struts2.views.freemarker;
import java.io.CharArrayWriter;
import java.io.IOException;
import java.io.Writer;
import java.util.Locale;
import javax.servlet.ServletContext;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.struts2.ServletActionContext;
import org.apache.struts2.dispatcher.StrutsResultSupport;
import org.apache.struts2.views.util.ResourceUtil;
import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.LocaleProvider;
import com.opensymphony.xwork2.inject.Inject;
import com.opensymphony.xwork2.util.ValueStack;
import freemarker.template.Configuration;
import freemarker.template.ObjectWrapper;
import freemarker.template.Template;
import freemarker.template.TemplateException;
import freemarker.template.TemplateExceptionHandler;
import freemarker.template.TemplateModel;
import freemarker.template.TemplateModelException;
/**
* <!-- START SNIPPET: description -->
*
* Renders a view using the Freemarker template engine.
* <p>
* The FreemarkarManager class configures the template loaders so that the
* template location can be either
* </p>
*
* <ul>
*
* <li>relative to the web root folder. eg <code>/WEB-INF/views/home.ftl</code>
* </li>
*
* <li>a classpath resuorce. eg <code>/com/company/web/views/home.ftl</code></li>
*
* </ul>
*
* <!-- END SNIPPET: description -->
*
* <b>This result type takes the following parameters:</b>
*
* <!-- START SNIPPET: params -->
*
* <ul>
*
* <li><b>location (default)</b> - the location of the template to process.</li>
*
* <li><b>parse</b> - true by default. If set to false, the location param will
* not be parsed for Ognl expressions.</li>
*
* <li><b>contentType</b> - defaults to "text/html" unless specified.</li>
*
* <li><b>writeIfCompleted</b> - false by default, write to stream only if there isn't any error
* processing the template. Setting template_exception_handler=rethrow in freemarker.properties
* will have the same effect.</li>
*
* </ul>
*
* <!-- END SNIPPET: params -->
*
* <b>Example:</b>
*
* <pre>
* <!-- START SNIPPET: example -->
*
* <result name="success" type="freemarker">foo.ftl</result>
*
* <!-- END SNIPPET: example -->
* </pre>
*/
public class FreemarkerResult extends StrutsResultSupport {
private static final long serialVersionUID = -3778230771704661631L;
protected ActionInvocation invocation;
protected Configuration configuration;
protected ObjectWrapper wrapper;
protected FreemarkerManager freemarkerManager;
private Writer writer;
private boolean writeIfCompleted = false;
/*
* Struts results are constructed for each result execution
*
* the current context is availible to subclasses via these protected fields
*/
protected String location;
private String pContentType = "text/html";
public FreemarkerResult() {
super();
}
public FreemarkerResult(String location) {
super(location);
}
@Inject
public void setFreemarkerManager(FreemarkerManager mgr) {
this.freemarkerManager = mgr;
}
public void setContentType(String aContentType) {
pContentType = aContentType;
}
/**
* allow parameterization of the contentType
* the default being text/html
*/
public String getContentType() {
return pContentType;
}
/**
* Execute this result, using the specified template locationArg.
* <p/>
* The template locationArg has already been interoplated for any variable substitutions
* <p/>
* this method obtains the freemarker configuration and the object wrapper from the provided hooks.
* It them implements the template processing workflow by calling the hooks for
* preTemplateProcess and postTemplateProcess
*/
public void doExecute(String locationArg, ActionInvocation invocation) throws IOException, TemplateException {
this.location = locationArg;
this.invocation = invocation;
this.configuration = getConfiguration();
this.wrapper = getObjectWrapper();
if (!locationArg.startsWith("/")) {
ActionContext ctx = invocation.getInvocationContext();
HttpServletRequest req = (HttpServletRequest) ctx.get(ServletActionContext.HTTP_REQUEST);
String base = ResourceUtil.getResourceBase(req);
locationArg = base + "/" + locationArg;
}
Template template = configuration.getTemplate(locationArg, deduceLocale());
TemplateModel model = createModel();
// Give subclasses a chance to hook into preprocessing
if (preTemplateProcess(template, model)) {
try {
// Process the template
Writer writer = getWriter();
if (isWriteIfCompleted() || configuration.getTemplateExceptionHandler() == TemplateExceptionHandler.RETHROW_HANDLER) {
CharArrayWriter charArrayWriter = new CharArrayWriter();
try {
template.process(model, charArrayWriter);
charArrayWriter.flush();
charArrayWriter.writeTo(writer);
} finally {
if (charArrayWriter != null)
charArrayWriter.close();
}
} else {
template.process(model, writer);
}
} finally {
// Give subclasses a chance to hook into postprocessing
postTemplateProcess(template, model);
}
}
}
/**
* This method is called from {@link #doExecute(String, ActionInvocation)} to obtain the
* FreeMarker configuration object that this result will use for template loading. This is a
* hook that allows you to custom-configure the configuration object in a subclass, or to fetch
* it from an IoC container.
* <p/>
* <b>
* The default implementation obtains the configuration from the ConfigurationManager instance.
* </b>
*/
protected Configuration getConfiguration() throws TemplateException {
return freemarkerManager.getConfiguration(ServletActionContext.getServletContext());
}
/**
* This method is called from {@link #doExecute(String, ActionInvocation)} to obtain the
* FreeMarker object wrapper object that this result will use for adapting objects into template
* models. This is a hook that allows you to custom-configure the wrapper object in a subclass.
* <p/>
* <b>
* The default implementation returns {@link Configuration#getObjectWrapper()}
* </b>
*/
protected ObjectWrapper getObjectWrapper() {
return configuration.getObjectWrapper();
}
public void setWriter(Writer writer) {
this.writer = writer;
}
/**
* The default writer writes directly to the response writer.
*/
protected Writer getWriter() throws IOException {
if(writer != null) {
return writer;
}
return ServletActionContext.getResponse().getWriter();
}
/**
* Build the instance of the ScopesHashModel, including JspTagLib support
* <p/>
* Objects added to the model are
* <p/>
* <ul>
* <li>Application - servlet context attributes hash model
* <li>JspTaglibs - jsp tag lib factory model
* <li>Request - request attributes hash model
* <li>Session - session attributes hash model
* <li>request - the HttpServletRequst object for direct access
* <li>response - the HttpServletResponse object for direct access
* <li>stack - the OgnLValueStack instance for direct access
* <li>ognl - the instance of the OgnlTool
* <li>action - the action itself
* <li>exception - optional : the JSP or Servlet exception as per the servlet spec (for JSP Exception pages)
* <li>struts - instance of the StrutsUtil class
* </ul>
*/
protected TemplateModel createModel() throws TemplateModelException {
ServletContext servletContext = ServletActionContext.getServletContext();
HttpServletRequest request = ServletActionContext.getRequest();
HttpServletResponse response = ServletActionContext.getResponse();
ValueStack stack = ServletActionContext.getContext().getValueStack();
Object action = null;
if(invocation!= null ) action = invocation.getAction(); //Added for NullPointException
return freemarkerManager.buildTemplateModel(stack, action, servletContext, request, response, wrapper);
}
/**
* Returns the locale used for the {@link Configuration#getTemplate(String, Locale)} call. The base implementation
* simply returns the locale setting of the action (assuming the action implements {@link LocaleProvider}) or, if
* the action does not the configuration's locale is returned. Override this method to provide different behaviour,
*/
protected Locale deduceLocale() {
if (invocation.getAction() instanceof LocaleProvider) {
return ((LocaleProvider) invocation.getAction()).getLocale();
} else {
return configuration.getLocale();
}
}
/**
* the default implementation of postTemplateProcess applies the contentType parameter
*/
protected void postTemplateProcess(Template template, TemplateModel data) throws IOException {
}
/**
* Called before the execution is passed to template.process().
* This is a generic hook you might use in subclasses to perform a specific
* action before the template is processed. By default does nothing.
* A typical action to perform here is to inject application-specific
* objects into the model root
*
* @return true to process the template, false to suppress template processing.
*/
protected boolean preTemplateProcess(Template template, TemplateModel model) throws IOException {
Object attrContentType = template.getCustomAttribute("content_type");
if (attrContentType != null) {
ServletActionContext.getResponse().setContentType(attrContentType.toString());
} else {
String contentType = getContentType();
if (contentType == null) {
contentType = "text/html";
}
String encoding = template.getEncoding();
if (encoding != null) {
contentType = contentType + "; charset=" + encoding;
}
ServletActionContext.getResponse().setContentType(contentType);
}
return true;
}
/**
* @return true write to the stream only when template processing completed successfully (false by default)
*/
public boolean isWriteIfCompleted() {
return writeIfCompleted;
}
/**
* Writes to the stream only when template processing completed successfully
*/
public void setWriteIfCompleted(boolean writeIfCompleted) {
this.writeIfCompleted = writeIfCompleted;
}
}
|