/*
* $Id: VelocityResult.java 454565 2006-10-10 00:02:56Z jmitchell $
*
* Copyright 2006 The Apache Software Foundation.
*
* 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.apache.struts2.dispatcher;
import java.io.OutputStreamWriter;
import java.io.Writer;
import javax.servlet.Servlet;
import javax.servlet.ServletContext;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.jsp.JspFactory;
import javax.servlet.jsp.PageContext;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.struts2.ServletActionContext;
import org.apache.struts2.StrutsConstants;
import org.apache.struts2.config.Settings;
import org.apache.struts2.views.JspSupportServlet;
import org.apache.struts2.views.velocity.VelocityManager;
import org.apache.velocity.Template;
import org.apache.velocity.app.VelocityEngine;
import org.apache.velocity.context.Context;
import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.util.ValueStack;
/**
* <!-- START SNIPPET: description -->
*
* Using the Servlet container's {@link JspFactory}, this result mocks a JSP
* execution environment and then displays a Velocity template that will be
* streamed directly to the servlet output.
*
* <!-- END SNIPPET: description -->
* <p/>
* <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>
*
* </ul>
* <p>
* This result follows the same rules from {@link StrutsResultSupport}.
* </p>
*
* <!-- END SNIPPET: params -->
*
* <b>Example:</b>
*
* <pre><!-- START SNIPPET: example -->
* <result name="success" type="velocity">
* <param name="location">foo.vm</param>
* </result>
* <!-- END SNIPPET: example --></pre>
*
*/
public class VelocityResult extends StrutsResultSupport {
private static final long serialVersionUID = 7268830767762559424L;
private static final Log log = LogFactory.getLog(VelocityResult.class);
public VelocityResult() {
super();
}
public VelocityResult(String location) {
super(location);
}
/**
* Creates a Velocity context from the action, loads a Velocity template and executes the
* template. Output is written to the servlet output stream.
*
* @param finalLocation the location of the Velocity template
* @param invocation an encapsulation of the action execution state.
* @throws Exception if an error occurs when creating the Velocity context, loading or executing
* the template or writing output to the servlet response stream.
*/
public void doExecute(String finalLocation, ActionInvocation invocation) throws Exception {
ValueStack stack = ActionContext.getContext().getValueStack();
HttpServletRequest request = ServletActionContext.getRequest();
HttpServletResponse response = ServletActionContext.getResponse();
JspFactory jspFactory = null;
ServletContext servletContext = ServletActionContext.getServletContext();
Servlet servlet = JspSupportServlet.jspSupportServlet;
VelocityManager.getInstance().init(servletContext);
boolean usedJspFactory = false;
PageContext pageContext = (PageContext) ActionContext.getContext().get(ServletActionContext.PAGE_CONTEXT);
if (pageContext == null && servlet != null) {
jspFactory = JspFactory.getDefaultFactory();
pageContext = jspFactory.getPageContext(servlet, request, response, null, true, 8192, true);
ActionContext.getContext().put(ServletActionContext.PAGE_CONTEXT, pageContext);
usedJspFactory = true;
}
try {
String encoding = getEncoding(finalLocation);
String contentType = getContentType(finalLocation);
if (encoding != null) {
contentType = contentType + ";charset=" + encoding;
}
VelocityManager velocityManager = VelocityManager.getInstance();
Template t = getTemplate(stack, velocityManager.getVelocityEngine(), invocation, finalLocation, encoding);
Context context = createContext(velocityManager, stack, request, response, finalLocation);
Writer writer = new OutputStreamWriter(response.getOutputStream(), encoding);
response.setContentType(contentType);
t.merge(context, writer);
// always flush the writer (we used to only flush it if this was a jspWriter, but someone asked
// to do it all the time (WW-829). Since Velocity support is being deprecated, we'll oblige :)
writer.flush();
} catch (Exception e) {
log.error("Unable to render Velocity Template, '" + finalLocation + "'", e);
throw e;
} finally {
if (usedJspFactory) {
jspFactory.releasePageContext(pageContext);
}
}
return;
}
/**
* Retrieve the content type for this template.
* <p/>
* People can override this method if they want to provide specific content types for specific templates (eg text/xml).
*
* @return The content type associated with this template (default "text/html")
*/
protected String getContentType(String templateLocation) {
return "text/html";
}
/**
* Retrieve the encoding for this template.
* <p/>
* People can override this method if they want to provide specific encodings for specific templates.
*
* @return The encoding associated with this template (defaults to the value of 'struts.i18n.encoding' property)
*/
protected String getEncoding(String templateLocation) {
String encoding = (String) Settings.get(StrutsConstants.STRUTS_I18N_ENCODING);
if (encoding == null) {
encoding = System.getProperty("file.encoding");
}
if (encoding == null) {
encoding = "UTF-8";
}
return encoding;
}
/**
* Given a value stack, a Velocity engine, and an action invocation, this method returns the appropriate
* Velocity template to render.
*
* @param stack the value stack to resolve the location again (when parse equals true)
* @param velocity the velocity engine to process the request against
* @param invocation an encapsulation of the action execution state.
* @param location the location of the template
* @param encoding the charset encoding of the template
* @return the template to render
* @throws Exception when the requested template could not be found
*/
protected Template getTemplate(ValueStack stack, VelocityEngine velocity, ActionInvocation invocation, String location, String encoding) throws Exception {
if (!location.startsWith("/")) {
location = invocation.getProxy().getNamespace() + "/" + location;
}
Template template = velocity.getTemplate(location, encoding);
return template;
}
/**
* Creates the VelocityContext that we'll use to render this page.
*
* @param velocityManager a reference to the velocityManager to use
* @param stack the value stack to resolve the location against (when parse equals true)
* @param location the name of the template that is being used
* @return the a minted Velocity context.
*/
protected Context createContext(VelocityManager velocityManager, ValueStack stack, HttpServletRequest request, HttpServletResponse response, String location) {
return velocityManager.createContext(stack, request, response);
}
}