VelocityResult.java
/*
* 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.velocity.result;
import org.apache.struts2.ActionContext;
import org.apache.struts2.ActionInvocation;
import org.apache.struts2.inject.Inject;
import org.apache.struts2.util.ValueStack;
import jakarta.servlet.Servlet;
import jakarta.servlet.ServletContext;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import jakarta.servlet.jsp.JspFactory;
import jakarta.servlet.jsp.PageContext;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.apache.struts2.ServletActionContext;
import org.apache.struts2.StrutsConstants;
import org.apache.struts2.result.StrutsResultSupport;
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 java.io.OutputStreamWriter;
import java.io.Writer;
/**
* <!-- 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>
* </p>
* <!-- 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 -->
* <p>
* <b>Example:</b>
* </p>
* <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 Logger LOG = LogManager.getLogger(VelocityResult.class);
private String defaultEncoding;
private transient VelocityManager velocityManager;
private JspFactory jspFactory = JspFactory.getDefaultFactory();
public VelocityResult() {
super();
}
public VelocityResult(String location) {
super(location);
}
@Inject(StrutsConstants.STRUTS_I18N_ENCODING)
public void setDefaultEncoding(String val) {
defaultEncoding = val;
}
@Inject
public void setVelocityManager(VelocityManager mgr) {
this.velocityManager = mgr;
}
/**
* 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();
ServletContext servletContext = ServletActionContext.getServletContext();
Servlet servlet = JspSupportServlet.jspSupportServlet;
velocityManager.init(servletContext);
boolean usedJspFactory = false;
PageContext pageContext = (PageContext) ActionContext.getContext().getPageContext();
if (pageContext == null && servlet != null) {
pageContext = jspFactory.getPageContext(servlet, request, response, null, true, 8192, true);
ActionContext.getContext().withPageContext(pageContext);
usedJspFactory = true;
}
try {
String encoding = getEncoding(finalLocation);
String contentType = getContentType(finalLocation);
if (encoding != null) {
contentType = contentType + ";charset=" + encoding;
}
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);
}
}
}
/**
* 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).
* </p>
*
* @param templateLocation location of template
* @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.
* </p>
*
* @param templateLocation location of template
* @return The encoding associated with this template (defaults to the value of 'struts.i18n.encoding' property)
*/
protected String getEncoding(String templateLocation) {
String encoding = defaultEncoding;
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 request the servlet request
* @param response the servlet response
* @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);
}
}