/*

  * $Id: VelocityRenderer.java 1306435 2012-03-28 15:39:11Z nlebas $

  *

  * 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.tiles.request.velocity.render;

 import java.io.IOException;

 import org.apache.tiles.request.Request;

 import org.apache.tiles.request.render.CannotRenderException;

 import org.apache.tiles.request.render.Renderer;

 import org.apache.tiles.request.servlet.ServletRequest;

 import org.apache.tiles.request.servlet.ServletUtil;

 import org.apache.velocity.Template;

 import org.apache.velocity.context.Context;

 import org.apache.velocity.tools.view.VelocityView;

 /**

  * Attribute renderer for rendering Velocity templates as attributes. <br>

  * It is available only to Servlet-based environment.<br>

  * It uses {@link VelocityView} to render the response.<br>

  * To initialize it correctly, call {@link #setParameter(String, String)} for

  * all the parameters that you want to set, and then call {@link #commit()}.

  *

  * @version $Rev: 1306435 $ $Date: 2012-03-29 02:39:11 +1100 (Thu, 29 Mar 2012) $

  */

 public class VelocityRenderer implements Renderer {

     /**

      * The VelocityView object to use.

      */

     private VelocityView velocityView;

     /**

      * Constructor.

      *

      * @param velocityView The Velocity view manager.

      */

     public VelocityRenderer(VelocityView velocityView) {

         this.velocityView = velocityView;

     }

     /** {@inheritDoc} */

     @Override

     public void render(String path, Request request) throws IOException {

         if (path == null) {

             throw new CannotRenderException("Cannot dispatch a null path");

         }

         ServletRequest servletRequest = ServletUtil.getServletRequest(request);

         // then get a context

         Context context = velocityView.createContext(servletRequest

                 .getRequest(), servletRequest.getResponse());

         // get the template

         Template template = velocityView.getTemplate((String) path);

         // merge the template and context into the writer

         velocityView.merge(template, context, request.getWriter());

     }

     /** {@inheritDoc} */

     public boolean isRenderable(String path, Request request) {

         return path != null && path.startsWith("/") && path.endsWith(".vm");

     }

 }