/*
* Copyright 2002-2008 the original author or authors.
*
* 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.springframework.web.servlet;
import java.io.IOException;
import java.util.Map;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.web.util.NestedServletException;
/**
* ViewRendererServlet is a bridge servlet, mainly for the Portlet MVC support.
*
* <p>For usage with Portlets, this Servlet is necessary to force the portlet container
* to convert the PortletRequest to a ServletRequest, which it has to do when
* including a resource via the PortletRequestDispatcher. This allows for reuse
* of the entire Servlet-based View support even in a Portlet environment.
*
* <p>The actual mapping of the bridge servlet is configurable in the DispatcherPortlet,
* via a "viewRendererUrl" property. The default is "/WEB-INF/servlet/view", which is
* just available for internal resource dispatching.
*
* @author William G. Thompson, Jr.
* @author John A. Lewis
* @author Juergen Hoeller
* @since 2.0
*/
public class ViewRendererServlet extends HttpServlet {
/**
* Request attribute to hold current web application context.
* Otherwise only the global web app context is obtainable by tags etc.
* @see org.springframework.web.servlet.support.RequestContextUtils#getWebApplicationContext
*/
public static final String WEB_APPLICATION_CONTEXT_ATTRIBUTE = DispatcherServlet.WEB_APPLICATION_CONTEXT_ATTRIBUTE;
/** Name of request attribute that holds the View object */
public static final String VIEW_ATTRIBUTE = ViewRendererServlet.class.getName() + ".VIEW";
/** Name of request attribute that holds the model Map */
public static final String MODEL_ATTRIBUTE = ViewRendererServlet.class.getName() + ".MODEL";
@Override
protected final void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request, response);
}
@Override
protected final void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request, response);
}
/**
* Process this request, handling exceptions.
* The actually event handling is performed by the abstract
* <code>renderView()</code> template method.
* @see #renderView
*/
protected final void processRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
try {
renderView(request, response);
}
catch (ServletException ex) {
throw ex;
}
catch (IOException ex) {
throw ex;
}
catch (Exception ex) {
throw new NestedServletException("View rendering failed", ex);
}
}
/**
* Retrieve the View instance and model Map to render
* and trigger actual rendering.
* @param request current HTTP request
* @param response current HTTP response
* @throws Exception in case of any kind of processing failure
* @see org.springframework.web.servlet.View#render
*/
@SuppressWarnings("unchecked")
protected void renderView(HttpServletRequest request, HttpServletResponse response) throws Exception {
View view = (View) request.getAttribute(VIEW_ATTRIBUTE);
if (view == null) {
throw new ServletException("Could not complete render request: View is null");
}
Map<String, Object> model = (Map<String, Object>) request.getAttribute(MODEL_ATTRIBUTE);
view.render(model, request, response);
}
}
|