001/* 002 * Copyright 2002-2015 the original author or authors. 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); 005 * you may not use this file except in compliance with the License. 006 * You may obtain a copy of the License at 007 * 008 * https://www.apache.org/licenses/LICENSE-2.0 009 * 010 * Unless required by applicable law or agreed to in writing, software 011 * distributed under the License is distributed on an "AS IS" BASIS, 012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 013 * See the License for the specific language governing permissions and 014 * limitations under the License. 015 */ 016 017package org.springframework.web.servlet; 018 019import java.io.IOException; 020import java.util.Map; 021import javax.servlet.ServletException; 022import javax.servlet.http.HttpServlet; 023import javax.servlet.http.HttpServletRequest; 024import javax.servlet.http.HttpServletResponse; 025 026import org.springframework.web.util.NestedServletException; 027 028/** 029 * ViewRendererServlet is a bridge servlet, mainly for the Portlet MVC support. 030 * 031 * <p>For usage with Portlets, this Servlet is necessary to force the portlet container 032 * to convert the PortletRequest to a ServletRequest, which it has to do when 033 * including a resource via the PortletRequestDispatcher. This allows for reuse 034 * of the entire Servlet-based View support even in a Portlet environment. 035 * 036 * <p>The actual mapping of the bridge servlet is configurable in the DispatcherPortlet, 037 * via a "viewRendererUrl" property. The default is "/WEB-INF/servlet/view", which is 038 * just available for internal resource dispatching. 039 * 040 * @author William G. Thompson, Jr. 041 * @author John A. Lewis 042 * @author Juergen Hoeller 043 * @since 2.0 044 */ 045@SuppressWarnings("serial") 046public class ViewRendererServlet extends HttpServlet { 047 048 /** 049 * Request attribute to hold current web application context. 050 * Otherwise only the global web app context is obtainable by tags etc. 051 * @see org.springframework.web.servlet.support.RequestContextUtils#findWebApplicationContext 052 */ 053 public static final String WEB_APPLICATION_CONTEXT_ATTRIBUTE = DispatcherServlet.WEB_APPLICATION_CONTEXT_ATTRIBUTE; 054 055 /** Name of request attribute that holds the View object */ 056 public static final String VIEW_ATTRIBUTE = ViewRendererServlet.class.getName() + ".VIEW"; 057 058 /** Name of request attribute that holds the model Map */ 059 public static final String MODEL_ATTRIBUTE = ViewRendererServlet.class.getName() + ".MODEL"; 060 061 062 @Override 063 protected final void doGet(HttpServletRequest request, HttpServletResponse response) 064 throws ServletException, IOException { 065 066 processRequest(request, response); 067 } 068 069 @Override 070 protected final void doPost(HttpServletRequest request, HttpServletResponse response) 071 throws ServletException, IOException { 072 073 processRequest(request, response); 074 } 075 076 /** 077 * Process this request, handling exceptions. 078 * The actually event handling is performed by the abstract 079 * {@code renderView()} template method. 080 * @see #renderView 081 */ 082 protected final void processRequest(HttpServletRequest request, HttpServletResponse response) 083 throws ServletException, IOException { 084 085 try { 086 renderView(request, response); 087 } 088 catch (ServletException ex) { 089 throw ex; 090 } 091 catch (IOException ex) { 092 throw ex; 093 } 094 catch (Exception ex) { 095 throw new NestedServletException("View rendering failed", ex); 096 } 097 } 098 099 /** 100 * Retrieve the View instance and model Map to render 101 * and trigger actual rendering. 102 * @param request current HTTP request 103 * @param response current HTTP response 104 * @throws Exception in case of any kind of processing failure 105 * @see org.springframework.web.servlet.View#render 106 */ 107 @SuppressWarnings("unchecked") 108 protected void renderView(HttpServletRequest request, HttpServletResponse response) throws Exception { 109 View view = (View) request.getAttribute(VIEW_ATTRIBUTE); 110 if (view == null) { 111 throw new ServletException("Could not complete render request: View is null"); 112 } 113 Map<String, Object> model = (Map<String, Object>) request.getAttribute(MODEL_ATTRIBUTE); 114 view.render(model, request, response); 115 } 116 117}