001/* 002 * Copyright 2002-2014 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.view.feed; 018 019import java.io.OutputStreamWriter; 020import java.util.Map; 021import javax.servlet.ServletOutputStream; 022import javax.servlet.http.HttpServletRequest; 023import javax.servlet.http.HttpServletResponse; 024 025import com.rometools.rome.feed.WireFeed; 026import com.rometools.rome.io.WireFeedOutput; 027 028import org.springframework.util.StringUtils; 029import org.springframework.web.servlet.view.AbstractView; 030 031/** 032 * Abstract base class for Atom and RSS Feed views, using the 033 * <a href="https://github.com/rometools/rome">ROME</a> package. 034 * 035 * <p>><b>NOTE: As of Spring 4.1, this is based on the {@code com.rometools} 036 * variant of ROME, version 1.5. Please upgrade your build dependency.</b> 037 * 038 * <p>Application-specific view classes will typically extend from either 039 * {@link AbstractRssFeedView} or {@link AbstractAtomFeedView} instead of from this class. 040 * 041 * <p>Thanks to Jettro Coenradie and Sergio Bossa for the original feed view prototype! 042 * 043 * @author Arjen Poutsma 044 * @author Juergen Hoeller 045 * @since 3.0 046 * @see AbstractRssFeedView 047 * @see AbstractAtomFeedView 048 */ 049public abstract class AbstractFeedView<T extends WireFeed> extends AbstractView { 050 051 @Override 052 protected final void renderMergedOutputModel( 053 Map<String, Object> model, HttpServletRequest request, HttpServletResponse response) 054 throws Exception { 055 056 T wireFeed = newFeed(); 057 buildFeedMetadata(model, wireFeed, request); 058 buildFeedEntries(model, wireFeed, request, response); 059 060 setResponseContentType(request, response); 061 if (!StringUtils.hasText(wireFeed.getEncoding())) { 062 wireFeed.setEncoding("UTF-8"); 063 } 064 065 WireFeedOutput feedOutput = new WireFeedOutput(); 066 ServletOutputStream out = response.getOutputStream(); 067 feedOutput.output(wireFeed, new OutputStreamWriter(out, wireFeed.getEncoding())); 068 out.flush(); 069 } 070 071 /** 072 * Create a new feed to hold the entries. 073 * @return the newly created Feed instance 074 */ 075 protected abstract T newFeed(); 076 077 /** 078 * Populate the feed metadata (title, link, description, etc.). 079 * <p>Default is an empty implementation. Subclasses can override this method 080 * to add meta fields such as title, link description, etc. 081 * @param model the model, in case meta information must be populated from it 082 * @param feed the feed being populated 083 * @param request in case we need locale etc. Shouldn't look at attributes. 084 */ 085 protected void buildFeedMetadata(Map<String, Object> model, T feed, HttpServletRequest request) { 086 } 087 088 /** 089 * Subclasses must implement this method to build feed entries, given the model. 090 * <p>Note that the passed-in HTTP response is just supposed to be used for 091 * setting cookies or other HTTP headers. The built feed itself will automatically 092 * get written to the response after this method returns. 093 * @param model the model Map 094 * @param feed the feed to add entries to 095 * @param request in case we need locale etc. Shouldn't look at attributes. 096 * @param response in case we need to set cookies. Shouldn't write to it. 097 * @throws Exception any exception that occurred during building 098 */ 099 protected abstract void buildFeedEntries(Map<String, Object> model, T feed, 100 HttpServletRequest request, HttpServletResponse response) throws Exception; 101 102}