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Java > Open Source Codes > org > apache > roller > ui > rendering > servlets > FeedServlet


1 /*
2  * Licensed to the Apache Software Foundation (ASF) under one or more
3  * contributor license agreements. The ASF licenses this file to You
4  * under the Apache License, Version 2.0 (the "License"); you may not
5  * use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  * http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License. For additional information regarding
15  * copyright in this work, please see the NOTICE file in the top level
16  * directory of this distribution.
17  */
18
19 package org.apache.roller.ui.rendering.servlets;
20
21 import java.io.IOException JavaDoc;
22 import java.util.HashMap JavaDoc;
23 import java.util.Map JavaDoc;
24 import javax.servlet.ServletConfig JavaDoc;
25 import javax.servlet.ServletException JavaDoc;
26 import javax.servlet.http.HttpServlet JavaDoc;
27 import javax.servlet.http.HttpServletRequest JavaDoc;
28 import javax.servlet.http.HttpServletResponse JavaDoc;
29 import org.apache.commons.logging.Log;
30 import org.apache.commons.logging.LogFactory;
31 import org.apache.roller.RollerException;
32 import org.apache.roller.config.RollerConfig;
33 import org.apache.roller.config.RollerRuntimeConfig;
34 import org.apache.roller.pojos.StaticTemplate;
35 import org.apache.roller.pojos.Template;
36 import org.apache.roller.pojos.WebsiteData;
37 import org.apache.roller.ui.rendering.util.WeblogFeedRequest;
38 import org.apache.roller.util.cache.CachedContent;
39 import org.apache.roller.ui.rendering.Renderer;
40 import org.apache.roller.ui.rendering.RendererManager;
41 import org.apache.roller.ui.rendering.model.ModelLoader;
42 import org.apache.roller.ui.rendering.util.SiteWideCache;
43 import org.apache.roller.ui.rendering.util.WeblogFeedCache;
44 import org.apache.roller.ui.rendering.util.ModDateHeaderUtil;
45
46
47 /**
48  * Responsible for rendering weblog feeds.
49  *
50  * @web.servlet name="FeedServlet" load-on-startup="5"
51  * @web.servlet-mapping url-pattern="/roller-ui/rendering/feed/*"
52  */
53 public class FeedServlet extends HttpServlet JavaDoc {
54
55     private static Log log = LogFactory.getLog(FeedServlet.class);
56
57     private WeblogFeedCache weblogFeedCache = null;
58     private SiteWideCache siteWideCache = null;
59
60
61     /**
62      * Init method for this servlet
63      */
64     public void init(ServletConfig JavaDoc servletConfig) throws ServletException JavaDoc {
65
66         super.init(servletConfig);
67
68         log.info("Initializing FeedServlet");
69
70         // get a reference to the weblog feed cache
71 this.weblogFeedCache = WeblogFeedCache.getInstance();
72
73         // get a reference to the site wide cache
74 this.siteWideCache = SiteWideCache.getInstance();
75     }
76
77
78     /**
79      * Handle GET requests for weblog feeds.
80      */
81     public void doGet(HttpServletRequest JavaDoc request, HttpServletResponse JavaDoc response)
82             throws ServletException JavaDoc, IOException JavaDoc {
83
84         log.debug("Entering");
85
86         WebsiteData weblog = null;
87         boolean isSiteWide = false;
88
89         WeblogFeedRequest feedRequest = null;
90         try {
91             // parse the incoming request and extract the relevant data
92 feedRequest = new WeblogFeedRequest(request);
93
94             weblog = feedRequest.getWeblog();
95             if(weblog == null) {
96                 throw new RollerException("unable to lookup weblog: "+
97                         feedRequest.getWeblogHandle());
98             }
99
100             // is this the site-wide weblog?
101 isSiteWide = RollerRuntimeConfig.isSiteWideWeblog(feedRequest.getWeblogHandle());
102
103         } catch(Exception JavaDoc e) {
104             // invalid feed request format or weblog doesn't exist
105 log.debug("error creating weblog feed request", e);
106             response.sendError(HttpServletResponse.SC_NOT_FOUND);
107             return;
108         }
109
110
111         // determine the lastModified date for this content
112 long lastModified = System.currentTimeMillis();
113         if(isSiteWide) {
114             lastModified = siteWideCache.getLastModified().getTime();
115         } else if (weblog.getLastModified() != null) {
116             lastModified = weblog.getLastModified().getTime();
117         }
118
119         // Respond with 304 Not Modified if it is not modified.
120 if (ModDateHeaderUtil.respondIfNotModified(request,response,lastModified)) {
121             return;
122         }
123
124         // set last-modified date
125 ModDateHeaderUtil.setLastModifiedHeader(response, lastModified);
126
127         // set content type
128 String JavaDoc accepts = request.getHeader("Accept");
129         String JavaDoc userAgent = request.getHeader("User-Agent");
130         if (RollerRuntimeConfig.getBooleanProperty("site.newsfeeds.styledFeeds") &&
131             accepts != null && accepts.indexOf("*/*") != -1 &&
132             userAgent != null && userAgent.startsWith("Mozilla")) {
133             // client is a browser and feed style is enabled so we want
134 // browsers to load the page rather than popping up the download
135 // dialog, so we provide a content-type that browsers will display
136 response.setContentType("text/xml");
137         } else if("rss".equals(feedRequest.getFormat())) {
138             response.setContentType("application/rss+xml; charset=utf-8");
139         } else if("atom".equals(feedRequest.getFormat())) {
140             response.setContentType("application/atom+xml; charset=utf-8");
141         }
142
143         // generate cache key
144 String JavaDoc cacheKey = null;
145         if(isSiteWide) {
146             cacheKey = siteWideCache.generateKey(feedRequest);
147         } else {
148             cacheKey = weblogFeedCache.generateKey(feedRequest);
149         }
150
151         // cached content checking
152 CachedContent cachedContent = null;
153         if(isSiteWide) {
154             cachedContent = (CachedContent) siteWideCache.get(cacheKey);
155         } else {
156             cachedContent = (CachedContent) weblogFeedCache.get(cacheKey, lastModified);
157         }
158
159         if(cachedContent != null) {
160             log.debug("HIT "+cacheKey);
161
162             response.setContentLength(cachedContent.getContent().length);
163             response.getOutputStream().write(cachedContent.getContent());
164             return;
165
166         } else {
167             log.debug("MISS "+cacheKey);
168         }
169
170
171         // looks like we need to render content
172 HashMap JavaDoc model = new HashMap JavaDoc();
173         String JavaDoc pageId = null;
174         try {
175             // determine what template to render with
176 if (RollerRuntimeConfig.isSiteWideWeblog(weblog.getHandle())) {
177                 pageId = "templates/feeds/site-"+feedRequest.getType()+"-"+feedRequest.getFormat()+".vm";
178             } else {
179                 pageId = "templates/feeds/weblog-"+feedRequest.getType()+"-"+feedRequest.getFormat()+".vm";
180             }
181
182             // populate the rendering model
183 Map JavaDoc initData = new HashMap JavaDoc();
184             initData.put("request", request);
185             initData.put("weblogRequest", feedRequest);
186
187             // Load models for feeds
188 String JavaDoc feedModels = RollerConfig.getProperty("rendering.feedModels");
189             ModelLoader.loadModels(feedModels, model, initData, true);
190
191             // Load special models for site-wide blog
192
193             if(RollerRuntimeConfig.isSiteWideWeblog(weblog.getHandle())) {
194                 String JavaDoc siteModels = RollerConfig.getProperty("rendering.siteModels");
195                 ModelLoader.loadModels(siteModels, model, initData, true);
196             }
197
198             // TODO: re-enable custom models once feeds are customizable
199 // Load weblog custom models
200 //ModelLoader.loadCustomModels(weblog, model, initData);
201
202         } catch (RollerException ex) {
203             log.error("ERROR loading model for page", ex);
204
205             if(!response.isCommitted()) response.reset();
206             response.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
207             return;
208         }
209
210
211         // lookup Renderer we are going to use
212 Renderer renderer = null;
213         try {
214             log.debug("Looking up renderer");
215             Template template = new StaticTemplate(pageId, null, "velocity");
216             renderer = RendererManager.getRenderer(template);
217         } catch(Exception JavaDoc e) {
218             // nobody wants to render my content :(
219
220             // TODO: this log message has been disabled because it fills up
221 // the logs with useless errors due to the fact that the way these
222 // template ids are formed comes directly from the request and it
223 // often gets bunk data causing invalid template ids.
224 // at some point we should have better validation on the input so
225 // that we can quickly dispatch invalid feed requests and only
226 // get this far if we expect the template to be found
227 //log.error("Couldn't find renderer for page "+pageId, e);
228
229             if(!response.isCommitted()) response.reset();
230             response.sendError(HttpServletResponse.SC_NOT_FOUND);
231             return;
232         }
233
234         // render content. use default size of about 24K for a standard page
235 CachedContent rendererOutput = new CachedContent(24567);
236         try {
237             log.debug("Doing rendering");
238             renderer.render(model, rendererOutput.getCachedWriter());
239
240             // flush rendered output and close
241 rendererOutput.flush();
242             rendererOutput.close();
243         } catch(Exception JavaDoc e) {
244             // bummer, error during rendering
245 log.error("Error during rendering for page "+pageId, e);
246
247             if(!response.isCommitted()) response.reset();
248             response.sendError(HttpServletResponse.SC_NOT_FOUND);
249             return;
250         }
251
252
253         // post rendering process
254
255         // flush rendered content to response
256 log.debug("Flushing response output");
257         response.setContentLength(rendererOutput.getContent().length);
258         response.getOutputStream().write(rendererOutput.getContent());
259
260         // cache rendered content. only cache if user is not logged in?
261 log.debug("PUT "+cacheKey);
262         if(isSiteWide) {
263             siteWideCache.put(cacheKey, rendererOutput);
264         } else {
265             weblogFeedCache.put(cacheKey, rendererOutput);
266         }
267
268         log.debug("Exiting");
269     }
270
271 }
272
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