BlogBrowserServlet


1   /*
2    * Copyright (c) 2003 - 2007 OpenSubsystems s.r.o. Slovak Republic. All rights reserved.
3    * 
4    * Project: OpenChronicle
5    * 
6    * $Id: BlogBrowserServlet.java,v 1.6 2007/02/20 02:01:38 bastafidli Exp $
7    * 
8    * This program is free software; you can redistribute it and/or modify
9    * it under the terms of the GNU General Public License as published by
10   * the Free Software Foundation; version 2 of the License. 
11   * 
12   * This program is distributed in the hope that it will be useful,
13   * but WITHOUT ANY WARRANTY; without even the implied warranty of
14   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15   * GNU General Public License for more details.
16   * 
17   * You should have received a copy of the GNU General Public License
18   * along with this program; if not, write to the Free Software
19   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA 
20   */
21  
22  package org.opensubsystems.blog.www;
23  
24  import java.io.IOException  ;
25  import java.util.List  ;
26  import java.util.logging.Level  ;
27  import java.util.logging.Logger  ;
28  
29  import javax.servlet.ServletConfig  ;
30  import javax.servlet.ServletException  ;
31  import javax.servlet.http.HttpServletRequest  ;
32  import javax.servlet.http.HttpServletResponse  ;
33  
34  import org.opensubsystems.blog.logic.BlogController;
35  import org.opensubsystems.core.error.OSSException;
36  import org.opensubsystems.core.logic.ControllerManager;
37  import org.opensubsystems.core.util.Log;
38  import org.opensubsystems.core.www.WebUIServlet;
39  import org.opensubsystems.core.www.WebUtils;
40  
41  /**
42   * Servlet responsible for browsing blogs and their entries as if they were 
43   * displayed using a static website consisting of pages with .html extension.
44   * his servlet contains read-only functionality so it can be safely used, when 
45   * user shouldn't be allowed to modify the data.
46   *
47   * @version $Id: BlogBrowserServlet.java,v 1.6 2007/02/20 02:01:38 bastafidli Exp $
48   * @author Miro Halas
49   * @code.reviewer Miro Halas
50   * @code.reviewed Initial revision
51   */
52  public class BlogBrowserServlet extends WebUIServlet
53  {
54     // Configuration settings ///////////////////////////////////////////////////
55     
56     /** 
57      * Name of the property for page which is the main entry point to the blog 
58      * functionality.
59      */   
60     public static final String   BLOGBROWSER_BLOG_INDEX_PAGE = "blogbrowser.blog.index.page";
61  
62     /** 
63      * Name of the property for page to view single blog.
64      */   
65     public static final String   BLOGBROWSER_BLOG_VIEWER_PAGE = "blogbrowser.blog.viewer.page";
66  
67     /** 
68      * Name of the property for page to view single blog entry.
69      */   
70     public static final String   BLOGBROWSER_BLOGENTRY_VIEWER_PAGE 
71                                   = "blogbrowser.entry.viewer.page";
72  
73     // Constants ////////////////////////////////////////////////////////////////
74  
75     /**
76      * Constant for number of forms recognized by this servlet
77      */
78     public static final int FORM_COUNT_BLOGBROWSER = FORM_COUNT_WEBUI;
79  
80     // Cached values ////////////////////////////////////////////////////////////
81  
82     /**
83      * Logger for this class
84      */
85     private static Logger   s_logger = Log.getInstance(BlogBrowserServlet.class);
86  
87     // Attributes ///////////////////////////////////////////////////////////////
88  
89     /**
90      * Generated serial version id for this class.
91      */
92     private static final long serialVersionUID = 3131866602964809055L;
93  
94     // Public methods ///////////////////////////////////////////////////////////
95  
96     /**
97      * {@inheritDoc}
98      */
99     public void init(
100       ServletConfig   scConfig
101    ) throws ServletException  
102    {
103       super.init(scConfig);
104 
105       // Load UI pages for this blog
106       // The main entry point to the blog functionality
107       cacheUIPath(scConfig, BLOGBROWSER_BLOG_INDEX_PAGE, 
108                   "Path to main index page is not set in property " 
109                   + BLOGBROWSER_BLOG_INDEX_PAGE);
110       
111       // Page to view single blog
112       cacheUIPath(scConfig, BLOGBROWSER_BLOG_VIEWER_PAGE, 
113                   "Path to blog viewer page is not set in property " 
114                   + BLOGBROWSER_BLOG_INDEX_PAGE);
115 
116       // Page to view single blog entry
117       cacheUIPath(scConfig, BLOGBROWSER_BLOGENTRY_VIEWER_PAGE, 
118                   "Path to  entry viewer page is not set in property " 
119                   + BLOGBROWSER_BLOGENTRY_VIEWER_PAGE);
120    }
121 
122    /**
123     * {@inheritDoc}
124     */
125    protected void doGet(
126       HttpServletRequest    hsrqRequest,
127       HttpServletResponse   hsrpResponse
128    ) throws ServletException  , 
129             IOException  
130    {
131       if (WebUtils.isIndexPage(hsrqRequest))
132       {
133          if (WebUtils.isMainIndexPage(hsrqRequest))
134          {
135             // Create page displaying all existing blogs
136             createMainIndexPage(hsrqRequest, hsrpResponse);
137          }
138          else
139          {
140             // Create page displaying one blog
141             createIndexPage(hsrqRequest, hsrpResponse);
142          }
143       }
144       else
145       {
146          if (WebUtils.isStaticWebPage(hsrqRequest))
147          {
148             // Create page displaying one entry of a blogs
149             createBlogEntryPage(hsrqRequest, hsrpResponse);
150          }
151          else
152          {
153             hsrpResponse.sendError(HttpServletResponse.SC_NOT_FOUND);
154          }
155       }
156    }
157 
158    /**
159     * {@inheritDoc}
160     */
161    public String   getServletInfo(
162    )
163    {
164       return this.getClass().getName();
165    }
166    
167    // Helper methods ///////////////////////////////////////////////////////////
168 
169    /**
170     * Create main index page of all blogs. 
171     *
172     * @param  hsrqRequest  - the servlet request
173     * @param  hsrpResponse - the servlet response
174     * @throws ServletException - an error while serving request
175     * @throws IOException - an error while writing response
176     */
177    protected void createMainIndexPage(
178       HttpServletRequest    hsrqRequest,
179       HttpServletResponse   hsrpResponse
180    ) throws IOException  ,
181             ServletException  
182    {
183       s_logger.entering(this.getClass().getName(), "createMainIndexPage");
184 
185       try
186       {
187          List   lstBlogs;
188 
189          lstBlogs = getController().getAll();
190          if (lstBlogs != null)
191          {
192             hsrqRequest.setAttribute("blogs", lstBlogs);
193          }
194          hsrqRequest.setAttribute("blognavigator", getNavigator(hsrqRequest));
195          displayUI(BLOGBROWSER_BLOG_INDEX_PAGE, hsrqRequest, hsrpResponse);
196       }
197       catch (Exception   eExc)
198       {
199          s_logger.log(Level.WARNING, 
200                       "An error has occured while retrieving list of blogs.", 
201                       eExc);
202          messageBoxPage(hsrqRequest, hsrpResponse, "Error", eExc.getMessage(),
203                         getNavigator(hsrqRequest).getRootURL(),
204                         eExc.getCause());
205       }
206       finally
207       {
208          s_logger.exiting(this.getClass().getName(), "createMainIndexPage");
209       }
210    }
211 
212    /**
213     * Create index page of all entries in the blog.
214     *
215     * @param  hsrqRequest  - the servlet request
216     * @param  hsrpResponse - the servlet response
217     * @throws ServletException - an error while serving request
218     * @throws IOException - an error while writing response
219     */
220    protected void createIndexPage(
221       HttpServletRequest    hsrqRequest,
222       HttpServletResponse   hsrpResponse
223    ) throws IOException  ,
224             ServletException  
225    {
226       s_logger.entering(this.getClass().getName(), "createIndexPage");
227 
228       try
229       {
230          Object     objBlogIdentification;
231          Object  [] arObjects;
232          BlogNavigator navigator;
233 
234          navigator = getNavigator(hsrqRequest);
235          objBlogIdentification = navigator.getBlogIdentification(hsrqRequest);
236          arObjects = getController().getWithEntries((String  )objBlogIdentification);
237                   
238          if ((arObjects != null) && (arObjects[0] != null)) 
239          {
240             hsrqRequest.setAttribute("blog", arObjects[0]);
241             // It is ok to do not have any entries
242             if (arObjects[1] != null)
243             {
244                hsrqRequest.setAttribute("blogentries", arObjects[1]);
245             }
246             hsrqRequest.setAttribute("blognavigator", navigator);
247             displayUI(BLOGBROWSER_BLOG_VIEWER_PAGE, hsrqRequest, hsrpResponse);
248          }
249          else
250          {
251             // We have found either the blog or the entry so tell the user
252             // about it 
253             hsrpResponse.sendError(HttpServletResponse.SC_NOT_FOUND);
254          }
255       }
256       catch (Exception   eExc)
257       {
258          s_logger.log(Level.WARNING, "An error has occured while retrieving blog.", 
259                       eExc);
260          messageBoxPage(hsrqRequest, hsrpResponse, "Error", eExc.getMessage(),
261                         getNavigator(hsrqRequest).getRootURL(),
262                         eExc.getCause());
263       }
264       finally
265       {
266          s_logger.exiting(this.getClass().getName(), "createIndexPage");
267       }
268    }
269 
270    /**
271     * Create blog page for the path requested by user
272     *
273     * @param  hsrqRequest  - the servlet request
274     * @param  hsrpResponse - the servlet response
275     * @throws ServletException - an error while serving request
276     * @throws IOException - an error while writing response
277     */
278    protected void createBlogEntryPage(
279       HttpServletRequest    hsrqRequest,
280       HttpServletResponse   hsrpResponse
281    ) throws IOException  ,
282             ServletException  
283    {
284       s_logger.entering(this.getClass().getName(), "createBlogEntryPage");
285 
286       try
287       {
288          BlogEntryIdentification entryIdentification;
289          Object  []                arObjects = null;
290          BlogNavigator           navigator;
291          
292          navigator = getNavigator(hsrqRequest);
293          entryIdentification = navigator.getBlogEntryIdentification(hsrqRequest);
294          if (entryIdentification != null)
295          {                                                            
296             arObjects = getController().getWithEntry(
297                            (String  )entryIdentification.getBlogIdentification(),
298                            entryIdentification.getBlogEntryIdentification());
299          }
300          
301          if ((arObjects != null) && (arObjects[0] != null) 
302             && (arObjects[1] != null)) 
303          {
304             hsrqRequest.setAttribute("blog", arObjects[0]);
305             hsrqRequest.setAttribute("blogentry", arObjects[1]);
306             hsrqRequest.setAttribute("blognavigator", navigator);
307             displayUI(BLOGBROWSER_BLOGENTRY_VIEWER_PAGE, hsrqRequest, hsrpResponse);
308          }
309          else
310          {
311             // We have not found either the blog or the entry so tell the user
312             // about it 
313             hsrpResponse.sendError(HttpServletResponse.SC_NOT_FOUND);
314          }
315       }
316       catch (Exception   eExc)
317       {
318          s_logger.log(Level.WARNING, 
319                       "An error has occured while retrieving blog entry.", 
320                       eExc);
321          messageBoxPage(hsrqRequest, hsrpResponse, "Error", eExc.getMessage(),
322                         getNavigator(hsrqRequest).getRootURL(), eExc.getCause());
323       }
324       finally
325       {
326          s_logger.exiting(this.getClass().getName(), "createBlogEntryPage");
327       }
328    }
329 
330    // Helper methods ///////////////////////////////////////////////////////////
331    
332    /**
333     * Get instance of navigator object suitable for processing current request.
334     *
335     * @param hsrqRequest - current request
336     * @return BlogNavigator - navigator for current request
337     */
338    protected BlogNavigator getNavigator(
339       HttpServletRequest   hsrqRequest
340    )
341    {
342       return new BlogNavigator(hsrqRequest);
343    }
344 
345    /**
346     * Get controller to invoke business logic.
347     * 
348     * @return BlogController
349     * @throws OSSException - an error has occured
350     */
351    protected BlogController getController(
352    ) throws OSSException
353    {
354       BlogController controller;
355       
356       controller = (BlogController)ControllerManager.getInstance(
357                                                         BlogController.class);
358       
359       return controller;
360    }
361 }
362
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