AbstractCacheableController


1   /* ***** BEGIN LICENSE BLOCK *****
2    * Version: MPL 1.1
3    * The contents of this file are subject to the Mozilla Public License Version
4    * 1.1 (the "License"); you may not use this file except in compliance with
5    * the License. You may obtain a copy of the License at
6    * http://www.mozilla.org/MPL/
7    * 
8    * Software distributed under the License is distributed on an "AS IS" basis,
9    * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
10   * for the specific language governing rights and limitations under the
11   * License.
12   * 
13   * The Original Code is Riot.
14   * 
15   * The Initial Developer of the Original Code is
16   * Neteye GmbH.
17   * Portions created by the Initial Developer are Copyright (C) 2006
18   * the Initial Developer. All Rights Reserved.
19   * 
20   * Contributor(s):
21   *   Felix Gnass [fgnass at neteye dot de]
22   * 
23   * ***** END LICENSE BLOCK ***** */
24  package org.riotfamily.cachius.spring;
25  
26  import javax.servlet.http.HttpServletRequest  ;
27  
28  import org.riotfamily.common.web.util.ServletUtils;
29  import org.springframework.beans.factory.BeanNameAware;
30  
31  
32  /**
33   * Abstract base class for cacheable controllers.
34   * 
35   * @author Felix Gnass
36   */
37  public abstract class AbstractCacheableController 
38          implements CacheableController, BeanNameAware {
39  
40      private String   beanName;
41      
42      public final void setBeanName(String   beanName) {
43          this.beanName = beanName;
44      }
45          
46      protected String   getBeanName() {
47          return beanName;
48      }
49      
50      /**
51       * Returns the cache-key for the request unless 
52       * {@link #bypassCache(HttpServletRequest)} returns <code>true</code>.
53       * The method creates a StringBuffer and appends the controller's beanName.
54       * The buffer is passed to {@link #appendCacheKey(StringBuffer, HttpServletRequest)}
55       * allowing subclasses to add further values to the key.
56       */
57      public final String   getCacheKey(HttpServletRequest   request) {
58          if (bypassCache(request)) {
59              return null;
60          }
61          StringBuffer   key = new StringBuffer  ();
62          key.append(beanName).append(':');
63          appendCacheKey(key, request);
64          return key.toString();
65      }
66              
67      /**
68       * Returns whether the cache should be bypassed. The default implementation 
69       * always returns <code>false</code>. 
70       */
71      protected boolean bypassCache(HttpServletRequest   request) {
72          return false;
73      }
74  
75      /**
76       * Subclasses may overwrite this method to append values to the cache-key.
77       * The default implementation appends the {@link 
78       * ServletUtils#getOriginatingRequestUri(HttpServletRequest) originating
79       * requestURI}.
80       */
81      protected void appendCacheKey(StringBuffer   key, HttpServletRequest   request) {
82          key.append(ServletUtils.getOriginatingRequestUri(request));
83      }
84  
85      /**
86       * The default implementation returns <code>0</code> so that 
87       * {@link #getLastModified(HttpServletRequest)} is invoked every time the
88       * controller is requested.
89       */
90      public long getTimeToLive() {
91          return 0;
92      }
93      
94      /**
95       * The default implementation returns 
96       * <code>System.currentTimeMillis()</code> so that the item is 
97       * refreshed as soon as it expires. Subclasses should override this
98       * method to return something reasonable.
99       */
100     public long getLastModified(HttpServletRequest   request) {
101         return System.currentTimeMillis();
102     }
103     
104 }
105
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