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Java > Open Source Codes > org > snipsnap > interceptor > custom > MissingInterceptor


1 /*
2  * This file is part of "SnipSnap Wiki/Weblog".
3  *
4  * Copyright (c) 2002 Stephan J. Schmidt, Matthias L. Jugel
5  * All Rights Reserved.
6  *
7  * Please visit http://snipsnap.org/ for updates and contact.
8  *
9  * --LICENSE NOTICE--
10  * This program is free software; you can redistribute it and/or
11  * modify it under the terms of the GNU General Public License
12  * as published by the Free Software Foundation; either version 2
13  * of the License, or (at your option) any later version.
14  *
15  * This program is distributed in the hope that it will be useful,
16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18  * GNU General Public License for more details.
19  *
20  * You should have received a copy of the GNU General Public License
21  * along with this program; if not, write to the Free Software
22  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
23  * --LICENSE NOTICE--
24  */
25
26 package org.snipsnap.interceptor.custom;
27
28 import org.snipsnap.interceptor.InterceptorSupport;
29 import org.snipsnap.interceptor.Invocation;
30
31 import java.util.HashSet JavaDoc;
32 import java.util.Set JavaDoc;
33
34 /**
35  * Interceptor for caching SnipSpace misses. SnipSnap
36  * often calls exists() to detect if a snip exists.
37  * This operation can be costly so we keep the results
38  * to exists() cached.
39  *
40  * @author Stephan J. Schmidt
41  * @version $Id: MissingInterceptor.java 876 2003-05-30 12:46:32Z stephan $
42  */
43 public class MissingInterceptor extends InterceptorSupport {
44   // @TODO we use map instead of set to increment the
45 // missing counter each time a snip could not be found
46 private Set JavaDoc missing;
47
48   public MissingInterceptor() {
49     super();
50     missing = new HashSet JavaDoc();
51   }
52
53   public Set JavaDoc getMissing() {
54     return missing;
55   }
56
57   public Object JavaDoc invoke(Invocation invocation) throws Throwable JavaDoc {
58     String JavaDoc method = invocation.getMethod().getName();
59
60     // exists(): return cache if possible
61 if ("exists".equals(method)) {
62       String JavaDoc name = ((String JavaDoc) invocation.getArgs()[0]).toUpperCase();
63       if (missing.contains(name)) {
64         return Boolean.FALSE;
65       }
66       Object JavaDoc result = invocation.next();
67       if (Boolean.FALSE.equals(result)) {
68         missing.add(name);
69       }
70       return result;
71       // create() remove from missing list
72 } else if ("create".equals(method)) {
73       String JavaDoc name = ((String JavaDoc) invocation.getArgs()[0]).toUpperCase();
74       if (missing.contains(name.toUpperCase())) {
75         missing.remove(name);
76       }
77     }
78     Object JavaDoc result = invocation.next();
79     return result;
80   }
81 }
82
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