CachingInterceptor xref

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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    * 
9    *      http://www.apache.org/licenses/LICENSE-2.0
10   * 
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  package org.apache.jetspeed.components.interceptors;
18  
19  import org.aopalliance.intercept.MethodInvocation;
20  import org.apache.jetspeed.cache.general.GeneralCache;
21  
22  /***
23   * <p>
24   * CacheInterceptor
25   * </p>
26   * <p>
27   *  AoP Interceptor that can be used for generalized caching.  The only requirement is
28   *  that intercepted methods must receive at least one (1) arguments.
29   *  <br /> <br />  
30   *  CacheInterceptor ALWAYS use the first argument in the method to build the unique cache key. 
31   * </p>
32   * 
33   * @author <a href="mailto:weaver@apache.org">Scott T. Weaver </a>
34   * @version $Id: CachingInterceptor.java 516448 2007-03-09 16:25:47Z ate $
35   *  
36   */
37  public class CachingInterceptor extends AbstractCacheInterceptor
38  {
39  
40     
41      
42      /***
43       * @param cache
44       */
45      public CachingInterceptor( GeneralCache cache )
46      {
47          super(cache);
48      }
49  
50      /***
51       * <p>
52       * doCacheOperation
53       * </p>
54       *
55       * @param mi
56       * @param uniqueKey
57       * @return
58       * @throws Throwable
59       */
60      protected Object doCacheOperation( MethodInvocation mi, String uniqueKey ) throws Throwable
61      {
62          if(cache.contains(uniqueKey))
63          {
64              return cache.get(uniqueKey);
65          }
66          else
67          {
68              Object value = mi.proceed();
69              if(value != null)
70              {
71                  cache.put(uniqueKey, value);
72              }
73              
74              return value;
75          }
76      }
77  }