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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one
3    * or more contributor license agreements.  See the NOTICE file
4    * distributed with this work for additional information
5    * regarding copyright ownership.  The ASF licenses this file
6    * to you under the Apache License, Version 2.0 (the
7    * "License"); you may not use this file except in compliance
8    * with the License.  You may obtain a copy of the License at
9    *
10   *   http://www.apache.org/licenses/LICENSE-2.0
11   *
12   * Unless required by applicable law or agreed to in writing,
13   * software distributed under the License is distributed on an
14   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15   * KIND, either express or implied.  See the License for the
16   * specific language governing permissions and limitations
17   * under the License.
18   */
19  
20  package org.apache.myfaces.orchestra.conversation.spring;
21  
22  import org.aopalliance.intercept.MethodInterceptor;
23  import org.aopalliance.intercept.MethodInvocation;
24  import org.apache.myfaces.orchestra.conversation.Conversation;
25  
26  /**
27   * Maintain the appropriate persistence state for the current call-stack.
28   * <p>
29   * This class is a MethodInterceptor (an AOP Advice) which should be configured to intercept
30   * calls to all conversation-scoped beans. It ensures that the appropriate PersistenceContext
31   * object for this conversation is placed into the default location, by invoking the
32   * <i>bind</i> method on the persistence context object. Typically the bind method stores
33   * the persistence context into a thread-local variable, but that is implementation-specific.
34   * <p>
35   * When Spring code retrieves the persistence context in order to inject it into a bean,
36   * it then finds the correct context for the conversation that is associated with the
37   * nearest conversation-scoped bean in the callstack.    
38   * <p>
39   * If no PersistenceContext yet exists for the conversation associated with the bean
40   * that is being invoked then one is created using {@link PersistenceContextFactory}.
41   * <p>
42   * A reference to the {@link PersistenceContext} is put into the conversation attribute
43   * map wrapped in an {@link PersistenceContextCloser} so that when the conversation
44   * ends a callback occurs on it which closes the underlying object.
45   */
46  public class PersistenceContextConversationInterceptor implements MethodInterceptor
47  {
48      private final static String PERSISTENCE_CONTEXT_CONV_ATTRIBUTE =
49          PersistenceContextConversationInterceptor.class.getName() + ".PERSISTENCE_CONTEXT";
50      public final static String REQUEST_ATTRIBUTE =
51          PersistenceContextConversationInterceptor.class.getName() + ".USED_PERSISTENCE_CONTEXTS";
52  
53      private PersistenceContextFactory persistenceContextFactory;
54  
55      public PersistenceContextConversationInterceptor()
56      {
57      }
58  
59      public void setPersistenceContextFactory(PersistenceContextFactory persistenceContextFactory)
60      {
61          this.persistenceContextFactory = persistenceContextFactory;
62      }
63  
64      public Object invoke(MethodInvocation methodInvocation) throws Throwable
65      {
66          PersistenceContext persistenceContext = null;
67  
68          Conversation conversation = Conversation.getCurrentInstance();
69          if (conversation != null)
70          {
71              PersistenceContextCloser persistenceContextCloser = (PersistenceContextCloser)
72                  conversation.getAttribute(PERSISTENCE_CONTEXT_CONV_ATTRIBUTE);
73              if (persistenceContextCloser != null)
74              {
75                  persistenceContext = persistenceContextCloser.getPersistenceContext();
76              }
77  
78              if (persistenceContext == null)
79              {
80                  persistenceContext = persistenceContextFactory.create();
81  
82                  conversation.setAttribute(
83                      PERSISTENCE_CONTEXT_CONV_ATTRIBUTE,
84                      new PersistenceContextCloser(persistenceContext));
85              }
86          }
87  
88          if (persistenceContext != null)
89          {
90              // registerPersistenceContextUsage(persistenceContext);
91  
92              persistenceContext.bind();
93          }
94  
95          try
96          {
97              return methodInvocation.proceed();
98          }
99          finally
100         {
101             if (persistenceContext != null)
102             {
103                 persistenceContext.unbind();
104             }
105         }
106     }
107 
108     /*
109     protected void registerPersistenceContextUsage(PersistenceContext persistenceContext)
110     {
111         FrameworkAdapterInterface fai = FrameworkAdapter.getInstance();
112         Set persistencesContexts = (Set) fai.getRequestAttribute(REQUEST_ATTRIBUTE);
113         if (persistencesContexts == null)
114         {
115             persistencesContexts = new HashSet();
116             fai.setRequestAttribute(REQUEST_ATTRIBUTE, persistencesContexts);
117         }
118         if (!persistencesContexts.contains(persistenceContext))
119         {
120             persistencesContexts.add(persistenceContext);
121         }
122     }
123 
124     public static void cleanupPersistence()
125     {
126         FrameworkAdapterInterface fai = FrameworkAdapter.getInstance();
127         Set persistencesContexts = (Set) fai.getRequestAttribute(REQUEST_ATTRIBUTE);
128         if (persistencesContexts == null)
129         {
130             return;
131         }
132 
133         Iterator iterPersistencesContexts = persistencesContexts.iterator();
134         while (iterPersistencesContexts.hasNext())
135         {
136             PersistenceContext persistenceContext = (PersistenceContext) iterPersistencesContexts.next();
137             persistenceContext.unbind();
138         }
139     }
140     */
141 }