DListEntry


1   package org.apache.ojb.odmg.collections;
2   
3   /* Copyright 2003-2005 The Apache Software Foundation
4    *
5    * Licensed under the Apache License, Version 2.0 (the "License");
6    * you may not use this file except in compliance with the License.
7    * 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  
18  import java.io.Serializable  ;
19  
20  import org.apache.commons.lang.builder.ToStringBuilder;
21  import org.apache.ojb.broker.Identity;
22  import org.apache.ojb.broker.OJBRuntimeException;
23  import org.apache.ojb.broker.PBKey;
24  import org.apache.ojb.broker.PersistenceBroker;
25  import org.apache.ojb.broker.PersistenceBrokerAware;
26  import org.apache.ojb.broker.PersistenceBrokerException;
27  import org.apache.ojb.broker.util.logging.Logger;
28  import org.apache.ojb.broker.util.logging.LoggerFactory;
29  import org.apache.ojb.odmg.PBCapsule;
30  import org.apache.ojb.odmg.RuntimeObject;
31  import org.apache.ojb.odmg.TransactionImpl;
32  import org.apache.ojb.odmg.TxManagerFactory;
33  import org.odmg.Transaction;
34  
35  /**
36   * Encapsulates an DList entry object.
37   *
38   * @version $Id: DListEntry.java,v 1.25.2.4 2005/12/21 22:29:50 tomdz Exp $
39   */
40  public class DListEntry implements Serializable  , PersistenceBrokerAware
41  {
42      private static final long serialVersionUID = 5251476492626009907L;
43      /*
44       * declare transient, because ManageableCollection entries need to be {@link java.io.Serializable}.
45       */
46      private transient Logger log;
47      protected transient Object   realSubject;
48      protected PBKey pbKey;
49  
50      protected Integer   id;
51      protected Integer   dlistId;
52      protected Identity oid;
53      protected int position;
54  
55      /**
56       * Used to instantiate persistent DLists from DB by the kernel
57       * FOR INTERNAL USE ONLY
58       */
59      public DListEntry()
60      {
61          /*
62          arminw:
63          When PB kernel fill DList with DListEntry, the DListEntry needs to know the current
64          used PBKey, because we need to lookup the real objects when user iterates the list,
65          thus we need the associated PBKey to find right PB/DB connection.
66          TODO: Find a better solution
67          */
68  //        if(getTransaction() == null)
69  //        {
70  //            throw new TransactionNotInProgressException("Materialization of DCollection instances must be done with a tx");
71  //        }
72          getPBKey();
73      }
74  
75      /**
76       * Standard way to instantiate new entries
77       */
78      public DListEntry(DListImpl theDList, Object   theObject)
79      {
80          this.dlistId = theDList.getId();
81          this.position = theDList.size();
82          this.realSubject = theObject;
83          this.pbKey = getPBKey();
84      }
85  
86      protected Logger getLog()
87      {
88          if(log == null)
89          {
90              log = LoggerFactory.getLogger(DListEntry.class);
91          }
92          return log;
93      }
94  
95      protected TransactionImpl getTransaction()
96      {
97          return TxManagerFactory.instance().getTransaction();
98      }
99  
100     public PBKey getPBKey()
101     {
102         if(pbKey == null)
103         {
104             TransactionImpl tx = getTransaction();
105             if(tx != null && tx.isOpen())
106             {
107                 pbKey = tx.getBroker().getPBKey();
108             }
109         }
110         return pbKey;
111     }
112 
113     protected void prepareForPersistency(PersistenceBroker broker)
114     {
115         if(oid == null)
116         {
117             if(realSubject == null)
118             {
119                 throw new OJBRuntimeException("Identity and real object are 'null' - Can not persist empty entry");
120             }
121             else
122             {
123                 oid = broker.serviceIdentity().buildIdentity(realSubject);
124             }
125         }
126     }
127 
128     protected void prepareRealSubject(PersistenceBroker broker)
129     {
130         if(oid == null)
131         {
132             throw new OJBRuntimeException("can not return real object, real object and Identity is null");
133         }
134         realSubject = broker.getObjectByIdentity(oid);
135     }
136 
137     public Object   getRealSubject()
138     {
139         if(realSubject != null)
140         {
141             return realSubject;
142         }
143         else
144         {
145             TransactionImpl tx = getTransaction();
146             if(tx != null && tx.isOpen())
147             {
148                 prepareRealSubject(tx.getBroker());
149                 if(realSubject != null)
150                 {
151                     RuntimeObject rt = new RuntimeObject(realSubject, tx, false);
152                     tx.lockAndRegister(rt, Transaction.READ, tx.getRegistrationList());
153                 }
154             }
155             else
156             {
157                 PBKey aPbKey = getPBKey();
158                 if(aPbKey != null)
159                 {
160                     PBCapsule capsule = new PBCapsule(aPbKey, null);
161                     try
162                     {
163                         prepareRealSubject(capsule.getBroker());
164                     }
165                     finally
166                     {
167                         capsule.destroy();
168                     }
169                 }
170                 else
171                 {
172                     getLog().warn("No tx, no PBKey - can't materialise object with Identity " + getOid());
173                 }
174             }
175         }
176         return realSubject;
177     }
178 
179     public void setRealSubject(Object   realSubject)
180     {
181         this.realSubject = realSubject;
182     }
183 
184     public int getPosition()
185     {
186         return position;
187     }
188 
189     public void setPosition(int newPosition)
190     {
191         position = newPosition;
192     }
193 
194     /**
195      * Gets the dlistId.
196      *
197      * @return Returns a int
198      */
199     public Integer   getDlistId()
200     {
201         return dlistId;
202     }
203 
204     /**
205      * Sets the dlistId.
206      *
207      * @param dlistId The dlistId to set
208      */
209     public void setDlistId(Integer   dlistId)
210     {
211         this.dlistId = dlistId;
212     }
213 
214     /**
215      * Gets the id.
216      *
217      * @return Returns a int
218      */
219     public Integer   getId()
220     {
221         return id;
222     }
223 
224     /**
225      * Sets the id.
226      *
227      * @param id The id to set
228      */
229     public void setId(Integer   id)
230     {
231         this.id = id;
232     }
233 
234     public Identity getOid()
235     {
236         return oid;
237     }
238 
239     public void setOid(Identity oid)
240     {
241         this.oid = oid;
242     }
243 
244     /**
245      * return String representation.
246      */
247     public String   toString()
248     {
249         ToStringBuilder buf = new ToStringBuilder(this);
250         buf.append("id", id);
251         buf.append("dListId", dlistId);
252         buf.append("position", position);
253         buf.append("identity", oid);
254         buf.append("realSubject", realSubject);
255         return buf.toString();
256     }
257 
258 
259     //===================================================
260     // PersistenceBrokerAware interface methods
261     //===================================================
262     public void beforeInsert(PersistenceBroker broker) throws PersistenceBrokerException
263     {
264         // before insert we have to build the Identity objects of the persistent objects
265         // we can't do this ealier, because we can now expect that the persistent object
266         // was written to DB (we make sure in code that the persistent object was locked before
267         // this entry) and the generated Identity is valid
268         prepareForPersistency(broker);
269     }
270 
271     public void beforeUpdate(PersistenceBroker broker) throws PersistenceBrokerException{}
272     public void beforeDelete(PersistenceBroker broker) throws PersistenceBrokerException{}
273     public void afterLookup(PersistenceBroker broker) throws PersistenceBrokerException{}
274     public void afterDelete(PersistenceBroker broker) throws PersistenceBrokerException{}
275     public void afterInsert(PersistenceBroker broker) throws PersistenceBrokerException{}
276     public void afterUpdate(PersistenceBroker broker) throws PersistenceBrokerException{}
277 }
278
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