KickJava   Java API By Example, From Geeks To Geeks.

Java > Open Source Codes > org > apache > ojb > broker > util > collections > RemovalAwareList


1 package org.apache.ojb.broker.util.collections;
2
3 /* Copyright 2004-2005 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 org.apache.ojb.broker.PersistenceBroker;
19 import org.apache.ojb.broker.PersistenceBrokerException;
20
21 import java.util.Iterator JavaDoc;
22 import java.util.Vector JavaDoc;
23
24 /**
25  * This is a list that tracks removal and addition of elements.
26  * This tracking allow the PersistenceBroker to delete elements from
27  * the database that have been removed from the collection before a
28  * PB.store() orperation occurs.
29  * This will allow to use the PB api in way pretty close to ODMG persistent
30  * collections!
31  * @author Thomas Mahler, adapted to ManageableArrayList by Edson C. E. Richter
32  * @version $Id: RemovalAwareList.java,v 1.4.2.1 2005/12/21 22:28:15 tomdz Exp $
33  */
34 public class RemovalAwareList extends ManageableArrayList implements IRemovalAwareCollection
35 {
36     private Vector JavaDoc allObjectsToBeRemoved = new Vector JavaDoc();
37
38     /**
39      * @see org.apache.ojb.broker.ManageableCollection#afterStore(PersistenceBroker broker)
40      */
41     public void afterStore(PersistenceBroker broker) throws PersistenceBrokerException
42     {
43         // make sure allObjectsToBeRemoved does not contain
44 // any instances that got re-added to the list
45 allObjectsToBeRemoved.removeAll(this);
46
47         Iterator JavaDoc iter = allObjectsToBeRemoved.iterator();
48         while (iter.hasNext())
49         {
50             broker.delete(iter.next());
51         }
52         allObjectsToBeRemoved.clear();
53     }
54
55     /**
56      * @see java.util.List#remove(int)
57      */
58     public Object JavaDoc remove(int index)
59     {
60         Object JavaDoc toBeRemoved = super.remove(index);
61         registerForDeletion(toBeRemoved);
62         return toBeRemoved;
63     }
64
65     protected void registerForDeletion(Object JavaDoc toBeRemoved)
66     {
67         //only add objects once to avoid double deletions
68 if (!allObjectsToBeRemoved.contains(toBeRemoved))
69         {
70             this.allObjectsToBeRemoved.add(toBeRemoved);
71         }
72     }
73
74     /**
75      * @see java.util.Collection#remove(Object)
76      */
77     public boolean remove(Object JavaDoc o)
78     {
79         boolean result = super.remove(o);
80         registerForDeletion(o);
81         return result;
82     }
83
84     /**
85      * @see java.util.Vector#removeAllElements()
86      */
87     public synchronized void removeAllElements()
88     {
89         for (int i = 0; i < this.size(); i++)
90         {
91             registerForDeletion(this.get(i));
92         }
93         super.clear();
94     }
95
96
97     /**
98      * @see java.util.Vector#removeElementAt(int)
99      */
100     public synchronized void removeElementAt(int index)
101     {
102         Object JavaDoc toBeDeleted = this.get(index);
103         registerForDeletion(toBeDeleted);
104         super.remove(index);
105     }
106
107     public synchronized void clear() {
108       removeAllElements();
109     }
110     
111     /**
112      * @see java.util.AbstractList#removeRange(int, int)
113      */
114     protected void removeRange(int fromIndex, int toIndex)
115     {
116         for (int i = fromIndex; i < toIndex; i++)
117         {
118             registerForDeletion(this.get(i));
119         }
120         super.removeRange(fromIndex, toIndex);
121     }
122
123     public void resetDeleted() {
124       this.allObjectsToBeRemoved.clear();
125     }
126     
127 }
128
Popular Tags