TableModificationEvent


1   /**
2    * com.mckoi.database.TableModificationEvent  07 Mar 2003
3    *
4    * Mckoi SQL Database ( http://www.mckoi.com/database )
5    * Copyright (C) 2000, 2001, 2002  Diehl and Associates, Inc.
6    *
7    * This program is free software; you can redistribute it and/or
8    * modify it under the terms of the GNU General Public License
9    * Version 2 as published by the Free Software Foundation.
10   *
11   * This program is distributed in the hope that it will be useful,
12   * but WITHOUT ANY WARRANTY; without even the implied warranty of
13   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14   * GNU General Public License Version 2 for more details.
15   *
16   * You should have received a copy of the GNU General Public License
17   * Version 2 along with this program; if not, write to the Free Software
18   * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
19   *
20   * Change Log:
21   * 
22   * 
23   */
24  
25  package com.mckoi.database;
26  
27  /**
28   * The event information of when a table is modified inside a transaction.
29   *
30   * @author Tobias Downer
31   */
32  
33  public class TableModificationEvent {
34  
35    // ----- Statics -----
36  
37    /**
38     * Event that occurs before the action
39     */
40    public static final int BEFORE = 0x010;
41  
42    /**
43     * Event that occurs after the action
44     */
45    public static final int AFTER = 0x020;
46  
47    // ---
48  
49    /**
50     * Event type for insert action.
51     */
52    public static final int INSERT = 0x001;
53  
54    /**
55     * Event type for update action.
56     */
57    public static final int UPDATE = 0x002;
58  
59    /**
60     * Event type for delete action.
61     */
62    public static final int DELETE = 0x004;
63  
64    // ---
65  
66    /**
67     * Event for before an insert.
68     */
69    public static final int BEFORE_INSERT = BEFORE | INSERT;
70  
71    /**
72     * Event for after an insert.
73     */
74    public static final int AFTER_INSERT = AFTER | INSERT;
75  
76    /**
77     * Event for before an update.
78     */
79    public static final int BEFORE_UPDATE = BEFORE | UPDATE;
80  
81    /**
82     * Event for after an update.
83     */
84    public static final int AFTER_UPDATE = AFTER | UPDATE;
85  
86    /**
87     * Event for before a delete.
88     */
89    public static final int BEFORE_DELETE = BEFORE | DELETE;
90  
91    /**
92     * Event for after a delete.
93     */
94    public static final int AFTER_DELETE = AFTER | DELETE;
95  
96  
97    // ----- Members -----
98  
99    /**
100    * The DatabaseConnection of the table that the modification occurred in.
101    */
102   private DatabaseConnection connection;
103 
104   /**
105    * The name of the table that was modified.
106    */
107   private TableName table_name;
108 
109   /**
110    * The type of event that occurred.
111    */
112   private int event_type;
113 
114   /**
115    * A RowData object representing the row that is being inserted by this
116    * modification.  This is set for INSERT and UPDATE events.  If the event
117    * type is BEFORE then this data represents the new data in the table and
118    * can be modified.  This represents the NEW information.
119    */
120   private RowData row_data;
121 
122   /**
123    * The row index of the table that is before removed by this modification.
124    * This is set for UPDATE and DELETE events.  This represents the OLD
125    * information.
126    */
127   private int row_index = -1;
128 
129   /**
130    * General Constructor.
131    */
132   private TableModificationEvent(DatabaseConnection connection,
133          TableName table_name, int row_index, RowData row_data,
134          int type, boolean before) {
135     this.connection = connection;
136     this.table_name = table_name;
137     this.row_index = row_index;
138     this.row_data = row_data;
139     this.event_type = type | (before ? BEFORE : AFTER);
140   }
141 
142   /**
143    * Constructs an insert event.
144    */
145   TableModificationEvent(DatabaseConnection connection, TableName table_name,
146                          RowData row_data, boolean before) {
147     this(connection, table_name, -1, row_data, INSERT, before);
148   }
149 
150   /**
151    * Constructs an update event.
152    */
153   TableModificationEvent(DatabaseConnection connection, TableName table_name,
154                          int row_index, RowData row_data, boolean before) {
155     this(connection, table_name, row_index, row_data, UPDATE, before);
156   }
157 
158   /**
159    * Constructs a delete event.
160    */
161   TableModificationEvent(DatabaseConnection connection, TableName table_name,
162                          int row_index, boolean before) {
163     this(connection, table_name, row_index, null, DELETE, before);
164   }
165 
166   /**
167    * Returns the DatabaseConnection that this event fired in.
168    */
169   public DatabaseConnection getDatabaseConnection() {
170     return connection;
171   }
172 
173   /**
174    * Returns the event type.
175    */
176   public int getType() {
177     return event_type;
178   }
179 
180   /**
181    * Returns true if this is a BEFORE event.
182    */
183   public boolean isBefore() {
184     return (event_type & BEFORE) != 0;
185   }
186   
187   /**
188    * Returns true if this is a AFTER event.
189    */
190   public boolean isAfter() {
191     return (event_type & AFTER) != 0;
192   }
193   
194   /**
195    * Returns true if this is an INSERT event.
196    */
197   public boolean isInsert() {
198     return (event_type & INSERT) != 0;
199   }
200 
201   /**
202    * Returns true if this is an UPDATE event.
203    */
204   public boolean isUpdate() {
205     return (event_type & UPDATE) != 0;
206   }
207 
208   /**
209    * Returns true if this is an DELETE event.
210    */
211   public boolean isDelete() {
212     return (event_type & DELETE) != 0;
213   }
214 
215   /**
216    * Returns the name of the table of this modification.
217    */
218   public TableName getTableName() {
219     return table_name;
220   }
221 
222   /**
223    * Returns the index of the row in the table that was affected by this
224    * event or -1 if event type is INSERT.
225    */
226   public int getRowIndex() {
227     return row_index;
228   }
229 
230   /**
231    * Returns the RowData object that represents the change that is being
232    * made to the table either by an INSERT or UPDATE.  For a DELETE event this
233    * return null.
234    */
235   public RowData getRowData() {
236     return row_data;
237   }
238 
239   /**
240    * Returns true if the given listener type should be notified of this type
241    * of table modification event.  For example, if this is a BEFORE event then
242    * the BEFORE bit on the given type must be set and if this is an INSERT event
243    * then the INSERT bit on the given type must be set.
244    */
245   public boolean listenedBy(int listen_t) {
246     // If this is a BEFORE trigger, then we must be listening for BEFORE events,
247     // etc.
248     boolean ba_match =
249        ( (event_type & BEFORE) != 0 && (listen_t & BEFORE) != 0 ) ||
250        ( (event_type & AFTER) != 0 && (listen_t & AFTER) != 0 );
251     // If this is an INSERT trigger, then we must be listening for INSERT
252     // events, etc.
253     boolean trig_match =
254        ( (event_type & INSERT) != 0 && (listen_t & INSERT) != 0 ) ||
255        ( (event_type & DELETE) != 0 && (listen_t & DELETE) != 0 ) ||
256        ( (event_type & UPDATE) != 0 && (listen_t & UPDATE) != 0 );
257     // If both of the above are true
258     return (ba_match && trig_match);
259   }
260   
261 }
262 
263
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