WMObject


1   package de.webman.acl;
2   
3   import com.teamkonzept.lib.TKException;
4   import com.teamkonzept.lib.TKVector;
5   import de.webman.acl.db.ObjectDBData;
6   
7   /**
8    * Base class of persistent objects. Provides a means for identification
9    * throughout the object system as well as the database system. Creation of
10   * such objects should be left to a corresponding factory to ensure uniqueness.
11   *
12   * @author  $Author: mischa $
13   * @version $Revision: 1.1 $
14   */
15  public abstract class WMObject
16  {
17  
18      // $Header: /cvsroot/webman-cms/source/webman/de/webman/acl/WMObject.java,v 1.1 2001/08/20 08:25:07 mischa Exp $
19  
20      // Attributes
21  
22      /**
23       * Specifies wether at least one of the attributes has been modified.
24       */
25      private boolean attributesModified = false;
26  
27      /**
28       * Specifies wether at least one of the associations has been modified.
29       */
30      private boolean associationsModified = false;
31  
32      /**
33       * Specifies wether the associations has been loaded.
34       */
35      private boolean associationsLoaded = false;
36  
37      /**
38       * The ID of the persistent object.
39       */
40      private Integer   id = null;
41  
42      /**
43       * The string representation of the persistent object.
44       */
45      private String   string = null;
46  
47      /**
48       * The IDs of the associated persistent objects.
49       */
50      private TKVector associations = null;
51  
52  
53      // Constructors
54  
55      /**
56       * Provide instantion only to package classes or subclasses.
57       *
58       * @param data the initial object data.
59       */
60      protected WMObject (ObjectDBData data)
61      {
62          this.id = data.getID();
63      }
64  
65  
66      // Standard methods
67  
68      /**
69       * Checks wether the persistent and the given object can be treated as equal.
70       *
71       * @param object the object to be proved upon equality.
72       * @return <CODE>true</CODE> if both objects can be treated as equal,
73       * otherwise <CODE>false</CODE>.
74       */
75      public final boolean equals (Object   object)
76      {
77          if (object == null)
78          {
79              return false;
80          }
81  
82          if (object.getClass() != getClass())
83          {
84              return false;
85          }
86  
87          return ((WMObject) object).getID().equals(this.id);
88      }
89  
90      /**
91       * Returns the hash code of the persistent object.
92       *
93       * @return the hash code of the persistent object.
94       */
95      public final int hashCode ()
96      {
97          return this.id.intValue();
98      }
99  
100     /**
101      * Returns the string representation of the persistent object.
102      *
103      * @return the string representation of the persistent object.
104      */
105     public final String   toString ()
106     {
107         if (this.string == null)
108         {
109             this.string = (new StringBuffer  (getClass().getName())).append('.')
110                                                                   .append(id)
111                                                                   .toString();
112         }
113 
114         return this.string;
115     }
116 
117 
118     // Method signatures
119 
120     /**
121      * Returns the factory of the object.
122      *
123      * @return the factory of the object.
124      * @exception com.teamkonzept.lib.TKException if an error occured during factory retrieval.
125      */
126     public abstract ObjectFactory getFactory ()
127         throws TKException;
128 
129 
130     // Method implementations
131 
132     /**
133      * Returns the ID of the persistent object.
134      *
135      * @return the ID of the persistent object.
136      */
137     public final Integer   getID ()
138     {
139         return id;
140     }
141 
142     /**
143      * Checks wether at least one of the attributes has been modified.
144      *
145      * @return <CODE>true</CODE> at least one of the attributes has been
146      * modified, otherwise <CODE>false</CODE>.
147      */
148     public final boolean isModifiedAttributes ()
149     {
150         return this.attributesModified;
151     }
152 
153     /**
154      * Checks wether at least one of the associations has been modified.
155      *
156      * @return <CODE>true</CODE> at least one of the associations has been
157      * modified, otherwise <CODE>false</CODE>.
158      */
159     public final boolean isModifiedAssociations ()
160     {
161         return this.associationsModified;
162     }
163 
164 
165     // Attribute handling methods
166 
167     /**
168      * Informs the object about the modification of one of its attributes.
169      *
170      * @param pre the value of the attribute before the modification.
171      * @param post the value of the attribute after the modification.
172      */
173     protected final void modifyAttribute (Object   pre, Object   post)
174     {
175         if (pre != null || post != null)
176         {
177             try
178             {
179                 this.attributesModified = this.attributesModified ||
180                                           ! pre.equals(post);
181             }
182             catch (NullPointerException   npe)
183             {
184                 this.attributesModified = true;
185             }
186         }
187     }
188 
189     /**
190      * Informs the object about the succesful update of its attributes.
191      */
192     protected final void updatedAttributes ()
193     {
194         this.attributesModified = false;
195     }
196 
197 
198     // Association handling methods
199 
200     /**
201      * Returns the IDs of all associated objects.
202      *
203      * @return the IDs of all associated objects.
204      * @exception com.teamkonzept.lib.TKException if an error occured during object retrieval.
205      */
206     protected final TKVector getAssociations ()
207         throws TKException
208     {
209         loadAssociations();
210 
211         return this.associations;
212     }
213 
214     /**
215      * Adds an association with the given object.
216      *
217      * @param object the object.
218      * @exception com.teamkonzept.lib.TKException if an error occured during object retrieval.
219      */
220     protected final void addAssociation (WMObject object)
221         throws TKException
222     {
223         loadAssociations();
224 
225         if (object != null)
226         {
227             if (this.associations == null)
228             {
229                 this.associations = new TKVector();
230             }
231 
232             if (! this.associations.contains(object.getID()))
233             {
234                 this.associations.addElement(object.getID());
235                 this.associationsModified = true;
236             }
237         }
238     }
239 
240     /**
241      * Removes the association with the given object.
242      *
243      * @param object the object.
244      * @exception com.teamkonzept.lib.TKException if an error occured during object retrieval.
245      */
246     protected final void removeAssociation (WMObject object)
247         throws TKException
248     {
249         loadAssociations();
250 
251         if (object != null &&
252             this.associations != null)
253         {
254             this.associationsModified = this.associationsModified ||
255                                         this.associations.removeElement(object.getID());
256         }
257     }
258 
259     /**
260      * Removes the association with all objects.
261      *
262      * @exception com.teamkonzept.lib.TKException if an error occured during object retrieval.
263      */
264     protected final void removeAssociations ()
265         throws TKException
266     {
267         loadAssociations();
268 
269         if (this.associations != null &&
270             this.associations.size() > 0)
271         {
272             this.associations.removeAllElements();
273             this.associationsModified = true;
274         }
275     }
276 
277     /**
278      * Checks wether there is an association with the given object.
279      *
280      * @param object the object.
281      * @return <CODE>true</CODE> if there is an association with the
282      * given object, otherwise <CODE>false</CODE>.
283      * @exception com.teamkonzept.lib.TKException if an error occured during object retrieval.
284      */
285     protected final boolean containsAssociation (WMObject object)
286         throws TKException
287     {
288         loadAssociations();
289 
290         if (object != null &&
291             this.associations != null)
292         {
293             return this.associations.contains(object.getID());
294         }
295 
296         return false;
297     }
298 
299     /**
300      * Informs the object about the succesful update of its associations.
301      */
302     protected final void updatedAssociations ()
303     {
304         this.associationsModified = false;
305     }
306 
307     /**
308      * Loads the associations on demand.
309      *
310      * @exception com.teamkonzept.lib.TKException if an error occured during object retrieval.
311      */
312     protected final void loadAssociations ()
313         throws TKException
314     {
315         if (! this.associationsLoaded)
316         {
317             this.associations = getFactory().getObjectAssociations(this);
318             this.associationsLoaded = true;
319         }
320     }
321 
322 }
323
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