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Java > Open Source Codes > org > roller > pojos > HierarchicalPersistentObject


1 /*
2  * Created on Jan 13, 2004
3  */
4 package org.roller.pojos;
5
6 import org.roller.RollerException;
7 import org.roller.business.PersistenceStrategy;
8 import org.roller.model.RollerFactory;
9
10 import java.util.Iterator JavaDoc;
11 import java.util.LinkedList JavaDoc;
12 import java.util.List JavaDoc;
13
14 /**
15  * Abstract base class for hierarchical persistent objects. Provides generic
16  * implementations of save and remove that know how to handle parents, children,
17  * and descendents.
18  *
19  * @author David M Johnson
20  */
21 public abstract class HierarchicalPersistentObject extends PersistentObject
22 {
23     protected HierarchicalPersistentObject mNewParent = null;
24     
25     /** Create an association between object and ancestor. */
26     protected abstract Assoc createAssoc(
27         HierarchicalPersistentObject object,
28         HierarchicalPersistentObject ancestor,
29         String JavaDoc relation ) throws RollerException;
30         
31     /** Name of association class which must implement Assoc. */
32     public abstract Class JavaDoc getAssocClass();
33     
34     /** Name of object propery in association class */
35     public abstract String JavaDoc getObjectPropertyName();
36     
37     /** Name of ancestor propery in association class */
38     public abstract String JavaDoc getAncestorPropertyName();
39     
40     /** Set new parent - invalidates getPath() until object is saved(). */
41     public abstract void setParent(HierarchicalPersistentObject parent);
42     
43     protected abstract Assoc getParentAssoc() throws RollerException;
44
45     protected abstract List JavaDoc getChildAssocs() throws RollerException;
46     
47     public abstract List JavaDoc getAllDescendentAssocs() throws RollerException;
48     
49     public abstract List JavaDoc getAncestorAssocs() throws RollerException;
50     
51     /** Returns true if this object is in use and should not be deleted */
52     public abstract boolean isInUse() throws RollerException;
53
54     /** Save this object and ancestoral associations. */
55     public void save() throws RollerException
56     {
57         boolean fresh = (getId() == null || "".equals(getId()));
58         PersistenceStrategy pstrategy =
59             RollerFactory.getRoller().getPersistenceStrategy();
60         pstrategy.store(this);
61         if (fresh)
62         {
63             // Every fresh cat needs a parent assoc
64 Assoc parentAssoc = createAssoc(
65                 this, mNewParent, Assoc.PARENT);
66             parentAssoc.save();
67         }
68         else if (null != mNewParent)
69         {
70             // New parent must be added to parentAssoc
71 Assoc parentAssoc = getParentAssoc();
72             parentAssoc.setAncestor(mNewParent);
73             parentAssoc.save();
74         }
75         
76         // Clear out existing grandparent associations
77 Iterator JavaDoc ancestors = getAncestorAssocs().iterator();
78         while (ancestors.hasNext())
79         {
80             Assoc assoc = (Assoc)ancestors.next();
81             if (assoc.getRelation().equals(Assoc.GRANDPARENT))
82             {
83                 assoc.remove();
84             }
85         }
86         
87         // Walk parent assocations, creating new grandparent associations
88 int count = 0;
89         Assoc currentAssoc = getParentAssoc();
90         while (null != currentAssoc.getAncestor())
91         {
92             if (count > 0)
93             {
94                 Assoc assoc = createAssoc(this,
95                     currentAssoc.getAncestor(),
96                     Assoc.GRANDPARENT);
97                 assoc.save();
98             }
99             currentAssoc = currentAssoc.getAncestor().getParentAssoc();
100             count++;
101         }
102         
103         // all descendents must also reset their ancestor links
104 // Query childQuery =
105 // pstrategy.getQueryFactory().createQuery(getAssocClass());
106 // childQuery.setWhere(
107 // pstrategy.getQueryFactory().createCondition(
108 // pstrategy.getQueryFactory().createCondition(
109 // getAncestorPropertyName(), Query.EQ, this),
110 // Query.AND,
111 // pstrategy.getQueryFactory().createCondition(
112 // "relation", Query.EQ, Assoc.PARENT)));
113 //
114 Iterator JavaDoc children = getChildAssocs().iterator();
115         while (children.hasNext())
116         {
117             Assoc assoc = (Assoc) children.next();
118             
119             // resetting parent will cause reset of ancestors links
120 assoc.getObject().setParent(this);
121             
122             // recursively...
123 assoc.getObject().save();
124         }
125         
126         // Clear new parent now that new parent has been saved
127 mNewParent = null;
128     }
129
130
131     /** Remove self, all decendent children and associations. */
132     public void remove() throws RollerException
133     {
134         PersistenceStrategy pstrategy =
135             RollerFactory.getRoller().getPersistenceStrategy();
136
137         // loop to remove all of my descendents and associations
138 List JavaDoc toRemove = new LinkedList JavaDoc();
139         Iterator JavaDoc catIter = this.getAllDescendentAssocs().iterator();
140         while (catIter.hasNext())
141         {
142             Assoc assoc = (Assoc)catIter.next();
143             HierarchicalPersistentObject hpo = assoc.getObject();
144             
145             // remove my descendent's parent and grandparent associations
146 Iterator JavaDoc ancestors = hpo.getAncestorAssocs().iterator();
147             while (ancestors.hasNext())
148             {
149                 Assoc dassoc = (Assoc)ancestors.next();
150                 dassoc.remove();
151             }
152             
153             // remove decendent association and descendents
154 assoc.remove();
155             toRemove.add(hpo);
156         }
157         Iterator JavaDoc removeIterator = toRemove.iterator();
158         while (removeIterator.hasNext())
159         {
160             PersistentObject po = (PersistentObject) removeIterator.next();
161             removeDescendent(pstrategy, po);
162         }
163
164         // loop to remove my own parent and grandparent associations
165 Iterator JavaDoc ancestors = getAncestorAssocs().iterator();
166         while (ancestors.hasNext())
167         {
168             Assoc assoc = (Assoc)ancestors.next();
169             assoc.remove();
170         }
171         
172         // remove myself
173 removeDescendent(pstrategy, this);
174     }
175
176     /**
177      * Override this if you want to handle descendant removal yourself.
178      */
179     protected void removeDescendent(
180        PersistenceStrategy pstrategy, PersistentObject po) throws RollerException
181     {
182         pstrategy.remove(po);
183     }
184
185     /** Should be needed only be manager objects */
186     public HierarchicalPersistentObject getNewParent()
187     {
188         return mNewParent;
189     }
190     
191 // /** Query database to get parent association. */
192 // protected Assoc getParentAssoc()
193 // throws RollerException
194 // {
195 // Class clazz = getAssocClass();
196 // String objectColName = getObjectPropertyName();
197 //
198 // QueryFactory factory =
199 // RollerFactory.getRoller().getPersistenceStrategy().getQueryFactory();
200 // Query query = factory.createQuery(clazz);
201 //
202 // Condition catCond =
203 // factory.createCondition(objectColName, Query.EQ, this);
204 // Condition parentCond =
205 // factory.createCondition("relation",Query.EQ,Assoc.PARENT);
206 // query.setWhere(factory.createCondition(catCond, Query.AND, parentCond));
207 // List parents = query.execute();
208 //
209 // if (parents.size() > 1)
210 // {
211 // throw new RollerException("ERROR: more than one parent");
212 // }
213 // else if (parents.size() == 1)
214 // {
215 // return (Assoc) parents.get(0);
216 // }
217 // else
218 // {
219 // return null;
220 // }
221 // }
222 //
223 // /** Get child associations, those whose parent is this category. */
224 // protected List getChildAssocs()
225 // throws RollerException
226 // {
227 // Class clazz = getAssocClass();
228 // String assocColName = getAncestorPropertyName();
229 //
230 // QueryFactory factory =
231 // RollerFactory
232 // .getRoller()
233 // .getPersistenceStrategy()
234 // .getQueryFactory();
235 // Query query = factory.createQuery(clazz);
236 //
237 // Condition catCond =
238 // factory.createCondition(assocColName, Query.EQ, this);
239 //
240 // Condition parentCond =
241 // factory.createCondition("relation", Query.EQ, Assoc.PARENT);
242 //
243 // query.setWhere(factory.createCondition(catCond, Query.AND, parentCond));
244 // return query.execute();
245 // }
246 //
247 // /**
248 // * Get all descendent associations, those that have this category as an
249 // * ancestor, public for testing purposes only.
250 // */
251 // public List getAllDescendentAssocs()
252 // throws RollerException
253 // {
254 // Class clazz = getAssocClass();
255 // String assocColName = getAncestorPropertyName();
256 // QueryFactory factory =
257 // RollerFactory.getRoller().getPersistenceStrategy().getQueryFactory();
258 // Query query = factory.createQuery(clazz);
259 // query.setWhere(factory.createCondition(assocColName, Query.EQ, this));
260 // return query.execute();
261 // }
262 //
263 // /**
264 // * Get all ancestor associations, public for testing purposes only.
265 // */
266 // public List getAncestorAssocs()
267 // throws RollerException
268 // {
269 // Class clazz = getAssocClass();
270 // String objectColName = getObjectPropertyName();
271 // QueryFactory factory =
272 // RollerFactory.getRoller().getPersistenceStrategy().getQueryFactory();
273 // Query query = factory.createQuery(clazz);
274 // query.setWhere(factory.createCondition(objectColName, Query.EQ, this));
275 // return query.execute();
276 // }
277 }
278
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