1 //========================================================================
2 //Copyright 2005 Mort Bay Consulting Pty. Ltd.
3 //------------------------------------------------------------------------
4 //Licensed under the Apache License, Version 2.0 (the "License");
5 //you may not use this file except in compliance with the License.
6 //You may obtain a copy of the License at
7 //http://www.apache.org/licenses/LICENSE-2.0
8 //Unless required by applicable law or agreed to in writing, software
9 //distributed under the License is distributed on an "AS IS" BASIS,
10 //WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
11 //See the License for the specific language governing permissions and
12 //limitations under the License.
13 //========================================================================
14
15 package org.mortbay.component;
16 import java.util.EventListener;
17
18 import org.mortbay.log.Log;
19 import org.mortbay.util.LazyList;
20
21 /* ------------------------------------------------------------ */
22 /** Container.
23 * This class allows a containment events to be generated from update methods.
24 *
25 * The style of usage is: <pre>
26 * public void setFoo(Foo foo)
27 * {
28 * getContainer().update(this,this.foo,foo,"foo");
29 * this.foo=foo;
30 * }
31 *
32 * public void setBars(Bar[] bars)
33 * {
34 * getContainer().update(this,this.bars,bars,"bar");
35 * this.bars=bars;
36 * }
37 * </pre>
38 *
39 * @author gregw
40 *
41 */
42 public class Container
43 {
44 private Object _listeners;
45
46 public synchronized void addEventListener(Container.Listener listener)
47 {
48 _listeners=LazyList.add(_listeners,listener);
49 }
50
51 public synchronized void removeEventListener(Container.Listener listener)
52 {
53 _listeners=LazyList.remove(_listeners,listener);
54 }
55
56 /* ------------------------------------------------------------ */
57 /** Update single parent to child relationship.
58 * @param parent The parent of the child.
59 * @param oldChild The previous value of the child. If this is non null and differs from <code>child</code>, then a remove event is generated.
60 * @param child The current child. If this is non null and differs from <code>oldChild</code>, then an add event is generated.
61 * @param relationship The name of the relationship
62 */
63 public synchronized void update(Object parent, Object oldChild, final Object child, String relationship)
64 {
65 if (oldChild!=null && !oldChild.equals(child))
66 remove(parent,oldChild,relationship);
67 if (child!=null && !child.equals(oldChild))
68 add(parent,child,relationship);
69 }
70
71 /* ------------------------------------------------------------ */
72 /** Update single parent to child relationship.
73 * @param parent The parent of the child.
74 * @param oldChild The previous value of the child. If this is non null and differs from <code>child</code>, then a remove event is generated.
75 * @param child The current child. If this is non null and differs from <code>oldChild</code>, then an add event is generated.
76 * @param relationship The name of the relationship
77 * @param addRemoveBean If true add/remove is called for the new/old children as well as the relationships
78 */
79 public synchronized void update(Object parent, Object oldChild, final Object child, String relationship,boolean addRemove)
80 {
81 if (oldChild!=null && !oldChild.equals(child))
82 {
83 remove(parent,oldChild,relationship);
84 if (addRemove)
85 removeBean(oldChild);
86 }
87
88 if (child!=null && !child.equals(oldChild))
89 {
90 if (addRemove)
91 addBean(child);
92 add(parent,child,relationship);
93 }
94 }
95
96 /* ------------------------------------------------------------ */
97 /** Update multiple parent to child relationship.
98 * @param parent The parent of the child.
99 * @param oldChildren The previous array of children. A remove event is generated for any child in this array but not in the <code>children</code> array.
100 * This array is modified and children that remain in the new children array are nulled out of the old children array.
101 * @param children The current array of children. An add event is generated for any child in this array but not in the <code>oldChildren</code> array.
102 * @param relationship The name of the relationship
103 */
104 public synchronized void update(Object parent, Object[] oldChildren, final Object[] children, String relationship)
105 {
106 update(parent,oldChildren,children,relationship,false);
107 }
108
109 /* ------------------------------------------------------------ */
110 /** Update multiple parent to child relationship.
111 * @param parent The parent of the child.
112 * @param oldChildren The previous array of children. A remove event is generated for any child in this array but not in the <code>children</code> array.
113 * This array is modified and children that remain in the new children array are nulled out of the old children array.
114 * @param children The current array of children. An add event is generated for any child in this array but not in the <code>oldChildren</code> array.
115 * @param relationship The name of the relationship
116 * @param addRemoveBean If true add/remove is called for the new/old children as well as the relationships
117 */
118 public synchronized void update(Object parent, Object[] oldChildren, final Object[] children, String relationship, boolean addRemove)
119 {
120 Object[] newChildren = null;
121 if (children!=null)
122 {
123 newChildren = new Object[children.length];
124
125 for (int i=children.length;i-->0;)
126 {
127 boolean new_child=true;
128 if (oldChildren!=null)
129 {
130 for (int j=oldChildren.length;j-->0;)
131 {
132 if (children[i]!=null && children[i].equals(oldChildren[j]))
133 {
134 oldChildren[j]=null;
135 new_child=false;
136 }
137 }
138 }
139 if (new_child)
140 newChildren[i]=children[i];
141 }
142 }
143
144 if (oldChildren!=null)
145 {
146 for (int i=oldChildren.length;i-->0;)
147 {
148 if (oldChildren[i]!=null)
149 {
150 remove(parent,oldChildren[i],relationship);
151 if (addRemove)
152 removeBean(oldChildren[i]);
153 }
154 }
155 }
156
157 if (newChildren!=null)
158 {
159 for (int i=0;i<newChildren.length;i++)
160 if (newChildren[i]!=null)
161 {
162 if (addRemove)
163 addBean(newChildren[i]);
164 add(parent,newChildren[i],relationship);
165 }
166 }
167 }
168
169 /* ------------------------------------------------------------ */
170 public void addBean(Object obj)
171 {
172 if (_listeners!=null)
173 {
174 for (int i=0; i<LazyList.size(_listeners); i++)
175 {
176 Listener listener=(Listener)LazyList.get(_listeners, i);
177 listener.addBean(obj);
178 }
179 }
180 }
181
182 /* ------------------------------------------------------------ */
183 public void removeBean(Object obj)
184 {
185 if (_listeners!=null)
186 {
187 for (int i=0; i<LazyList.size(_listeners); i++)
188 ((Listener)LazyList.get(_listeners, i)).removeBean(obj);
189 }
190 }
191
192 /* ------------------------------------------------------------ */
193 /** Add a parent child relationship
194 * @param parent
195 * @param child
196 * @param relationship
197 */
198 private void add(Object parent, Object child, String relationship)
199 {
200 if (Log.isDebugEnabled())
201 Log.debug("Container "+parent+" + "+child+" as "+relationship);
202 if (_listeners!=null)
203 {
204 Relationship event=new Relationship(this,parent,child,relationship);
205 for (int i=0; i<LazyList.size(_listeners); i++)
206 ((Listener)LazyList.get(_listeners, i)).add(event);
207 }
208 }
209
210 /* ------------------------------------------------------------ */
211 /** remove a parent child relationship
212 * @param parent
213 * @param child
214 * @param relationship
215 */
216 private void remove(Object parent, Object child, String relationship)
217 {
218 if (Log.isDebugEnabled())
219 Log.debug("Container "+parent+" - "+child+" as "+relationship);
220 if (_listeners!=null)
221 {
222 Relationship event=new Relationship(this,parent,child,relationship);
223 for (int i=0; i<LazyList.size(_listeners); i++)
224 ((Listener)LazyList.get(_listeners, i)).remove(event);
225 }
226 }
227
228 /* ------------------------------------------------------------ */
229 /** A Container event.
230 * @see Listener
231 *
232 */
233 public static class Relationship
234 {
235 private Object _parent;
236 private Object _child;
237 private String _relationship;
238 private Container _container;
239
240 private Relationship(Container container, Object parent,Object child, String relationship)
241 {
242 _container=container;
243 _parent=parent;
244 _child=child;
245 _relationship=relationship;
246 }
247
248 public Container getContainer()
249 {
250 return _container;
251 }
252
253 public Object getChild()
254 {
255 return _child;
256 }
257
258 public Object getParent()
259 {
260 return _parent;
261 }
262
263 public String getRelationship()
264 {
265 return _relationship;
266 }
267
268 public String toString()
269 {
270 return _parent+"---"+_relationship+"-->"+_child;
271 }
272
273 public int hashCode()
274 {
275 return _parent.hashCode()+_child.hashCode()+_relationship.hashCode();
276 }
277
278 public boolean equals(Object o)
279 {
280 if (o==null || !(o instanceof Relationship))
281 return false;
282 Relationship r = (Relationship)o;
283 return r._parent==_parent && r._child==_child && r._relationship.equals(_relationship);
284 }
285 }
286
287 /* ------------------------------------------------------------ */
288 /** Listener.
289 * A listener for Container events.
290 */
291 public interface Listener extends EventListener
292 {
293 public void addBean(Object bean);
294 public void removeBean(Object bean);
295 public void add(Container.Relationship relationship);
296 public void remove(Container.Relationship relationship);
297
298 }
299 }