1 // ========================================================================
2 // Copyright (c) 2005-2009 Mort Bay Consulting Pty. Ltd.
3 // ------------------------------------------------------------------------
4 // All rights reserved. This program and the accompanying materials
5 // are made available under the terms of the Eclipse Public License v1.0
6 // and Apache License v2.0 which accompanies this distribution.
7 // The Eclipse Public License is available at
8 // http://www.eclipse.org/legal/epl-v10.html
9 // The Apache License v2.0 is available at
10 // http://www.opensource.org/licenses/apache2.0.php
11 // You may elect to redistribute this code under either of these licenses.
12 // ========================================================================
13
14 package org.eclipse.jetty.util.component;
15 import java.util.EventListener;
16 import java.util.concurrent.CopyOnWriteArrayList;
17
18 import org.eclipse.jetty.util.LazyList;
19 import org.eclipse.jetty.util.log.Log;
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 public class Container
40 {
41 private final CopyOnWriteArrayList<Container.Listener> _listeners=new CopyOnWriteArrayList<Container.Listener>();
42
43 public void addEventListener(Container.Listener listener)
44 {
45 _listeners.add(listener);
46 }
47
48 public void removeEventListener(Container.Listener listener)
49 {
50 _listeners.remove(listener);
51 }
52
53 /* ------------------------------------------------------------ */
54 /** Update single parent to child relationship.
55 * @param parent The parent of the child.
56 * @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.
57 * @param child The current child. If this is non null and differs from <code>oldChild</code>, then an add event is generated.
58 * @param relationship The name of the relationship
59 */
60 public void update(Object parent, Object oldChild, final Object child, String relationship)
61 {
62 if (oldChild!=null && !oldChild.equals(child))
63 remove(parent,oldChild,relationship);
64 if (child!=null && !child.equals(oldChild))
65 add(parent,child,relationship);
66 }
67
68 /* ------------------------------------------------------------ */
69 /** Update single parent to child relationship.
70 * @param parent The parent of the child.
71 * @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.
72 * @param child The current child. If this is non null and differs from <code>oldChild</code>, then an add event is generated.
73 * @param relationship The name of the relationship
74 * @param addRemove If true add/remove is called for the new/old children as well as the relationships
75 */
76 public void update(Object parent, Object oldChild, final Object child, String relationship,boolean addRemove)
77 {
78 if (oldChild!=null && !oldChild.equals(child))
79 {
80 remove(parent,oldChild,relationship);
81 if (addRemove)
82 removeBean(oldChild);
83 }
84
85 if (child!=null && !child.equals(oldChild))
86 {
87 if (addRemove)
88 addBean(child);
89 add(parent,child,relationship);
90 }
91 }
92
93 /* ------------------------------------------------------------ */
94 /** Update multiple parent to child relationship.
95 * @param parent The parent of the child.
96 * @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.
97 * This array is modified and children that remain in the new children array are nulled out of the old children array.
98 * @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.
99 * @param relationship The name of the relationship
100 */
101 public void update(Object parent, Object[] oldChildren, final Object[] children, String relationship)
102 {
103 update(parent,oldChildren,children,relationship,false);
104 }
105
106 /* ------------------------------------------------------------ */
107 /** Update multiple parent to child relationship.
108 * @param parent The parent of the child.
109 * @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.
110 * This array is modified and children that remain in the new children array are nulled out of the old children array.
111 * @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.
112 * @param relationship The name of the relationship
113 * @param addRemove If true add/remove is called for the new/old children as well as the relationships
114 */
115 public void update(Object parent, Object[] oldChildren, final Object[] children, String relationship, boolean addRemove)
116 {
117 Object[] newChildren = null;
118 if (children!=null)
119 {
120 newChildren = new Object[children.length];
121
122 for (int i=children.length;i-->0;)
123 {
124 boolean new_child=true;
125 if (oldChildren!=null)
126 {
127 for (int j=oldChildren.length;j-->0;)
128 {
129 if (children[i]!=null && children[i].equals(oldChildren[j]))
130 {
131 oldChildren[j]=null;
132 new_child=false;
133 }
134 }
135 }
136 if (new_child)
137 newChildren[i]=children[i];
138 }
139 }
140
141 if (oldChildren!=null)
142 {
143 for (int i=oldChildren.length;i-->0;)
144 {
145 if (oldChildren[i]!=null)
146 {
147 remove(parent,oldChildren[i],relationship);
148 if (addRemove)
149 removeBean(oldChildren[i]);
150 }
151 }
152 }
153
154 if (newChildren!=null)
155 {
156 for (int i=0;i<newChildren.length;i++)
157 if (newChildren[i]!=null)
158 {
159 if (addRemove)
160 addBean(newChildren[i]);
161 add(parent,newChildren[i],relationship);
162 }
163 }
164 }
165
166 /* ------------------------------------------------------------ */
167 public void addBean(Object obj)
168 {
169 if (_listeners!=null)
170 {
171 for (int i=0; i<LazyList.size(_listeners); i++)
172 {
173 Listener listener=(Listener)LazyList.get(_listeners, i);
174 listener.addBean(obj);
175 }
176 }
177 }
178
179 /* ------------------------------------------------------------ */
180 public void removeBean(Object obj)
181 {
182 if (_listeners!=null)
183 {
184 for (int i=0; i<LazyList.size(_listeners); i++)
185 ((Listener)LazyList.get(_listeners, i)).removeBean(obj);
186 }
187 }
188
189 /* ------------------------------------------------------------ */
190 /** Add a parent child relationship
191 * @param parent
192 * @param child
193 * @param relationship
194 */
195 private void add(Object parent, Object child, String relationship)
196 {
197 if (Log.isDebugEnabled())
198 Log.debug("Container "+parent+" + "+child+" as "+relationship);
199 if (_listeners!=null)
200 {
201 Relationship event=new Relationship(this,parent,child,relationship);
202 for (int i=0; i<LazyList.size(_listeners); i++)
203 ((Listener)LazyList.get(_listeners, i)).add(event);
204 }
205 }
206
207 /* ------------------------------------------------------------ */
208 /** remove a parent child relationship
209 * @param parent
210 * @param child
211 * @param relationship
212 */
213 private void remove(Object parent, Object child, String relationship)
214 {
215 if (Log.isDebugEnabled())
216 Log.debug("Container "+parent+" - "+child+" as "+relationship);
217 if (_listeners!=null)
218 {
219 Relationship event=new Relationship(this,parent,child,relationship);
220 for (int i=0; i<LazyList.size(_listeners); i++)
221 ((Listener)LazyList.get(_listeners, i)).remove(event);
222 }
223 }
224
225 /* ------------------------------------------------------------ */
226 /** A Container event.
227 * @see Listener
228 *
229 */
230 public static class Relationship
231 {
232 private Object _parent;
233 private Object _child;
234 private String _relationship;
235 private Container _container;
236
237 private Relationship(Container container, Object parent,Object child, String relationship)
238 {
239 _container=container;
240 _parent=parent;
241 _child=child;
242 _relationship=relationship;
243 }
244
245 public Container getContainer()
246 {
247 return _container;
248 }
249
250 public Object getChild()
251 {
252 return _child;
253 }
254
255 public Object getParent()
256 {
257 return _parent;
258 }
259
260 public String getRelationship()
261 {
262 return _relationship;
263 }
264
265 @Override
266 public String toString()
267 {
268 return _parent+"---"+_relationship+"-->"+_child;
269 }
270
271 @Override
272 public int hashCode()
273 {
274 return _parent.hashCode()+_child.hashCode()+_relationship.hashCode();
275 }
276
277 @Override
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 }