1 //
2 // ========================================================================
3 // Copyright (c) 1995-2013 Mort Bay Consulting Pty. Ltd.
4 // ------------------------------------------------------------------------
5 // All rights reserved. This program and the accompanying materials
6 // are made available under the terms of the Eclipse Public License v1.0
7 // and Apache License v2.0 which accompanies this distribution.
8 //
9 // The Eclipse Public License is available at
10 // http://www.eclipse.org/legal/epl-v10.html
11 //
12 // The Apache License v2.0 is available at
13 // http://www.opensource.org/licenses/apache2.0.php
14 //
15 // You may elect to redistribute this code under either of these licenses.
16 // ========================================================================
17 //
18
19 package org.eclipse.jetty.util.component;
20 import java.lang.ref.WeakReference;
21 import java.util.EventListener;
22 import java.util.concurrent.CopyOnWriteArrayList;
23
24 import org.eclipse.jetty.util.LazyList;
25 import org.eclipse.jetty.util.log.Log;
26 import org.eclipse.jetty.util.log.Logger;
27
28 /* ------------------------------------------------------------ */
29 /** Container.
30 * This class allows a containment events to be generated from update methods.
31 *
32 * The style of usage is: <pre>
33 * public void setFoo(Foo foo)
34 * {
35 * getContainer().update(this,this.foo,foo,"foo");
36 * this.foo=foo;
37 * }
38 *
39 * public void setBars(Bar[] bars)
40 * {
41 * getContainer().update(this,this.bars,bars,"bar");
42 * this.bars=bars;
43 * }
44 * </pre>
45 */
46 public class Container
47 {
48 private static final Logger LOG = Log.getLogger(Container.class);
49 private final CopyOnWriteArrayList<Container.Listener> _listeners=new CopyOnWriteArrayList<Container.Listener>();
50
51 public void addEventListener(Container.Listener listener)
52 {
53 _listeners.add(listener);
54 }
55
56 public void removeEventListener(Container.Listener listener)
57 {
58 _listeners.remove(listener);
59 }
60
61 /* ------------------------------------------------------------ */
62 /** Update single parent to child relationship.
63 * @param parent The parent of the child.
64 * @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.
65 * @param child The current child. If this is non null and differs from <code>oldChild</code>, then an add event is generated.
66 * @param relationship The name of the relationship
67 */
68 public void update(Object parent, Object oldChild, final Object child, String relationship)
69 {
70 if (oldChild!=null && !oldChild.equals(child))
71 remove(parent,oldChild,relationship);
72 if (child!=null && !child.equals(oldChild))
73 add(parent,child,relationship);
74 }
75
76 /* ------------------------------------------------------------ */
77 /** Update single parent to child relationship.
78 * @param parent The parent of the child.
79 * @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.
80 * @param child The current child. If this is non null and differs from <code>oldChild</code>, then an add event is generated.
81 * @param relationship The name of the relationship
82 * @param addRemove If true add/remove is called for the new/old children as well as the relationships
83 */
84 public void update(Object parent, Object oldChild, final Object child, String relationship,boolean addRemove)
85 {
86 if (oldChild!=null && !oldChild.equals(child))
87 {
88 remove(parent,oldChild,relationship);
89 if (addRemove)
90 removeBean(oldChild);
91 }
92
93 if (child!=null && !child.equals(oldChild))
94 {
95 if (addRemove)
96 addBean(child);
97 add(parent,child,relationship);
98 }
99 }
100
101 /* ------------------------------------------------------------ */
102 /** Update multiple parent to child relationship.
103 * @param parent The parent of the child.
104 * @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.
105 * This array is modified and children that remain in the new children array are nulled out of the old children array.
106 * @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.
107 * @param relationship The name of the relationship
108 */
109 public void update(Object parent, Object[] oldChildren, final Object[] children, String relationship)
110 {
111 update(parent,oldChildren,children,relationship,false);
112 }
113
114 /* ------------------------------------------------------------ */
115 /** Update multiple parent to child relationship.
116 * @param parent The parent of the child.
117 * @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.
118 * This array is modified and children that remain in the new children array are nulled out of the old children array.
119 * @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.
120 * @param relationship The name of the relationship
121 * @param addRemove If true add/remove is called for the new/old children as well as the relationships
122 */
123 public void update(Object parent, Object[] oldChildren, final Object[] children, String relationship, boolean addRemove)
124 {
125 Object[] newChildren = null;
126 if (children!=null)
127 {
128 newChildren = new Object[children.length];
129
130 for (int i=children.length;i-->0;)
131 {
132 boolean new_child=true;
133 if (oldChildren!=null)
134 {
135 for (int j=oldChildren.length;j-->0;)
136 {
137 if (children[i]!=null && children[i].equals(oldChildren[j]))
138 {
139 oldChildren[j]=null;
140 new_child=false;
141 }
142 }
143 }
144 if (new_child)
145 newChildren[i]=children[i];
146 }
147 }
148
149 if (oldChildren!=null)
150 {
151 for (int i=oldChildren.length;i-->0;)
152 {
153 if (oldChildren[i]!=null)
154 {
155 remove(parent,oldChildren[i],relationship);
156 if (addRemove)
157 removeBean(oldChildren[i]);
158 }
159 }
160 }
161
162 if (newChildren!=null)
163 {
164 for (int i=0;i<newChildren.length;i++)
165 if (newChildren[i]!=null)
166 {
167 if (addRemove)
168 addBean(newChildren[i]);
169 add(parent,newChildren[i],relationship);
170 }
171 }
172 }
173
174 /* ------------------------------------------------------------ */
175 public void addBean(Object obj)
176 {
177 if (_listeners!=null)
178 {
179 for (int i=0; i<LazyList.size(_listeners); i++)
180 {
181 Listener listener=(Listener)LazyList.get(_listeners, i);
182 listener.addBean(obj);
183 }
184 }
185 }
186
187 /* ------------------------------------------------------------ */
188 public void removeBean(Object obj)
189 {
190 if (_listeners!=null)
191 {
192 for (int i=0; i<LazyList.size(_listeners); i++)
193 ((Listener)LazyList.get(_listeners, i)).removeBean(obj);
194 }
195 }
196
197 /* ------------------------------------------------------------ */
198 /** Add a parent child relationship
199 * @param parent
200 * @param child
201 * @param relationship
202 */
203 private void add(Object parent, Object child, String relationship)
204 {
205 if (LOG.isDebugEnabled())
206 LOG.debug("Container "+parent+" + "+child+" as "+relationship);
207 if (_listeners!=null)
208 {
209 Relationship event=new Relationship(this,parent,child,relationship);
210 for (int i=0; i<LazyList.size(_listeners); i++)
211 ((Listener)LazyList.get(_listeners, i)).add(event);
212 }
213 }
214
215 /* ------------------------------------------------------------ */
216 /** remove a parent child relationship
217 * @param parent
218 * @param child
219 * @param relationship
220 */
221 private void remove(Object parent, Object child, String relationship)
222 {
223 if (LOG.isDebugEnabled())
224 LOG.debug("Container "+parent+" - "+child+" as "+relationship);
225 if (_listeners!=null)
226 {
227 Relationship event=new Relationship(this,parent,child,relationship);
228 for (int i=0; i<LazyList.size(_listeners); i++)
229 ((Listener)LazyList.get(_listeners, i)).remove(event);
230 }
231 }
232
233 /* ------------------------------------------------------------ */
234 /** A Container event.
235 * @see Listener
236 */
237 public static class Relationship
238 {
239 private final WeakReference<Object> _parent;
240 private final WeakReference<Object> _child;
241 private String _relationship;
242 private Container _container;
243
244 private Relationship(Container container, Object parent,Object child, String relationship)
245 {
246 _container=container;
247 _parent=new WeakReference<Object>(parent);
248 _child=new WeakReference<Object>(child);
249 _relationship=relationship;
250 }
251
252 public Container getContainer()
253 {
254 return _container;
255 }
256
257 public Object getChild()
258 {
259 return _child.get();
260 }
261
262 public Object getParent()
263 {
264 return _parent.get();
265 }
266
267 public String getRelationship()
268 {
269 return _relationship;
270 }
271
272 @Override
273 public String toString()
274 {
275 return _parent+"---"+_relationship+"-->"+_child;
276 }
277
278 @Override
279 public int hashCode()
280 {
281 return _parent.hashCode()+_child.hashCode()+_relationship.hashCode();
282 }
283
284 @Override
285 public boolean equals(Object o)
286 {
287 if (o==null || !(o instanceof Relationship))
288 return false;
289 Relationship r = (Relationship)o;
290 return r._parent.get()==_parent.get() && r._child.get()==_child.get() && r._relationship.equals(_relationship);
291 }
292 }
293
294 /* ------------------------------------------------------------ */
295 /** Listener.
296 * A listener for Container events.
297 */
298 public interface Listener extends EventListener
299 {
300 public void addBean(Object bean);
301 public void removeBean(Object bean);
302 public void add(Container.Relationship relationship);
303 public void remove(Container.Relationship relationship);
304 }
305 }