1 |
772 |
jeremybenn |
/* ServiceRegistry.java -- A simple registry for service providers.
|
2 |
|
|
Copyright (C) 2004, 2005 Free Software Foundation, Inc.
|
3 |
|
|
|
4 |
|
|
This file is part of GNU Classpath.
|
5 |
|
|
|
6 |
|
|
GNU Classpath is free software; you can redistribute it and/or modify
|
7 |
|
|
it under the terms of the GNU General Public License as published by
|
8 |
|
|
the Free Software Foundation; either version 2, or (at your option)
|
9 |
|
|
any later version.
|
10 |
|
|
|
11 |
|
|
GNU Classpath is distributed in the hope that it will be useful, but
|
12 |
|
|
WITHOUT ANY WARRANTY; without even the implied warranty of
|
13 |
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
14 |
|
|
General Public License for more details.
|
15 |
|
|
|
16 |
|
|
You should have received a copy of the GNU General Public License
|
17 |
|
|
along with GNU Classpath; see the file COPYING. If not, write to the
|
18 |
|
|
Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
|
19 |
|
|
02110-1301 USA.
|
20 |
|
|
|
21 |
|
|
Linking this library statically or dynamically with other modules is
|
22 |
|
|
making a combined work based on this library. Thus, the terms and
|
23 |
|
|
conditions of the GNU General Public License cover the whole
|
24 |
|
|
combination.
|
25 |
|
|
|
26 |
|
|
As a special exception, the copyright holders of this library give you
|
27 |
|
|
permission to link this library with independent modules to produce an
|
28 |
|
|
executable, regardless of the license terms of these independent
|
29 |
|
|
modules, and to copy and distribute the resulting executable under
|
30 |
|
|
terms of your choice, provided that you also meet, for each linked
|
31 |
|
|
independent module, the terms and conditions of the license of that
|
32 |
|
|
module. An independent module is a module which is not derived from
|
33 |
|
|
or based on this library. If you modify this library, you may extend
|
34 |
|
|
this exception to your version of the library, but you are not
|
35 |
|
|
obligated to do so. If you do not wish to do so, delete this
|
36 |
|
|
exception statement from your version. */
|
37 |
|
|
|
38 |
|
|
|
39 |
|
|
package javax.imageio.spi;
|
40 |
|
|
|
41 |
|
|
import gnu.classpath.ServiceFactory;
|
42 |
|
|
|
43 |
|
|
import java.util.ArrayList;
|
44 |
|
|
import java.util.Collection;
|
45 |
|
|
import java.util.Collections;
|
46 |
|
|
import java.util.Comparator;
|
47 |
|
|
import java.util.HashSet;
|
48 |
|
|
import java.util.IdentityHashMap;
|
49 |
|
|
import java.util.Iterator;
|
50 |
|
|
import java.util.LinkedList;
|
51 |
|
|
import java.util.Map;
|
52 |
|
|
import java.util.NoSuchElementException;
|
53 |
|
|
import java.util.Set;
|
54 |
|
|
|
55 |
|
|
/**
|
56 |
|
|
* A registry for service providers.
|
57 |
|
|
*
|
58 |
|
|
* @since 1.4
|
59 |
|
|
*
|
60 |
|
|
* @author Michael Koch (konqueror@gmx.de)
|
61 |
|
|
* @author Sascha Brawer (brawer@dandelis.ch)
|
62 |
|
|
*/
|
63 |
|
|
public class ServiceRegistry
|
64 |
|
|
{
|
65 |
|
|
// Package-private to avoid a trampoline.
|
66 |
|
|
/**
|
67 |
|
|
* The service categories of this registry.
|
68 |
|
|
*
|
69 |
|
|
* <p>Note that we expect that only very few categories will
|
70 |
|
|
* typically be used with a registry. The most common case will be
|
71 |
|
|
* one, it seems unlikely that any registry would contain more than
|
72 |
|
|
* five or six categories. Therefore, we intentionally avoid the
|
73 |
|
|
* overhead of a HashMap.
|
74 |
|
|
*
|
75 |
|
|
* @see #providers
|
76 |
|
|
*/
|
77 |
|
|
final Class[] categories;
|
78 |
|
|
|
79 |
|
|
|
80 |
|
|
/**
|
81 |
|
|
* The registered providers for each service category, indexed by
|
82 |
|
|
* the same index as the {@link #categories} array. If no provider
|
83 |
|
|
* is registered for a category, the array entry will be
|
84 |
|
|
* <code>null</code>.
|
85 |
|
|
*
|
86 |
|
|
* <p>Note that we expect that only very few providers will
|
87 |
|
|
* typically be registered for a category. The most common case will
|
88 |
|
|
* be one or two. Therefore, we intentionally avoid the overhead of
|
89 |
|
|
* a HashMap.
|
90 |
|
|
*/
|
91 |
|
|
private final LinkedList[] providers;
|
92 |
|
|
|
93 |
|
|
|
94 |
|
|
/**
|
95 |
|
|
* The ordring constaints for each service category, indexed by the
|
96 |
|
|
* same index as the {@link #categories} array. The constraints for
|
97 |
|
|
* a service category are stored as a <code>Map<Object,
|
98 |
|
|
* Set<Object>></code>, where the Map’s values are
|
99 |
|
|
* those providers that need to come after the key. If no
|
100 |
|
|
* constraints are imposed on the providers of a category, the array
|
101 |
|
|
* entry will be <code>null</code>. If no constraints have been set
|
102 |
|
|
* whatsoever, <code>constraints</code> will be <code>null</code>.
|
103 |
|
|
*
|
104 |
|
|
* <p>Note that we expect that only very few constraints will
|
105 |
|
|
* typically be imposed on a category. The most common case will
|
106 |
|
|
* be zero.
|
107 |
|
|
*/
|
108 |
|
|
private IdentityHashMap[] constraints;
|
109 |
|
|
|
110 |
|
|
|
111 |
|
|
/**
|
112 |
|
|
* Constructs a <code>ServiceRegistry</code> for the specified
|
113 |
|
|
* service categories.
|
114 |
|
|
*
|
115 |
|
|
* @param categories the categories to support
|
116 |
|
|
*
|
117 |
|
|
* @throws IllegalArgumentException if <code>categories</code> is
|
118 |
|
|
* <code>null</code>, or if its {@link Iterator#next()} method
|
119 |
|
|
* returns <code>null</code>.
|
120 |
|
|
*
|
121 |
|
|
* @throws ClassCastException if <code>categories</code> does not
|
122 |
|
|
* iterate over instances of {@link java.lang.Class}.
|
123 |
|
|
*/
|
124 |
|
|
public ServiceRegistry(Iterator<Class<?>> categories)
|
125 |
|
|
{
|
126 |
|
|
ArrayList cats = new ArrayList(/* expected size */ 10);
|
127 |
|
|
|
128 |
|
|
if (categories == null)
|
129 |
|
|
throw new IllegalArgumentException();
|
130 |
|
|
|
131 |
|
|
while (categories.hasNext())
|
132 |
|
|
{
|
133 |
|
|
Class cat = (Class) categories.next();
|
134 |
|
|
if (cat == null)
|
135 |
|
|
throw new IllegalArgumentException();
|
136 |
|
|
cats.add(cat);
|
137 |
|
|
}
|
138 |
|
|
|
139 |
|
|
int numCats = cats.size();
|
140 |
|
|
this.categories = (Class[]) cats.toArray(new Class[numCats]);
|
141 |
|
|
this.providers = new LinkedList[numCats];
|
142 |
|
|
}
|
143 |
|
|
|
144 |
|
|
|
145 |
|
|
/**
|
146 |
|
|
* Finds service providers that are implementing the specified
|
147 |
|
|
* Service Provider Interface.
|
148 |
|
|
*
|
149 |
|
|
* <p><b>On-demand loading:</b> Loading and initializing service
|
150 |
|
|
* providers is delayed as much as possible. The rationale is that
|
151 |
|
|
* typical clients will iterate through the set of installed service
|
152 |
|
|
* providers until one is found that matches some criteria (like
|
153 |
|
|
* supported formats, or quality of service). In such scenarios, it
|
154 |
|
|
* might make sense to install only the frequently needed service
|
155 |
|
|
* providers on the local machine. More exotic providers can be put
|
156 |
|
|
* onto a server; the server will only be contacted when no suitable
|
157 |
|
|
* service could be found locally.</p>
|
158 |
|
|
*
|
159 |
|
|
* <p><b>Security considerations:</b> Any loaded service providers
|
160 |
|
|
* are loaded through the specified ClassLoader, or the system
|
161 |
|
|
* ClassLoader if <code>classLoader</code> is
|
162 |
|
|
* <code>null</code>. When <code>lookupProviders</code> is called,
|
163 |
|
|
* the current {@link java.security.AccessControlContext} gets
|
164 |
|
|
* recorded. This captured security context will determine the
|
165 |
|
|
* permissions when services get loaded via the <code>next()</code>
|
166 |
|
|
* method of the returned <code>Iterator</code>.</p>
|
167 |
|
|
*
|
168 |
|
|
* @param spi the service provider interface which must be
|
169 |
|
|
* implemented by any loaded service providers.
|
170 |
|
|
*
|
171 |
|
|
* @param loader the class loader that will be used to load the
|
172 |
|
|
* service providers, or <code>null</code> for the system class
|
173 |
|
|
* loader. For using the context class loader, see {@link
|
174 |
|
|
* #lookupProviders(Class)}.
|
175 |
|
|
*
|
176 |
|
|
* @return an iterator over instances of <code>spi</code>.
|
177 |
|
|
*
|
178 |
|
|
* @throws IllegalArgumentException if <code>spi</code> is
|
179 |
|
|
* <code>null</code>.
|
180 |
|
|
*/
|
181 |
|
|
public static <T> Iterator<T> lookupProviders(Class<T> spi,
|
182 |
|
|
ClassLoader loader)
|
183 |
|
|
{
|
184 |
|
|
return ServiceFactory.lookupProviders(spi, loader);
|
185 |
|
|
}
|
186 |
|
|
|
187 |
|
|
|
188 |
|
|
/**
|
189 |
|
|
* Finds service providers that are implementing the specified
|
190 |
|
|
* Service Provider Interface, using the context class loader
|
191 |
|
|
* for loading providers.
|
192 |
|
|
*
|
193 |
|
|
* @param spi the service provider interface which must be
|
194 |
|
|
* implemented by any loaded service providers.
|
195 |
|
|
*
|
196 |
|
|
* @return an iterator over instances of <code>spi</code>.
|
197 |
|
|
*
|
198 |
|
|
* @throws IllegalArgumentException if <code>spi</code> is
|
199 |
|
|
* <code>null</code>.
|
200 |
|
|
*
|
201 |
|
|
* @see #lookupProviders(Class, ClassLoader)
|
202 |
|
|
*/
|
203 |
|
|
public static <T> Iterator<T> lookupProviders(Class<T> spi)
|
204 |
|
|
{
|
205 |
|
|
return ServiceFactory.lookupProviders(spi);
|
206 |
|
|
}
|
207 |
|
|
|
208 |
|
|
|
209 |
|
|
/**
|
210 |
|
|
* Returns an iterator over all service categories.
|
211 |
|
|
*
|
212 |
|
|
* @return an unmodifiable {@link
|
213 |
|
|
* java.util.Iterator}<{@link java.lang.Class}>.
|
214 |
|
|
*/
|
215 |
|
|
public Iterator<Class<?>> getCategories()
|
216 |
|
|
{
|
217 |
|
|
return new Iterator()
|
218 |
|
|
{
|
219 |
|
|
int index = -1;
|
220 |
|
|
|
221 |
|
|
public boolean hasNext()
|
222 |
|
|
{
|
223 |
|
|
return index < categories.length - 1;
|
224 |
|
|
}
|
225 |
|
|
|
226 |
|
|
public Object next()
|
227 |
|
|
{
|
228 |
|
|
if (!hasNext())
|
229 |
|
|
throw new NoSuchElementException();
|
230 |
|
|
|
231 |
|
|
return categories[++index];
|
232 |
|
|
}
|
233 |
|
|
|
234 |
|
|
public void remove()
|
235 |
|
|
{
|
236 |
|
|
throw new UnsupportedOperationException();
|
237 |
|
|
}
|
238 |
|
|
};
|
239 |
|
|
}
|
240 |
|
|
|
241 |
|
|
|
242 |
|
|
/**
|
243 |
|
|
* Registers a provider for a service category which is specified by
|
244 |
|
|
* the class-internal category ID.
|
245 |
|
|
*
|
246 |
|
|
* @param provider the service provider to be registered.
|
247 |
|
|
*
|
248 |
|
|
* @param cat the service category, which is identified by an index
|
249 |
|
|
* into the {@link #categories} array.
|
250 |
|
|
*
|
251 |
|
|
* @return <code>true</code> if <code>provider</code> is the first
|
252 |
|
|
* provider that gets registered for the specified service category;
|
253 |
|
|
* <code>false</code> if other providers have already been
|
254 |
|
|
* registered for the same servide category.
|
255 |
|
|
*
|
256 |
|
|
* @throws IllegalArgumentException if <code>provider</code> is
|
257 |
|
|
* <code>null</code>.
|
258 |
|
|
*
|
259 |
|
|
* @throws ClassCastException if <code>provider</code> does not
|
260 |
|
|
* implement the specified service provider interface.
|
261 |
|
|
*/
|
262 |
|
|
private synchronized boolean registerServiceProvider(Object provider,
|
263 |
|
|
int cat)
|
264 |
|
|
{
|
265 |
|
|
LinkedList provs;
|
266 |
|
|
boolean result;
|
267 |
|
|
Class category;
|
268 |
|
|
|
269 |
|
|
if (provider == null)
|
270 |
|
|
throw new IllegalArgumentException();
|
271 |
|
|
|
272 |
|
|
category = categories[cat];
|
273 |
|
|
if (!category.isInstance(provider))
|
274 |
|
|
throw new ClassCastException(category.getName());
|
275 |
|
|
|
276 |
|
|
provs = providers[cat];
|
277 |
|
|
if (provs == null)
|
278 |
|
|
{
|
279 |
|
|
result = true;
|
280 |
|
|
provs = providers[cat] = new LinkedList();
|
281 |
|
|
}
|
282 |
|
|
else
|
283 |
|
|
result = false;
|
284 |
|
|
|
285 |
|
|
provs.add(provider);
|
286 |
|
|
if (provider instanceof RegisterableService)
|
287 |
|
|
((RegisterableService) provider).onRegistration(this, category);
|
288 |
|
|
|
289 |
|
|
return result;
|
290 |
|
|
}
|
291 |
|
|
|
292 |
|
|
|
293 |
|
|
/**
|
294 |
|
|
* Registers a provider for the specified service category.
|
295 |
|
|
*
|
296 |
|
|
* <p>If <code>provider</code> implements the {@link
|
297 |
|
|
* RegisterableService} interface, its {@link
|
298 |
|
|
* RegisterableService#onRegistration onRegistration} method is
|
299 |
|
|
* invoked in order to inform the provider about the addition to
|
300 |
|
|
* this registry.
|
301 |
|
|
*
|
302 |
|
|
* @param provider the service provider to be registered.
|
303 |
|
|
*
|
304 |
|
|
* @param category the service category under which
|
305 |
|
|
* <code>provider</code> shall be registered.
|
306 |
|
|
*
|
307 |
|
|
* @return <code>true</code> if <code>provider</code> is the first
|
308 |
|
|
* provider that gets registered for the specified service category;
|
309 |
|
|
* <code>false</code> if other providers have already been
|
310 |
|
|
* registered for the same servide category.
|
311 |
|
|
*
|
312 |
|
|
* @throws IllegalArgumentException if <code>provider</code> is
|
313 |
|
|
* <code>null</code>, or if <code>category</code> is not among the
|
314 |
|
|
* categories passed to the {@linkplain #ServiceRegistry(Iterator)
|
315 |
|
|
* constructor} of this ServiceRegistry.
|
316 |
|
|
*
|
317 |
|
|
* @throws ClassCastException if <code>provider</code> does not
|
318 |
|
|
* implement <code>category</code>.
|
319 |
|
|
*/
|
320 |
|
|
public synchronized <T> boolean registerServiceProvider(T provider,
|
321 |
|
|
Class<T> category)
|
322 |
|
|
{
|
323 |
|
|
for (int i = 0; i < categories.length; i++)
|
324 |
|
|
if (categories[i] == category)
|
325 |
|
|
return registerServiceProvider(provider, i);
|
326 |
|
|
throw new IllegalArgumentException();
|
327 |
|
|
}
|
328 |
|
|
|
329 |
|
|
|
330 |
|
|
/**
|
331 |
|
|
* Registers a provider under all service categories it
|
332 |
|
|
* implements.
|
333 |
|
|
*
|
334 |
|
|
* <p>If <code>provider</code> implements the {@link
|
335 |
|
|
* RegisterableService} interface, its {@link
|
336 |
|
|
* RegisterableService#onRegistration onRegistration} method is
|
337 |
|
|
* invoked in order to inform the provider about the addition to
|
338 |
|
|
* this registry. If <code>provider</code> implements several
|
339 |
|
|
* service categories, <code>onRegistration</code> gets called
|
340 |
|
|
* multiple times.
|
341 |
|
|
*
|
342 |
|
|
* @param provider the service provider to be registered.
|
343 |
|
|
*
|
344 |
|
|
* @throws IllegalArgumentException if <code>provider</code> is
|
345 |
|
|
* <code>null</code>, or if <code>provider</code> does not implement
|
346 |
|
|
* any of the service categories passed to the {@linkplain
|
347 |
|
|
* #ServiceRegistry(Iterator) constructor} of this ServiceRegistry.
|
348 |
|
|
*/
|
349 |
|
|
public synchronized void registerServiceProvider(Object provider)
|
350 |
|
|
{
|
351 |
|
|
boolean ok = false;
|
352 |
|
|
|
353 |
|
|
if (provider == null)
|
354 |
|
|
throw new IllegalArgumentException();
|
355 |
|
|
|
356 |
|
|
for (int i = 0; i < categories.length; i++)
|
357 |
|
|
if (categories[i].isInstance(provider))
|
358 |
|
|
{
|
359 |
|
|
ok = true;
|
360 |
|
|
registerServiceProvider(provider, i);
|
361 |
|
|
}
|
362 |
|
|
|
363 |
|
|
if (!ok)
|
364 |
|
|
throw new IllegalArgumentException();
|
365 |
|
|
}
|
366 |
|
|
|
367 |
|
|
|
368 |
|
|
/**
|
369 |
|
|
* Registers a number of providers under all service categories they
|
370 |
|
|
* implement.
|
371 |
|
|
*
|
372 |
|
|
* <p>If a provider implements the {@link RegisterableService}
|
373 |
|
|
* interface, its {@link RegisterableService#onRegistration
|
374 |
|
|
* onRegistration} method is invoked in order to inform the provider
|
375 |
|
|
* about the addition to this registry. If <code>provider</code>
|
376 |
|
|
* implements several service categories,
|
377 |
|
|
* <code>onRegistration</code> gets called multiple times.
|
378 |
|
|
*
|
379 |
|
|
* @throws IllegalArgumentException if <code>providers</code> is
|
380 |
|
|
* <code>null</code>, if any iterated provider is <code>null</code>,
|
381 |
|
|
* or if some iterated provider does not implement any of the
|
382 |
|
|
* service categories passed to the {@linkplain
|
383 |
|
|
* #ServiceRegistry(Iterator) constructor} of this
|
384 |
|
|
* <code>ServiceRegistry</code>.
|
385 |
|
|
*/
|
386 |
|
|
public synchronized void registerServiceProviders(Iterator<?> providers)
|
387 |
|
|
{
|
388 |
|
|
if (providers == null)
|
389 |
|
|
throw new IllegalArgumentException();
|
390 |
|
|
|
391 |
|
|
while (providers.hasNext())
|
392 |
|
|
registerServiceProvider(providers.next());
|
393 |
|
|
}
|
394 |
|
|
|
395 |
|
|
|
396 |
|
|
/**
|
397 |
|
|
* De-registers a provider for a service category which is specified
|
398 |
|
|
* by the class-internal category ID.
|
399 |
|
|
*
|
400 |
|
|
* @param provider the service provider to be registered.
|
401 |
|
|
*
|
402 |
|
|
* @param cat the service category, which is identified by an index
|
403 |
|
|
* into the {@link #categories} array.
|
404 |
|
|
*
|
405 |
|
|
* @return <code>true</code> if <code>provider</code> was previously
|
406 |
|
|
* registered for the specified service category; <code>false</code>
|
407 |
|
|
* if if the provider had not been registered.
|
408 |
|
|
*
|
409 |
|
|
* @throws IllegalArgumentException if <code>provider</code> is
|
410 |
|
|
* <code>null</code>.
|
411 |
|
|
*
|
412 |
|
|
* @throws ClassCastException if <code>provider</code> does not
|
413 |
|
|
* implement the specified service provider interface.
|
414 |
|
|
*/
|
415 |
|
|
private synchronized boolean deregisterServiceProvider(Object provider,
|
416 |
|
|
int cat)
|
417 |
|
|
{
|
418 |
|
|
LinkedList provs;
|
419 |
|
|
boolean result;
|
420 |
|
|
Class category;
|
421 |
|
|
|
422 |
|
|
if (provider == null)
|
423 |
|
|
throw new IllegalArgumentException();
|
424 |
|
|
|
425 |
|
|
category = categories[cat];
|
426 |
|
|
if (!category.isInstance(provider))
|
427 |
|
|
throw new ClassCastException(category.getName());
|
428 |
|
|
|
429 |
|
|
provs = providers[cat];
|
430 |
|
|
if (provs == null)
|
431 |
|
|
return false;
|
432 |
|
|
|
433 |
|
|
result = provs.remove(provider);
|
434 |
|
|
if (provs.isEmpty())
|
435 |
|
|
providers[cat] = null;
|
436 |
|
|
|
437 |
|
|
if (result && (provider instanceof RegisterableService))
|
438 |
|
|
((RegisterableService) provider).onDeregistration(this, category);
|
439 |
|
|
|
440 |
|
|
return result;
|
441 |
|
|
}
|
442 |
|
|
|
443 |
|
|
|
444 |
|
|
/**
|
445 |
|
|
* De-registers a provider for the specified service category.
|
446 |
|
|
*
|
447 |
|
|
* <p>If <code>provider</code> implements the {@link
|
448 |
|
|
* RegisterableService} interface, its {@link
|
449 |
|
|
* RegisterableService#onDeregistration onDeregistration} method is
|
450 |
|
|
* invoked in order to inform the provider about the removal from
|
451 |
|
|
* this registry.
|
452 |
|
|
*
|
453 |
|
|
* @param provider the service provider to be de-registered.
|
454 |
|
|
*
|
455 |
|
|
* @param category the service category from which
|
456 |
|
|
* <code>provider</code> shall be de-registered.
|
457 |
|
|
*
|
458 |
|
|
* @return <code>true</code> if <code>provider</code> was previously
|
459 |
|
|
* registered for the specified service category; <code>false</code>
|
460 |
|
|
* if if the provider had not been registered.
|
461 |
|
|
*
|
462 |
|
|
* @throws IllegalArgumentException if <code>provider</code> is
|
463 |
|
|
* <code>null</code>, or if <code>category</code> is not among the
|
464 |
|
|
* categories passed to the {@linkplain #ServiceRegistry(Iterator)
|
465 |
|
|
* constructor} of this ServiceRegistry.
|
466 |
|
|
*
|
467 |
|
|
* @throws ClassCastException if <code>provider</code> does not
|
468 |
|
|
* implement <code>category</code>.
|
469 |
|
|
*/
|
470 |
|
|
public synchronized <T> boolean deregisterServiceProvider(T provider,
|
471 |
|
|
Class<T> category)
|
472 |
|
|
{
|
473 |
|
|
for (int i = 0; i < categories.length; i++)
|
474 |
|
|
if (categories[i] == category)
|
475 |
|
|
return deregisterServiceProvider(provider, i);
|
476 |
|
|
throw new IllegalArgumentException();
|
477 |
|
|
}
|
478 |
|
|
|
479 |
|
|
|
480 |
|
|
/**
|
481 |
|
|
* De-registers a provider from all service categories it
|
482 |
|
|
* implements.
|
483 |
|
|
*
|
484 |
|
|
* <p>If <code>provider</code> implements the {@link
|
485 |
|
|
* RegisterableService} interface, its {@link
|
486 |
|
|
* RegisterableService#onDeregistration onDeregistration} method is
|
487 |
|
|
* invoked in order to inform the provider about the removal from
|
488 |
|
|
* this registry. If <code>provider</code> implements several
|
489 |
|
|
* service categories, <code>onDeregistration</code> gets called
|
490 |
|
|
* multiple times.</p>
|
491 |
|
|
*
|
492 |
|
|
* @param provider the service provider to be de-registered.
|
493 |
|
|
*
|
494 |
|
|
* @throws IllegalArgumentException if <code>provider</code> is
|
495 |
|
|
* <code>null</code>, or if <code>provider</code> does not implement
|
496 |
|
|
* any of the service categories passed to the {@linkplain
|
497 |
|
|
* #ServiceRegistry(Iterator) constructor} of this
|
498 |
|
|
* <code>ServiceRegistry</code>.
|
499 |
|
|
*/
|
500 |
|
|
public synchronized void deregisterServiceProvider(Object provider)
|
501 |
|
|
{
|
502 |
|
|
boolean ok = false;
|
503 |
|
|
|
504 |
|
|
if (provider == null)
|
505 |
|
|
throw new IllegalArgumentException();
|
506 |
|
|
|
507 |
|
|
for (int i = 0; i < categories.length; i++)
|
508 |
|
|
if (categories[i].isInstance(provider))
|
509 |
|
|
{
|
510 |
|
|
ok = true;
|
511 |
|
|
deregisterServiceProvider(provider, i);
|
512 |
|
|
}
|
513 |
|
|
|
514 |
|
|
if (!ok)
|
515 |
|
|
throw new IllegalArgumentException();
|
516 |
|
|
}
|
517 |
|
|
|
518 |
|
|
|
519 |
|
|
/**
|
520 |
|
|
* De-registers all providers which have been registered for the
|
521 |
|
|
* specified service category.
|
522 |
|
|
*
|
523 |
|
|
* <p>If a provider implements the {@link RegisterableService}
|
524 |
|
|
* interface, its {@link RegisterableService#onDeregistration
|
525 |
|
|
* onDeregistration} method is invoked in order to inform the
|
526 |
|
|
* provider about the removal from this registry. If the provider
|
527 |
|
|
* implements several service categories,
|
528 |
|
|
* <code>onDeregistration</code> gets called multiple times.
|
529 |
|
|
*
|
530 |
|
|
* @param category the category whose registered providers will be
|
531 |
|
|
* de-registered.
|
532 |
|
|
*
|
533 |
|
|
* @throws IllegalArgumentException if <code>category</code> is not
|
534 |
|
|
* among the categories passed to the {@linkplain
|
535 |
|
|
* #ServiceRegistry(Iterator) constructor} of this
|
536 |
|
|
* <code>ServiceRegistry</code>.
|
537 |
|
|
*/
|
538 |
|
|
public synchronized void deregisterAll(Class<?> category)
|
539 |
|
|
{
|
540 |
|
|
boolean ok = false;
|
541 |
|
|
|
542 |
|
|
for (int i = 0; i < categories.length; i++)
|
543 |
|
|
{
|
544 |
|
|
if (categories[i] != category)
|
545 |
|
|
continue;
|
546 |
|
|
|
547 |
|
|
ok = true;
|
548 |
|
|
while (providers[i] != null)
|
549 |
|
|
deregisterServiceProvider(providers[i].get(0), i);
|
550 |
|
|
}
|
551 |
|
|
|
552 |
|
|
if (!ok)
|
553 |
|
|
throw new IllegalArgumentException();
|
554 |
|
|
}
|
555 |
|
|
|
556 |
|
|
|
557 |
|
|
/**
|
558 |
|
|
* De-registers all service providers.
|
559 |
|
|
*
|
560 |
|
|
* <p>If a provider implements the {@link RegisterableService}
|
561 |
|
|
* interface, its {@link RegisterableService#onDeregistration
|
562 |
|
|
* onDeregistration} method is invoked in order to inform the
|
563 |
|
|
* provider about the removal from this registry. If the provider
|
564 |
|
|
* implements several service categories,
|
565 |
|
|
* <code>onDeregistration</code> gets called multiple times.
|
566 |
|
|
*/
|
567 |
|
|
public synchronized void deregisterAll()
|
568 |
|
|
{
|
569 |
|
|
for (int i = 0; i < categories.length; i++)
|
570 |
|
|
while (providers[i] != null)
|
571 |
|
|
deregisterServiceProvider(providers[i].get(0), i);
|
572 |
|
|
}
|
573 |
|
|
|
574 |
|
|
|
575 |
|
|
/**
|
576 |
|
|
* Called by the Virtual Machine when it detects that this
|
577 |
|
|
* <code>ServiceRegistry</code> has become garbage. De-registers all
|
578 |
|
|
* service providers, which will cause those that implement {@link
|
579 |
|
|
* RegisterableService} to receive a {@link
|
580 |
|
|
* RegisterableService#onDeregistration onDeregistration}
|
581 |
|
|
* notification.
|
582 |
|
|
*/
|
583 |
|
|
public void finalize()
|
584 |
|
|
throws Throwable
|
585 |
|
|
{
|
586 |
|
|
super.finalize();
|
587 |
|
|
deregisterAll();
|
588 |
|
|
}
|
589 |
|
|
|
590 |
|
|
|
591 |
|
|
/**
|
592 |
|
|
* Determines whether a provider has been registered with this
|
593 |
|
|
* registry.
|
594 |
|
|
*
|
595 |
|
|
* @return <code>true</code> if <code>provider</code> has been
|
596 |
|
|
* registered under any service category; <code>false</code> if
|
597 |
|
|
* it is not registered.
|
598 |
|
|
*
|
599 |
|
|
* @throws IllegalArgumentException if <code>provider</code> is
|
600 |
|
|
* <code>null</code>.
|
601 |
|
|
*/
|
602 |
|
|
public synchronized boolean contains(Object provider)
|
603 |
|
|
{
|
604 |
|
|
if (provider == null)
|
605 |
|
|
throw new IllegalArgumentException();
|
606 |
|
|
|
607 |
|
|
// Note that contains is rather unlikely to be ever called,
|
608 |
|
|
// so it would be wasteful to keep a special data structure
|
609 |
|
|
// (such as a HashSet) for making it a fast operation.
|
610 |
|
|
for (int i = 0; i < providers.length; i++)
|
611 |
|
|
{
|
612 |
|
|
// If provider does not implement categories[i],
|
613 |
|
|
// it would not have been possible to register it there.
|
614 |
|
|
// In that case, it would be pointless to look there.
|
615 |
|
|
if (!categories[i].isInstance(provider))
|
616 |
|
|
continue;
|
617 |
|
|
|
618 |
|
|
// But if the list of registered providers contains provider,
|
619 |
|
|
// we have found it.
|
620 |
|
|
LinkedList p = providers[i];
|
621 |
|
|
if (p != null && p.contains(provider))
|
622 |
|
|
return true;
|
623 |
|
|
}
|
624 |
|
|
|
625 |
|
|
return false;
|
626 |
|
|
}
|
627 |
|
|
|
628 |
|
|
|
629 |
|
|
/**
|
630 |
|
|
* Returns the index in {@link #categories} occupied by the
|
631 |
|
|
* specified service category.
|
632 |
|
|
*
|
633 |
|
|
* @throws IllegalArgumentException if <code>category</code> is not
|
634 |
|
|
* among the categories passed to the {@linkplain
|
635 |
|
|
* #ServiceRegistry(Iterator) constructor} of this ServiceRegistry.
|
636 |
|
|
*/
|
637 |
|
|
private int getCategoryID(Class category)
|
638 |
|
|
{
|
639 |
|
|
for (int i = 0; i < categories.length; i++)
|
640 |
|
|
if (categories[i] == category)
|
641 |
|
|
return i;
|
642 |
|
|
|
643 |
|
|
throw new IllegalArgumentException();
|
644 |
|
|
}
|
645 |
|
|
|
646 |
|
|
|
647 |
|
|
/**
|
648 |
|
|
* Retrieves all providers that have been registered for the
|
649 |
|
|
* specified service category.
|
650 |
|
|
*
|
651 |
|
|
* @param category the service category whose providers are
|
652 |
|
|
* to be retrieved.
|
653 |
|
|
*
|
654 |
|
|
* @param useOrdering <code>true</code> in order to retrieve the
|
655 |
|
|
* providers in an order imposed by the {@linkplain #setOrdering
|
656 |
|
|
* ordering constraints}; <code>false</code> in order to retrieve
|
657 |
|
|
* the providers in any order.
|
658 |
|
|
*
|
659 |
|
|
* @throws IllegalArgumentException if <code>category</code> is not
|
660 |
|
|
* among the categories passed to the {@linkplain
|
661 |
|
|
* #ServiceRegistry(Iterator) constructor} of this
|
662 |
|
|
* <code>ServiceRegistry</code>.
|
663 |
|
|
*
|
664 |
|
|
* @see #getServiceProviders(Class, Filter, boolean)
|
665 |
|
|
*/
|
666 |
|
|
public <T> Iterator<T> getServiceProviders(Class<T> category,
|
667 |
|
|
boolean useOrdering)
|
668 |
|
|
{
|
669 |
|
|
return getServiceProviders(category, null, useOrdering);
|
670 |
|
|
}
|
671 |
|
|
|
672 |
|
|
|
673 |
|
|
/**
|
674 |
|
|
* Retrieves all providers that have been registered for the
|
675 |
|
|
* specified service category and that satisfy the criteria
|
676 |
|
|
* of a custom filter.
|
677 |
|
|
*
|
678 |
|
|
* @param category the service category whose providers are
|
679 |
|
|
* to be retrieved.
|
680 |
|
|
*
|
681 |
|
|
* @param filter a custom filter, or <code>null</code> to
|
682 |
|
|
* retrieve all registered providers for the specified
|
683 |
|
|
* category.
|
684 |
|
|
*
|
685 |
|
|
* @param useOrdering <code>true</code> in order to retrieve the
|
686 |
|
|
* providers in an order imposed by the {@linkplain #setOrdering
|
687 |
|
|
* ordering constraints}; <code>false</code> in order to retrieve
|
688 |
|
|
* the providers in any order.
|
689 |
|
|
*
|
690 |
|
|
* @throws IllegalArgumentException if <code>category</code> is not
|
691 |
|
|
* among the categories passed to the {@linkplain
|
692 |
|
|
* #ServiceRegistry(Iterator) constructor} of this
|
693 |
|
|
* <code>ServiceRegistry</code>.
|
694 |
|
|
*/
|
695 |
|
|
public synchronized <T> Iterator<T> getServiceProviders(Class<T> category,
|
696 |
|
|
Filter filter,
|
697 |
|
|
boolean useOrdering)
|
698 |
|
|
{
|
699 |
|
|
int catid;
|
700 |
|
|
LinkedList provs;
|
701 |
|
|
ArrayList result;
|
702 |
|
|
|
703 |
|
|
catid = getCategoryID(category);
|
704 |
|
|
provs = providers[catid];
|
705 |
|
|
if (provs == null)
|
706 |
|
|
return Collections.EMPTY_LIST.iterator();
|
707 |
|
|
|
708 |
|
|
result = new ArrayList(provs.size());
|
709 |
|
|
for (Iterator iter = provs.iterator(); iter.hasNext();)
|
710 |
|
|
{
|
711 |
|
|
Object provider = iter.next();
|
712 |
|
|
if (filter == null || filter.filter(provider))
|
713 |
|
|
result.add(provider);
|
714 |
|
|
}
|
715 |
|
|
|
716 |
|
|
// If we are supposed to obey ordering constraints, and
|
717 |
|
|
// if any constraints have been imposed on the specified
|
718 |
|
|
// service category, sort the result.
|
719 |
|
|
if (useOrdering && constraints != null)
|
720 |
|
|
{
|
721 |
|
|
final Map cons = constraints[catid];
|
722 |
|
|
if (cons != null)
|
723 |
|
|
Collections.sort(result, new Comparator()
|
724 |
|
|
{
|
725 |
|
|
public int compare(Object o1, Object o2)
|
726 |
|
|
{
|
727 |
|
|
Set s;
|
728 |
|
|
|
729 |
|
|
if (o1 == o2)
|
730 |
|
|
return 0;
|
731 |
|
|
|
732 |
|
|
s = (Set) cons.get(o1);
|
733 |
|
|
if (s != null && s.contains(o2))
|
734 |
|
|
return -1; // o1 < o2
|
735 |
|
|
|
736 |
|
|
s = (Set) cons.get(o2);
|
737 |
|
|
if (s != null && s.contains(o1))
|
738 |
|
|
return 1; // o1 > o2
|
739 |
|
|
|
740 |
|
|
return 0; // o1 == o2
|
741 |
|
|
}
|
742 |
|
|
});
|
743 |
|
|
}
|
744 |
|
|
|
745 |
|
|
return result.iterator();
|
746 |
|
|
}
|
747 |
|
|
|
748 |
|
|
|
749 |
|
|
/**
|
750 |
|
|
* Returns one of the service providers that is a subclass of the
|
751 |
|
|
* specified class.
|
752 |
|
|
*
|
753 |
|
|
* @param providerClass a class to search for.
|
754 |
|
|
*/
|
755 |
|
|
public synchronized <T> T getServiceProviderByClass(Class<T> providerClass)
|
756 |
|
|
{
|
757 |
|
|
if (providerClass == null)
|
758 |
|
|
throw new IllegalArgumentException();
|
759 |
|
|
|
760 |
|
|
// Note that the method getServiceProviderByClass is rather
|
761 |
|
|
// unlikely to be ever called, so it would be wasteful to keep a
|
762 |
|
|
// special data structure for making it a fast operation.
|
763 |
|
|
for (int cat = 0; cat < categories.length; cat++)
|
764 |
|
|
{
|
765 |
|
|
if (!categories[cat].isAssignableFrom(providerClass))
|
766 |
|
|
continue;
|
767 |
|
|
|
768 |
|
|
LinkedList provs = providers[cat];
|
769 |
|
|
if (provs == null)
|
770 |
|
|
continue;
|
771 |
|
|
|
772 |
|
|
for (Iterator iter = provs.iterator(); iter.hasNext();)
|
773 |
|
|
{
|
774 |
|
|
Object provider = iter.next();
|
775 |
|
|
if (providerClass.isInstance(provider))
|
776 |
|
|
return (T) provider;
|
777 |
|
|
}
|
778 |
|
|
}
|
779 |
|
|
|
780 |
|
|
return null;
|
781 |
|
|
}
|
782 |
|
|
|
783 |
|
|
|
784 |
|
|
/**
|
785 |
|
|
* Adds an ordering constraint on service providers.
|
786 |
|
|
*
|
787 |
|
|
* @param category the service category to which an ordering
|
788 |
|
|
* constraint is to be added.
|
789 |
|
|
*
|
790 |
|
|
* @param firstProvider the provider which is supposed to come before
|
791 |
|
|
* <code>second</code>.
|
792 |
|
|
*
|
793 |
|
|
* @param secondProvider the provider which is supposed to come after
|
794 |
|
|
* <code>first</code>.
|
795 |
|
|
*
|
796 |
|
|
* @throws IllegalArgumentException if <code>first</code> and
|
797 |
|
|
* <code>second</code> are referring to the same object, or if one
|
798 |
|
|
* of them is <code>null</code>.
|
799 |
|
|
*
|
800 |
|
|
* @see #unsetOrdering
|
801 |
|
|
* @see #getServiceProviders(Class, Filter, boolean)
|
802 |
|
|
*/
|
803 |
|
|
public synchronized <T> boolean setOrdering(Class<T> category,
|
804 |
|
|
T firstProvider,
|
805 |
|
|
T secondProvider)
|
806 |
|
|
{
|
807 |
|
|
return addConstraint(getCategoryID(category), firstProvider,
|
808 |
|
|
secondProvider);
|
809 |
|
|
}
|
810 |
|
|
|
811 |
|
|
|
812 |
|
|
/**
|
813 |
|
|
* Removes an ordering constraint on service providers.
|
814 |
|
|
*
|
815 |
|
|
* @param category the service category from which an ordering
|
816 |
|
|
* constraint is to be removed.
|
817 |
|
|
*
|
818 |
|
|
* @param firstProvider the provider which is supposed to come before
|
819 |
|
|
* <code>second</code>.
|
820 |
|
|
*
|
821 |
|
|
* @param secondProvider the provider which is supposed to come after
|
822 |
|
|
* <code>first</code>.
|
823 |
|
|
*
|
824 |
|
|
* @throws IllegalArgumentException if <code>first</code> and
|
825 |
|
|
* <code>second</code> are referring to the same object, or if one
|
826 |
|
|
* of them is <code>null</code>.
|
827 |
|
|
*
|
828 |
|
|
* @see #setOrdering
|
829 |
|
|
*/
|
830 |
|
|
public synchronized <T> boolean unsetOrdering(Class<T> category,
|
831 |
|
|
T firstProvider,
|
832 |
|
|
T secondProvider)
|
833 |
|
|
{
|
834 |
|
|
return removeConstraint(getCategoryID(category),
|
835 |
|
|
firstProvider, secondProvider);
|
836 |
|
|
}
|
837 |
|
|
|
838 |
|
|
|
839 |
|
|
/**
|
840 |
|
|
* Adds an ordering constraint on service providers.
|
841 |
|
|
*
|
842 |
|
|
* @param catid the service category ID, which is the
|
843 |
|
|
* category’s index into the {@link #categories} array.
|
844 |
|
|
*
|
845 |
|
|
* @param first the provider which is supposed to come before
|
846 |
|
|
* <code>second</code>.
|
847 |
|
|
*
|
848 |
|
|
* @param second the provider which is supposed to come after
|
849 |
|
|
* <code>first</code>.
|
850 |
|
|
*
|
851 |
|
|
* @throws IllegalArgumentException if <code>first</code> and
|
852 |
|
|
* <code>second</code> are referring to the same object, or if one
|
853 |
|
|
* of them is <code>null</code>.
|
854 |
|
|
*/
|
855 |
|
|
private boolean addConstraint(int catid, Object first, Object second)
|
856 |
|
|
{
|
857 |
|
|
Set s;
|
858 |
|
|
IdentityHashMap cons;
|
859 |
|
|
|
860 |
|
|
// Also checks argument validity.
|
861 |
|
|
removeConstraint(catid, second, first);
|
862 |
|
|
|
863 |
|
|
if (constraints == null)
|
864 |
|
|
constraints = new IdentityHashMap[categories.length];
|
865 |
|
|
cons = constraints[catid];
|
866 |
|
|
if (cons == null)
|
867 |
|
|
cons = constraints[catid] = new IdentityHashMap();
|
868 |
|
|
|
869 |
|
|
s = (Set) cons.get(first);
|
870 |
|
|
if (s == null)
|
871 |
|
|
cons.put(first, s = new HashSet());
|
872 |
|
|
return s.add(second);
|
873 |
|
|
}
|
874 |
|
|
|
875 |
|
|
|
876 |
|
|
/**
|
877 |
|
|
* Removes an ordering constraint on service providers.
|
878 |
|
|
*
|
879 |
|
|
* @param catid the service category ID, which is the
|
880 |
|
|
* category’s index into the {@link #categories} array.
|
881 |
|
|
*
|
882 |
|
|
* @param first the provider which is supposed to come before
|
883 |
|
|
* <code>second</code>.
|
884 |
|
|
*
|
885 |
|
|
* @param second the provider which is supposed to come after
|
886 |
|
|
* <code>first</code>.
|
887 |
|
|
*
|
888 |
|
|
* @throws IllegalArgumentException if <code>first</code> and
|
889 |
|
|
* <code>second</code> are referring to the same object, or if one
|
890 |
|
|
* of them is <code>null</code>.
|
891 |
|
|
*/
|
892 |
|
|
private boolean removeConstraint(int catid, Object first, Object second)
|
893 |
|
|
{
|
894 |
|
|
Collection s;
|
895 |
|
|
IdentityHashMap cons;
|
896 |
|
|
|
897 |
|
|
if (first == null || second == null || first == second)
|
898 |
|
|
throw new IllegalArgumentException();
|
899 |
|
|
|
900 |
|
|
if (constraints == null)
|
901 |
|
|
return false;
|
902 |
|
|
|
903 |
|
|
cons = constraints[catid];
|
904 |
|
|
if (cons == null)
|
905 |
|
|
return false;
|
906 |
|
|
|
907 |
|
|
s = (Collection) cons.get(first);
|
908 |
|
|
if (s == null)
|
909 |
|
|
return false;
|
910 |
|
|
|
911 |
|
|
if (!s.remove(second))
|
912 |
|
|
return false;
|
913 |
|
|
|
914 |
|
|
// If we removed the last constraint for a service category,
|
915 |
|
|
// we can get free some memory.
|
916 |
|
|
if (cons.isEmpty())
|
917 |
|
|
{
|
918 |
|
|
constraints[catid] = null;
|
919 |
|
|
boolean anyConstraints = false;
|
920 |
|
|
for (int i = 0; i < constraints.length; i++)
|
921 |
|
|
{
|
922 |
|
|
if (constraints[i] != null)
|
923 |
|
|
{
|
924 |
|
|
anyConstraints = true;
|
925 |
|
|
break;
|
926 |
|
|
}
|
927 |
|
|
}
|
928 |
|
|
if (!anyConstraints)
|
929 |
|
|
constraints = null;
|
930 |
|
|
}
|
931 |
|
|
|
932 |
|
|
return true;
|
933 |
|
|
}
|
934 |
|
|
|
935 |
|
|
|
936 |
|
|
/**
|
937 |
|
|
* A filter for selecting service providers that match custom
|
938 |
|
|
* criteria.
|
939 |
|
|
*
|
940 |
|
|
* @see ServiceRegistry#getServiceProviders(Class, Filter,
|
941 |
|
|
* boolean)
|
942 |
|
|
*
|
943 |
|
|
* @since 1.4
|
944 |
|
|
*
|
945 |
|
|
* @author Michael Koch (konqueror@gmx.de)
|
946 |
|
|
* @author Sascha Brawer (brawer@dandelis.ch)
|
947 |
|
|
*/
|
948 |
|
|
public static interface Filter
|
949 |
|
|
{
|
950 |
|
|
/**
|
951 |
|
|
* Checks whether the specified service provider matches the
|
952 |
|
|
* constraints of this Filter.
|
953 |
|
|
*
|
954 |
|
|
* @param provider the service provider in question.
|
955 |
|
|
*
|
956 |
|
|
* @return <code>true</code> if <code>provider</code> matches the
|
957 |
|
|
* criteria; <code>false</code> if it does not match.
|
958 |
|
|
*/
|
959 |
|
|
boolean filter(Object provider);
|
960 |
|
|
}
|
961 |
|
|
}
|