001 /* ========================================================================
002 * JCommon : a free general purpose class library for the Java(tm) platform
003 * ========================================================================
004 *
005 * (C) Copyright 2000-2005, by Object Refinery Limited and Contributors.
006 *
007 * Project Info: http://www.jfree.org/jcommon/index.html
008 *
009 * This library is free software; you can redistribute it and/or modify it
010 * under the terms of the GNU Lesser General Public License as published by
011 * the Free Software Foundation; either version 2.1 of the License, or
012 * (at your option) any later version.
013 *
014 * This library is distributed in the hope that it will be useful, but
015 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
016 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
017 * License for more details.
018 *
019 * You should have received a copy of the GNU Lesser General Public
020 * License along with this library; if not, write to the Free Software
021 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
022 * USA.
023 *
024 * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
025 * in the United States and other countries.]
026 *
027 * ---------------------
028 * ObjectUtilitiess.java
029 * ---------------------
030 * (C) Copyright 2003-2005, by Object Refinery Limited.
031 *
032 * Original Author: David Gilbert (for Object Refinery Limited);
033 * Contributor(s): -;
034 *
035 * $Id: ObjectUtilities.java,v 1.17 2006/12/03 15:33:33 taqua Exp $
036 *
037 * Changes
038 * -------
039 * 25-Mar-2003 : Version 1 (DG);
040 * 15-Sep-2003 : Fixed bug in clone(List) method (DG);
041 * 25-Nov-2004 : Modified clone(Object) method to fail with objects that
042 * cannot be cloned, added new deepClone(Collection) method.
043 * Renamed ObjectUtils --> ObjectUtilities (DG);
044 * 11-Jan-2005 : Removed deprecated code in preparation for 1.0.0 release (DG);
045 * 18-Aug-2005 : Added casts to suppress compiler warnings, as suggested in
046 * patch 1260622 (DG);
047 *
048 */
049
050 package org.jfree.util;
051
052 import java.io.IOException;
053 import java.io.InputStream;
054 import java.lang.reflect.InvocationTargetException;
055 import java.lang.reflect.Method;
056 import java.lang.reflect.Modifier;
057 import java.net.URL;
058 import java.util.Collection;
059 import java.util.Iterator;
060 import java.util.ArrayList;
061 import java.util.StringTokenizer;
062
063 /**
064 * A collection of useful static utility methods for handling classes and object
065 * instantiation.
066 *
067 * @author Thomas Morgner
068 */
069 public final class ObjectUtilities {
070
071 /**
072 * A constant for using the TheadContext as source for the classloader.
073 */
074 public static final String THREAD_CONTEXT = "ThreadContext";
075 /**
076 * A constant for using the ClassContext as source for the classloader.
077 */
078 public static final String CLASS_CONTEXT = "ClassContext";
079
080 /**
081 * By default use the thread context.
082 */
083 private static String classLoaderSource = THREAD_CONTEXT;
084 /**
085 * The custom classloader to be used (if not null).
086 */
087 private static ClassLoader classLoader;
088
089 /**
090 * Default constructor - private.
091 */
092 private ObjectUtilities() {
093 }
094
095 /**
096 * Returns the internal configuration entry, whether the classloader of
097 * the thread context or the context classloader should be used.
098 *
099 * @return the classloader source, either THREAD_CONTEXT or CLASS_CONTEXT.
100 */
101 public static String getClassLoaderSource() {
102 return classLoaderSource;
103 }
104
105 /**
106 * Defines the internal configuration entry, whether the classloader of
107 * the thread context or the context classloader should be used.
108 * <p/>
109 * This setting can only be defined using the API, there is no safe way
110 * to put this into an external configuration file.
111 *
112 * @param classLoaderSource the classloader source,
113 * either THREAD_CONTEXT or CLASS_CONTEXT.
114 */
115 public static void setClassLoaderSource(final String classLoaderSource) {
116 ObjectUtilities.classLoaderSource = classLoaderSource;
117 }
118
119 /**
120 * Returns <code>true</code> if the two objects are equal OR both
121 * <code>null</code>.
122 *
123 * @param o1 object 1 (<code>null</code> permitted).
124 * @param o2 object 2 (<code>null</code> permitted).
125 * @return <code>true</code> or <code>false</code>.
126 */
127 public static boolean equal(final Object o1, final Object o2) {
128 if (o1 == o2) {
129 return true;
130 }
131 if (o1 != null) {
132 return o1.equals(o2);
133 }
134 else {
135 return false;
136 }
137 }
138
139 /**
140 * Returns a hash code for an object, or zero if the object is
141 * <code>null</code>.
142 *
143 * @param object the object (<code>null</code> permitted).
144 * @return The object's hash code (or zero if the object is
145 * <code>null</code>).
146 */
147 public static int hashCode(final Object object) {
148 int result = 0;
149 if (object != null) {
150 result = object.hashCode();
151 }
152 return result;
153 }
154
155 /**
156 * Returns a clone of the specified object, if it can be cloned, otherwise
157 * throws a CloneNotSupportedException.
158 *
159 * @param object the object to clone (<code>null</code> not permitted).
160 * @return A clone of the specified object.
161 * @throws CloneNotSupportedException if the object cannot be cloned.
162 */
163 public static Object clone(final Object object)
164 throws CloneNotSupportedException {
165 if (object == null) {
166 throw new IllegalArgumentException("Null 'object' argument.");
167 }
168 if (object instanceof PublicCloneable) {
169 final PublicCloneable pc = (PublicCloneable) object;
170 return pc.clone();
171 }
172 else {
173 try {
174 final Method method = object.getClass().getMethod("clone",
175 (Class[]) null);
176 if (Modifier.isPublic(method.getModifiers())) {
177 return method.invoke(object, (Object[]) null);
178 }
179 }
180 catch (NoSuchMethodException e) {
181 Log.warn("Object without clone() method is impossible.");
182 }
183 catch (IllegalAccessException e) {
184 Log.warn("Object.clone(): unable to call method.");
185 }
186 catch (InvocationTargetException e) {
187 Log.warn("Object without clone() method is impossible.");
188 }
189 }
190 throw new CloneNotSupportedException("Failed to clone.");
191 }
192
193 /**
194 * Returns a new collection containing clones of all the items in the
195 * specified collection.
196 *
197 * @param collection the collection (<code>null</code> not permitted).
198 * @return A new collection containing clones of all the items in the
199 * specified collection.
200 * @throws CloneNotSupportedException if any of the items in the collection
201 * cannot be cloned.
202 */
203 public static Collection deepClone(final Collection collection)
204 throws CloneNotSupportedException {
205
206 if (collection == null) {
207 throw new IllegalArgumentException("Null 'collection' argument.");
208 }
209 // all JDK-Collections are cloneable ...
210 // and if the collection is not clonable, then we should throw
211 // a CloneNotSupportedException anyway ...
212 final Collection result
213 = (Collection) ObjectUtilities.clone(collection);
214 result.clear();
215 final Iterator iterator = collection.iterator();
216 while (iterator.hasNext()) {
217 final Object item = iterator.next();
218 if (item != null) {
219 result.add(clone(item));
220 }
221 else {
222 result.add(null);
223 }
224 }
225 return result;
226 }
227
228 /**
229 * Redefines the custom classloader.
230 *
231 * @param classLoader the new classloader or null to use the default.
232 */
233 public synchronized static void setClassLoader(
234 final ClassLoader classLoader) {
235 ObjectUtilities.classLoader = classLoader;
236 }
237
238 /**
239 * Returns the custom classloader or null, if no custom classloader is defined.
240 *
241 * @return the custom classloader or null to use the default.
242 */
243 public static ClassLoader getClassLoader() {
244 return classLoader;
245 }
246
247 /**
248 * Returns the classloader, which was responsible for loading the given
249 * class.
250 *
251 * @param c the classloader, either an application class loader or the
252 * boot loader.
253 * @return the classloader, never null.
254 * @throws SecurityException if the SecurityManager does not allow to grab
255 * the context classloader.
256 */
257 public synchronized static ClassLoader getClassLoader(final Class c) {
258 if (classLoader != null) {
259 return classLoader;
260 }
261 if ("ThreadContext".equals(classLoaderSource)) {
262 final ClassLoader threadLoader
263 = Thread.currentThread().getContextClassLoader();
264 if (threadLoader != null) {
265 return threadLoader;
266 }
267 }
268
269 // Context classloader - do not cache ..
270 final ClassLoader applicationCL = c.getClassLoader();
271 if (applicationCL == null) {
272 return ClassLoader.getSystemClassLoader();
273 }
274 else {
275 return applicationCL;
276 }
277 }
278
279
280 /**
281 * Returns the resource specified by the <strong>absolute</strong> name.
282 *
283 * @param name the name of the resource
284 * @param c the source class
285 * @return the url of the resource or null, if not found.
286 */
287 public static URL getResource(final String name, final Class c) {
288 final ClassLoader cl = getClassLoader(c);
289 if (cl == null) {
290 return null;
291 }
292 return cl.getResource(name);
293 }
294
295 /**
296 * Returns the resource specified by the <strong>relative</strong> name.
297 *
298 * @param name the name of the resource relative to the given class
299 * @param c the source class
300 * @return the url of the resource or null, if not found.
301 */
302 public static URL getResourceRelative(final String name, final Class c) {
303 final ClassLoader cl = getClassLoader(c);
304 final String cname = convertName(name, c);
305 if (cl == null) {
306 return null;
307 }
308 return cl.getResource(cname);
309 }
310
311 /**
312 * Transform the class-relative resource name into a global name by
313 * appending it to the classes package name. If the name is already a
314 * global name (the name starts with a "/"), then the name is returned
315 * unchanged.
316 *
317 * @param name the resource name
318 * @param c the class which the resource is relative to
319 * @return the tranformed name.
320 */
321 private static String convertName(final String name, Class c) {
322 if (name.startsWith("/")) {
323 // strip leading slash..
324 return name.substring(1);
325 }
326
327 // we cant work on arrays, so remove them ...
328 while (c.isArray()) {
329 c = c.getComponentType();
330 }
331 // extract the package ...
332 final String baseName = c.getName();
333 final int index = baseName.lastIndexOf('.');
334 if (index == -1) {
335 return name;
336 }
337
338 final String pkgName = baseName.substring(0, index);
339 return pkgName.replace('.', '/') + "/" + name;
340 }
341
342 /**
343 * Returns the inputstream for the resource specified by the
344 * <strong>absolute</strong> name.
345 *
346 * @param name the name of the resource
347 * @param context the source class
348 * @return the url of the resource or null, if not found.
349 */
350 public static InputStream getResourceAsStream(final String name,
351 final Class context) {
352 final URL url = getResource(name, context);
353 if (url == null) {
354 return null;
355 }
356
357 try {
358 return url.openStream();
359 }
360 catch (IOException e) {
361 return null;
362 }
363 }
364
365 /**
366 * Returns the inputstream for the resource specified by the
367 * <strong>relative</strong> name.
368 *
369 * @param name the name of the resource relative to the given class
370 * @param context the source class
371 * @return the url of the resource or null, if not found.
372 */
373 public static InputStream getResourceRelativeAsStream
374 (final String name, final Class context) {
375 final URL url = getResourceRelative(name, context);
376 if (url == null) {
377 return null;
378 }
379
380 try {
381 return url.openStream();
382 }
383 catch (IOException e) {
384 return null;
385 }
386 }
387
388 /**
389 * Tries to create a new instance of the given class. This is a short cut
390 * for the common bean instantiation code.
391 *
392 * @param className the class name as String, never null.
393 * @param source the source class, from where to get the classloader.
394 * @return the instantiated object or null, if an error occured.
395 */
396 public static Object loadAndInstantiate(final String className,
397 final Class source) {
398 try {
399 final ClassLoader loader = getClassLoader(source);
400 final Class c = loader.loadClass(className);
401 return c.newInstance();
402 }
403 catch (Exception e) {
404 return null;
405 }
406 }
407
408 /**
409 * Tries to create a new instance of the given class. This is a short cut
410 * for the common bean instantiation code. This method is a type-safe method
411 * and will not instantiate the class unless it is an instance of the given
412 * type.
413 *
414 * @param className the class name as String, never null.
415 * @param source the source class, from where to get the classloader.
416 * @return the instantiated object or null, if an error occured.
417 */
418 public static Object loadAndInstantiate(final String className,
419 final Class source,
420 final Class type) {
421 try {
422 final ClassLoader loader = getClassLoader(source);
423 final Class c = loader.loadClass(className);
424 if (type.isAssignableFrom(c)) {
425 return c.newInstance();
426 }
427 }
428 catch (Exception e) {
429 return null;
430 }
431 return null;
432 }
433
434
435 public static boolean isJDK14() {
436 final ClassLoader loader = getClassLoader(ObjectUtilities.class);
437 if (loader != null) {
438 try {
439 loader.loadClass("java.util.RandomAccess");
440 return true;
441 }
442 catch (ClassNotFoundException e) {
443 return false;
444 }
445 catch(Exception e) {
446 // do nothing, but do not crash ...
447 }
448 }
449 // OK, the quick and dirty, but secure way failed. Lets try it
450 // using the standard way.
451 try {
452 final String version = System.getProperty
453 ("java.vm.specification.version");
454 // parse the beast...
455 if (version == null) {
456 return false;
457 }
458
459 String[] versions = parseVersions(version);
460 String[] target = new String[]{ "1", "4" };
461 return (ArrayUtilities.compareVersionArrays(versions, target) >= 0);
462 }
463 catch(Exception e) {
464 return false;
465 }
466 }
467
468 private static String[] parseVersions (String version)
469 {
470 if (version == null)
471 {
472 return new String[0];
473 }
474
475 final ArrayList versions = new ArrayList();
476 StringTokenizer strtok = new StringTokenizer(version, ".");
477 while (strtok.hasMoreTokens())
478 {
479 versions.add (strtok.nextToken());
480 }
481 return (String[]) versions.toArray(new String[versions.size()]);
482 }
483 }