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 }