Frames | No Frames |
1: /* ======================================================================== 2: * JCommon : a free general purpose class library for the Java(tm) platform 3: * ======================================================================== 4: * 5: * (C) Copyright 2000-2005, by Object Refinery Limited and Contributors. 6: * 7: * Project Info: http://www.jfree.org/jcommon/index.html 8: * 9: * This library is free software; you can redistribute it and/or modify it 10: * under the terms of the GNU Lesser General Public License as published by 11: * the Free Software Foundation; either version 2.1 of the License, or 12: * (at your option) any later version. 13: * 14: * This library is distributed in the hope that it will be useful, but 15: * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 16: * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public 17: * License for more details. 18: * 19: * You should have received a copy of the GNU Lesser General Public 20: * License along with this library; if not, write to the Free Software 21: * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, 22: * USA. 23: * 24: * [Java is a trademark or registered trademark of Sun Microsystems, Inc. 25: * in the United States and other countries.] 26: * 27: * --------------------- 28: * ObjectUtilitiess.java 29: * --------------------- 30: * (C) Copyright 2003-2005, by Object Refinery Limited. 31: * 32: * Original Author: David Gilbert (for Object Refinery Limited); 33: * Contributor(s): -; 34: * 35: * $Id: ObjectUtilities.java,v 1.21 2008/09/10 09:24:41 mungady Exp $ 36: * 37: * Changes 38: * ------- 39: * 25-Mar-2003 : Version 1 (DG); 40: * 15-Sep-2003 : Fixed bug in clone(List) method (DG); 41: * 25-Nov-2004 : Modified clone(Object) method to fail with objects that 42: * cannot be cloned, added new deepClone(Collection) method. 43: * Renamed ObjectUtils --> ObjectUtilities (DG); 44: * 11-Jan-2005 : Removed deprecated code in preparation for 1.0.0 release (DG); 45: * 18-Aug-2005 : Added casts to suppress compiler warnings, as suggested in 46: * patch 1260622 (DG); 47: * 48: */ 49: 50: package org.jfree.util; 51: 52: import java.io.IOException; 53: import java.io.InputStream; 54: import java.lang.reflect.InvocationTargetException; 55: import java.lang.reflect.Method; 56: import java.lang.reflect.Modifier; 57: import java.net.URL; 58: import java.util.ArrayList; 59: import java.util.Collection; 60: import java.util.Iterator; 61: import java.util.StringTokenizer; 62: 63: /** 64: * A collection of useful static utility methods for handling classes and object 65: * instantiation. 66: * 67: * @author Thomas Morgner 68: */ 69: public final class ObjectUtilities { 70: 71: /** 72: * A constant for using the TheadContext as source for the classloader. 73: */ 74: public static final String THREAD_CONTEXT = "ThreadContext"; 75: /** 76: * A constant for using the ClassContext as source for the classloader. 77: */ 78: public static final String CLASS_CONTEXT = "ClassContext"; 79: 80: /** 81: * By default use the thread context. 82: */ 83: private static String classLoaderSource = THREAD_CONTEXT; 84: /** 85: * The custom classloader to be used (if not null). 86: */ 87: private static ClassLoader classLoader; 88: 89: /** 90: * Default constructor - private. 91: */ 92: private ObjectUtilities() { 93: } 94: 95: /** 96: * Returns the internal configuration entry, whether the classloader of 97: * the thread context or the context classloader should be used. 98: * 99: * @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 static synchronized 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 static ClassLoader getClassLoader(final Class c) { 258: final String localClassLoaderSource; 259: synchronized(ObjectUtilities.class) 260: { 261: if (classLoader != null) { 262: return classLoader; 263: } 264: localClassLoaderSource = classLoaderSource; 265: } 266: 267: if ("ThreadContext".equals(localClassLoaderSource)) { 268: final ClassLoader threadLoader = Thread.currentThread().getContextClassLoader(); 269: if (threadLoader != null) { 270: return threadLoader; 271: } 272: } 273: 274: // Context classloader - do not cache .. 275: final ClassLoader applicationCL = c.getClassLoader(); 276: if (applicationCL == null) { 277: return ClassLoader.getSystemClassLoader(); 278: } 279: else { 280: return applicationCL; 281: } 282: } 283: 284: 285: /** 286: * Returns the resource specified by the <strong>absolute</strong> name. 287: * 288: * @param name the name of the resource 289: * @param c the source class 290: * @return the url of the resource or null, if not found. 291: */ 292: public static URL getResource(final String name, final Class c) { 293: final ClassLoader cl = getClassLoader(c); 294: if (cl == null) { 295: return null; 296: } 297: return cl.getResource(name); 298: } 299: 300: /** 301: * Returns the resource specified by the <strong>relative</strong> name. 302: * 303: * @param name the name of the resource relative to the given class 304: * @param c the source class 305: * @return the url of the resource or null, if not found. 306: */ 307: public static URL getResourceRelative(final String name, final Class c) { 308: final ClassLoader cl = getClassLoader(c); 309: final String cname = convertName(name, c); 310: if (cl == null) { 311: return null; 312: } 313: return cl.getResource(cname); 314: } 315: 316: /** 317: * Transform the class-relative resource name into a global name by 318: * appending it to the classes package name. If the name is already a 319: * global name (the name starts with a "/"), then the name is returned 320: * unchanged. 321: * 322: * @param name the resource name 323: * @param c the class which the resource is relative to 324: * @return the tranformed name. 325: */ 326: private static String convertName(final String name, Class c) { 327: if (name.startsWith("/")) { 328: // strip leading slash.. 329: return name.substring(1); 330: } 331: 332: // we cant work on arrays, so remove them ... 333: while (c.isArray()) { 334: c = c.getComponentType(); 335: } 336: // extract the package ... 337: final String baseName = c.getName(); 338: final int index = baseName.lastIndexOf('.'); 339: if (index == -1) { 340: return name; 341: } 342: 343: final String pkgName = baseName.substring(0, index); 344: return pkgName.replace('.', '/') + "/" + name; 345: } 346: 347: /** 348: * Returns the inputstream for the resource specified by the 349: * <strong>absolute</strong> name. 350: * 351: * @param name the name of the resource 352: * @param context the source class 353: * @return the url of the resource or null, if not found. 354: */ 355: public static InputStream getResourceAsStream(final String name, 356: final Class context) { 357: final URL url = getResource(name, context); 358: if (url == null) { 359: return null; 360: } 361: 362: try { 363: return url.openStream(); 364: } 365: catch (IOException e) { 366: return null; 367: } 368: } 369: 370: /** 371: * Returns the inputstream for the resource specified by the 372: * <strong>relative</strong> name. 373: * 374: * @param name the name of the resource relative to the given class 375: * @param context the source class 376: * @return the url of the resource or null, if not found. 377: */ 378: public static InputStream getResourceRelativeAsStream 379: (final String name, final Class context) { 380: final URL url = getResourceRelative(name, context); 381: if (url == null) { 382: return null; 383: } 384: 385: try { 386: return url.openStream(); 387: } 388: catch (IOException e) { 389: return null; 390: } 391: } 392: 393: /** 394: * Tries to create a new instance of the given class. This is a short cut 395: * for the common bean instantiation code. 396: * 397: * @param className the class name as String, never null. 398: * @param source the source class, from where to get the classloader. 399: * @return the instantiated object or null, if an error occured. 400: */ 401: public static Object loadAndInstantiate(final String className, 402: final Class source) { 403: try { 404: final ClassLoader loader = getClassLoader(source); 405: final Class c = loader.loadClass(className); 406: return c.newInstance(); 407: } 408: catch (Exception e) { 409: return null; 410: } 411: } 412: 413: /** 414: * Tries to create a new instance of the given class. This is a short cut 415: * for the common bean instantiation code. This method is a type-safe method 416: * and will not instantiate the class unless it is an instance of the given 417: * type. 418: * 419: * @param className the class name as String, never null. 420: * @param source the source class, from where to get the classloader. 421: * @param type the type. 422: * @return the instantiated object or null, if an error occurred. 423: */ 424: public static Object loadAndInstantiate(final String className, 425: final Class source, 426: final Class type) { 427: try { 428: final ClassLoader loader = getClassLoader(source); 429: final Class c = loader.loadClass(className); 430: if (type.isAssignableFrom(c)) { 431: return c.newInstance(); 432: } 433: } 434: catch (Exception e) { 435: return null; 436: } 437: return null; 438: } 439: 440: /** 441: * Returns <code>true</code> if this is version 1.4 or later of the 442: * Java runtime. 443: * 444: * @return A boolean. 445: */ 446: public static boolean isJDK14() { 447: try { 448: final ClassLoader loader = getClassLoader(ObjectUtilities.class); 449: if (loader != null) { 450: try { 451: loader.loadClass("java.util.RandomAccess"); 452: return true; 453: } 454: catch (ClassNotFoundException e) { 455: return false; 456: } 457: catch(Exception e) { 458: // do nothing, but do not crash ... 459: } 460: } 461: } 462: catch (Exception e) { 463: // cant do anything about it, we have to accept and ignore it .. 464: } 465: 466: // OK, the quick and dirty, but secure way failed. Lets try it 467: // using the standard way. 468: try { 469: final String version = System.getProperty 470: ("java.vm.specification.version"); 471: // parse the beast... 472: if (version == null) { 473: return false; 474: } 475: 476: String[] versions = parseVersions(version); 477: String[] target = new String[]{ "1", "4" }; 478: return (ArrayUtilities.compareVersionArrays(versions, target) >= 0); 479: } 480: catch(Exception e) { 481: return false; 482: } 483: } 484: 485: private static String[] parseVersions (String version) 486: { 487: if (version == null) 488: { 489: return new String[0]; 490: } 491: 492: final ArrayList versions = new ArrayList(); 493: final StringTokenizer strtok = new StringTokenizer(version, "."); 494: while (strtok.hasMoreTokens()) 495: { 496: versions.add (strtok.nextToken()); 497: } 498: return (String[]) versions.toArray(new String[versions.size()]); 499: } 500: }