content: /* ========================================================================
   * JCommon : a free general purpose class library for the Java(tm) platform
   * ========================================================================
   *
   * (C) Copyright 2000-2005, by Object Refinery Limited and Contributors.
   *
   * Project Info:  http://www.jfree.org/jcommon/index.html
   *
   * This library is free software; you can redistribute it and/or modify it
   * under the terms of the GNU Lesser General Public License as published by
   * the Free Software Foundation; either version 2.1 of the License, or
   * (at your option) any later version.
   *
   * This library is distributed in the hope that it will be useful, but
   * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
   * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
   * License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with this library; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
   * USA.
   *
   * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
   * in the United States and other countries.]
   *
   * ---------------------
   * ObjectUtilitiess.java
   * ---------------------
   * (C) Copyright 2003-2005, by Object Refinery Limited.
   *
   * Original Author:  David Gilbert (for Object Refinery Limited);
   * Contributor(s):   -;
   *
   * $Id: ObjectUtilities.java,v 1.21 2008/09/10 09:24:41 mungady Exp $
   *
   * Changes
   * -------
   * 25-Mar-2003 : Version 1 (DG);
   * 15-Sep-2003 : Fixed bug in clone(List) method (DG);
   * 25-Nov-2004 : Modified clone(Object) method to fail with objects that
   *               cannot be cloned, added new deepClone(Collection) method.
   *               Renamed ObjectUtils --> ObjectUtilities (DG);
   * 11-Jan-2005 : Removed deprecated code in preparation for 1.0.0 release (DG);
   * 18-Aug-2005 : Added casts to suppress compiler warnings, as suggested in
   *               patch 1260622 (DG);
   *
   */
  
  package org.jfree.util;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.lang.reflect.InvocationTargetException;
  import java.lang.reflect.Method;
  import java.lang.reflect.Modifier;
  import java.net.URL;
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.Iterator;
  import java.util.StringTokenizer;
  
  /**
   * A collection of useful static utility methods for handling classes and object
   * instantiation.
   *
   * @author Thomas Morgner
   */
  public final class ObjectUtilities {
  
      /**
       * A constant for using the TheadContext as source for the classloader.
       */
      public static final String THREAD_CONTEXT = "ThreadContext";
      /**
       * A constant for using the ClassContext as source for the classloader.
       */
      public static final String CLASS_CONTEXT = "ClassContext";
  
      /**
       * By default use the thread context.
       */
      private static String classLoaderSource = THREAD_CONTEXT;
      /**
       * The custom classloader to be used (if not null).
       */
      private static ClassLoader classLoader;
  
      /**
       * Default constructor - private.
       */
      private ObjectUtilities() {
      }
  
      /**
       * Returns the internal configuration entry, whether the classloader of
       * the thread context or the context classloader should be used.
       *
       * @return the classloader source, either THREAD_CONTEXT or CLASS_CONTEXT.
       */
      public static String getClassLoaderSource() {
          return classLoaderSource;
      }
  
      /**
       * Defines the internal configuration entry, whether the classloader of
       * the thread context or the context classloader should be used.
       * <p/>
       * This setting can only be defined using the API, there is no safe way
       * to put this into an external configuration file.
       *
       * @param classLoaderSource the classloader source,
       *                          either THREAD_CONTEXT or CLASS_CONTEXT.
       */
      public static void setClassLoaderSource(final String classLoaderSource) {
          ObjectUtilities.classLoaderSource = classLoaderSource;
      }
  
      /**
       * Returns <code>true</code> if the two objects are equal OR both
       * <code>null</code>.
       *
       * @param o1 object 1 (<code>null</code> permitted).
       * @param o2 object 2 (<code>null</code> permitted).
       * @return <code>true</code> or <code>false</code>.
       */
      public static boolean equal(final Object o1, final Object o2) {
          if (o1 == o2) {
              return true;
          }
          if (o1 != null) {
              return o1.equals(o2);
          }
          else {
              return false;
          }
      }
  
      /**
       * Returns a hash code for an object, or zero if the object is
       * <code>null</code>.
       *
       * @param object the object (<code>null</code> permitted).
       * @return The object's hash code (or zero if the object is
       *         <code>null</code>).
       */
      public static int hashCode(final Object object) {
          int result = 0;
          if (object != null) {
              result = object.hashCode();
          }
          return result;
      }
  
      /**
       * Returns a clone of the specified object, if it can be cloned, otherwise
       * throws a CloneNotSupportedException.
       *
       * @param object the object to clone (<code>null</code> not permitted).
       * @return A clone of the specified object.
       * @throws CloneNotSupportedException if the object cannot be cloned.
       */
      public static Object clone(final Object object)
          throws CloneNotSupportedException {
          if (object == null) {
              throw new IllegalArgumentException("Null 'object' argument.");
          }
          if (object instanceof PublicCloneable) {
              final PublicCloneable pc = (PublicCloneable) object;
              return pc.clone();
          }
          else {
              try {
                  final Method method = object.getClass().getMethod("clone",
                          (Class[]) null);
                  if (Modifier.isPublic(method.getModifiers())) {
                      return method.invoke(object, (Object[]) null);
                  }
              }
              catch (NoSuchMethodException e) {
                  Log.warn("Object without clone() method is impossible.");
              }
              catch (IllegalAccessException e) {
                  Log.warn("Object.clone(): unable to call method.");
              }
              catch (InvocationTargetException e) {
                  Log.warn("Object without clone() method is impossible.");
              }
          }
          throw new CloneNotSupportedException("Failed to clone.");
      }
  
      /**
       * Returns a new collection containing clones of all the items in the
       * specified collection.
       *
       * @param collection the collection (<code>null</code> not permitted).
       * @return A new collection containing clones of all the items in the
       *         specified collection.
       * @throws CloneNotSupportedException if any of the items in the collection
       *                                    cannot be cloned.
       */
      public static Collection deepClone(final Collection collection)
          throws CloneNotSupportedException {
  
          if (collection == null) {
              throw new IllegalArgumentException("Null 'collection' argument.");
          }
          // all JDK-Collections are cloneable ...
          // and if the collection is not clonable, then we should throw
          // a CloneNotSupportedException anyway ...
          final Collection result
              = (Collection) ObjectUtilities.clone(collection);
          result.clear();
          final Iterator iterator = collection.iterator();
          while (iterator.hasNext()) {
              final Object item = iterator.next();
              if (item != null) {
                  result.add(clone(item));
              }
              else {
                  result.add(null);
              }
          }
          return result;
      }
  
      /**
       * Redefines the custom classloader.
       *
       * @param classLoader the new classloader or null to use the default.
       */
      public static synchronized void setClassLoader(
              final ClassLoader classLoader) {
          ObjectUtilities.classLoader = classLoader;
      }
  
      /**
       * Returns the custom classloader or null, if no custom classloader is defined.
       *
       * @return the custom classloader or null to use the default.
       */
      public static ClassLoader getClassLoader() {
        return classLoader;
      }
  
      /**
       * Returns the classloader, which was responsible for loading the given
       * class.
       *
       * @param c the classloader, either an application class loader or the
       *          boot loader.
       * @return the classloader, never null.
       * @throws SecurityException if the SecurityManager does not allow to grab
       *                           the context classloader.
       */
      public static ClassLoader getClassLoader(final Class c) {
          final String localClassLoaderSource;
          synchronized(ObjectUtilities.class)
          {
            if (classLoader != null) {
                return classLoader;
            }
            localClassLoaderSource = classLoaderSource;
          }
  
          if ("ThreadContext".equals(localClassLoaderSource)) {
              final ClassLoader threadLoader = Thread.currentThread().getContextClassLoader();
              if (threadLoader != null) {
                  return threadLoader;
              }
          }
  
          // Context classloader - do not cache ..
          final ClassLoader applicationCL = c.getClassLoader();
          if (applicationCL == null) {
              return ClassLoader.getSystemClassLoader();
          }
          else {
              return applicationCL;
          }
      }
  
  
      /**
       * Returns the resource specified by the <strong>absolute</strong> name.
       *
       * @param name the name of the resource
       * @param c    the source class
       * @return the url of the resource or null, if not found.
       */
      public static URL getResource(final String name, final Class c) {
          final ClassLoader cl = getClassLoader(c);
          if (cl == null) {
              return null;
          }
          return cl.getResource(name);
      }
  
      /**
       * Returns the resource specified by the <strong>relative</strong> name.
       *
       * @param name the name of the resource relative to the given class
       * @param c    the source class
       * @return the url of the resource or null, if not found.
       */
      public static URL getResourceRelative(final String name, final Class c) {
          final ClassLoader cl = getClassLoader(c);
          final String cname = convertName(name, c);
          if (cl == null) {
              return null;
          }
          return cl.getResource(cname);
      }
  
      /**
       * Transform the class-relative resource name into a global name by
       * appending it to the classes package name. If the name is already a
       * global name (the name starts with a "/"), then the name is returned
       * unchanged.
       *
       * @param name the resource name
       * @param c    the class which the resource is relative to
       * @return the tranformed name.
       */
      private static String convertName(final String name, Class c) {
          if (name.startsWith("/")) {
              // strip leading slash..
              return name.substring(1);
          }
  
          // we cant work on arrays, so remove them ...
          while (c.isArray()) {
              c = c.getComponentType();
          }
          // extract the package ...
          final String baseName = c.getName();
          final int index = baseName.lastIndexOf('.');
          if (index == -1) {
              return name;
          }
  
          final String pkgName = baseName.substring(0, index);
          return pkgName.replace('.', '/') + "/" + name;
      }
  
      /**
       * Returns the inputstream for the resource specified by the
       * <strong>absolute</strong> name.
       *
       * @param name the name of the resource
       * @param context the source class
       * @return the url of the resource or null, if not found.
       */
      public static InputStream getResourceAsStream(final String name,
                                                    final Class context) {
          final URL url = getResource(name, context);
          if (url == null) {
              return null;
          }
  
          try {
              return url.openStream();
          }
          catch (IOException e) {
              return null;
          }
      }
  
      /**
       * Returns the inputstream for the resource specified by the
       * <strong>relative</strong> name.
       *
       * @param name the name of the resource relative to the given class
       * @param context the source class
       * @return the url of the resource or null, if not found.
       */
      public static InputStream getResourceRelativeAsStream
          (final String name, final Class context) {
          final URL url = getResourceRelative(name, context);
          if (url == null) {
              return null;
          }
  
          try {
              return url.openStream();
          }
          catch (IOException e) {
              return null;
          }
      }
  
      /**
       * Tries to create a new instance of the given class. This is a short cut
       * for the common bean instantiation code.
       *
       * @param className the class name as String, never null.
       * @param source    the source class, from where to get the classloader.
       * @return the instantiated object or null, if an error occured.
       */
      public static Object loadAndInstantiate(final String className,
                                              final Class source) {
          try {
              final ClassLoader loader = getClassLoader(source);
              final Class c = loader.loadClass(className);
              return c.newInstance();
          }
          catch (Exception e) {
              return null;
          }
      }
  
      /**
       * Tries to create a new instance of the given class. This is a short cut
       * for the common bean instantiation code. This method is a type-safe method
       * and will not instantiate the class unless it is an instance of the given
       * type.
       *
       * @param className the class name as String, never null.
       * @param source    the source class, from where to get the classloader.
       * @param type  the type.
       * @return the instantiated object or null, if an error occurred.
       */
      public static Object loadAndInstantiate(final String className,
                                              final Class source,
                                              final Class type) {
          try {
              final ClassLoader loader = getClassLoader(source);
              final Class c = loader.loadClass(className);
              if (type.isAssignableFrom(c)) {
                  return c.newInstance();
              }
          }
          catch (Exception e) {
              return null;
          }
          return null;
      }
  
      /**
       * Returns <code>true</code> if this is version 1.4 or later of the
       * Java runtime.
       *
       * @return A boolean.
       */
      public static boolean isJDK14() {
          try {
            final ClassLoader loader = getClassLoader(ObjectUtilities.class);
            if (loader != null) {
                try {
                  loader.loadClass("java.util.RandomAccess");
                  return true;
                }
                catch (ClassNotFoundException e) {
                  return false;
                }
                catch(Exception e) {
                  // do nothing, but do not crash ...
                }
            }
          }
          catch (Exception e) {
            // cant do anything about it, we have to accept and ignore it ..
          }
  
          // OK, the quick and dirty, but secure way failed. Lets try it
          // using the standard way.
          try {
              final String version = System.getProperty
                      ("java.vm.specification.version");
              // parse the beast...
              if (version == null) {
                  return false;
              }
  
              String[] versions = parseVersions(version);
              String[] target = new String[]{ "1", "4" };
              return (ArrayUtilities.compareVersionArrays(versions, target) >= 0);
          }
          catch(Exception e) {
              return false;
          }
      }
  
      private static String[] parseVersions (String version)
      {
        if (version == null)
        {
          return new String[0];
        }
  
        final ArrayList versions = new ArrayList();
        final StringTokenizer strtok = new StringTokenizer(version, ".");
        while (strtok.hasMoreTokens())
        {
          versions.add (strtok.nextToken());
        }
        return (String[]) versions.toArray(new String[versions.size()]);
      }
  }
  