org.jfree.util.ObjectUtilities Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of jcommon Show documentation
Show all versions of jcommon Show documentation
JCommon is a free general purpose Java class library that is used in
several projects at www.jfree.org, including JFreeChart and
JFreeReport.
/* ========================================================================
* 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.
*
* 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 true if the two objects are equal OR both
* null.
*
* @param o1 object 1 (null permitted).
* @param o2 object 2 (null permitted).
* @return true or false.
*/
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
* null.
*
* @param object the object (null permitted).
* @return The object's hash code (or zero if the object is
* null).
*/
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 (null 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 (null 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 absolute 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 relative 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
* absolute 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
* relative 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 true 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()]);
}
}
© 2015 - 2024 Weber Informatics LLC | Privacy Policy