f475867806
* java/util/prefs/Preferences.java (defaultFactoryClass): Fixed class name. (getFactory): Create instance of class returned by Class.forName(), reformated code. From-SVN: r72229
671 lines
28 KiB
Java
671 lines
28 KiB
Java
/* Preferences - Preference node containing key value entries and subnodes
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Copyright (C) 2001 Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package java.util.prefs;
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import java.io.InputStream;
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import java.io.OutputStream;
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import java.io.IOException;
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import java.security.AccessController;
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import java.security.Permission;
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import java.security.PrivilegedAction;
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import gnu.java.util.prefs.*;
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/**
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* Preference node containing key value entries and subnodes.
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* <p>
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* There are two preference node trees, a system tree which can be accessed
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* by calling <code>systemRoot()</code> containing system preferences usefull
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* for all users, and a user tree that can be accessed by calling
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* <code>userRoot()</code> containing preferences that can differ between
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* different users. How different users are identified is implementation
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* depended. It can be determined by Thread, Access Control Context or Subject.
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* <p>
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* This implementation uses the "java.util.prefs.PreferencesFactory" system
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* property to find a class that implement <code>PreferencesFactory</code>
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* and initialized that class (if it has a public no arguments contructor)
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* to get at the actual system or user root. If the system property is not set,
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* or the class cannot be initialized it uses the default implementation
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* <code>gnu.java.util.prefs.FileBasedFactory</code>.
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* <p>
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* Besides the two static method above to get the roots of the system and user
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* preference node trees there are also two convenience methods to access the
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* default preference node for a particular package an object is in. These are
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* <code>userNodeForPackage()</code> and <code>systemNodeForPackage()</code>.
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* Both methods take an Object as an argument so accessing preferences values
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* can be as easy as calling <code>Preferences.userNodeForPackage(this)</code>.
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* <p>
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* Note that if a security manager is installed all static methods check for
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* <code>RuntimePermission("preferences")</code>. But if this permission is
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* given to the code then it can access and change all (user) preference nodes
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* and entries. So you should be carefull not to store to sensitive information
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* or make security decissions based on preference values since there is no
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* more fine grained control over what preference values can be changed once
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* code has been given the correct runtime permission.
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* <p>
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* XXX
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*
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* @since 1.4
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* @author Mark Wielaard (mark@klomp.org)
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*/
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public abstract class Preferences {
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// Static Fields
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/**
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* Default PreferencesFactory class used when the system property
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* "java.util.prefs.PreferencesFactory" is not set.
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* <p>
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* XXX - Currently set to MemoryBasedFactory, should be changed
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* when FileBasedPreferences backend works.
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*/
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private static final String defaultFactoryClass
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= "gnu.java.util.prefs.MemoryBasedFactory";
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/** Permission needed to access system or user root. */
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private static final Permission prefsPermission
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= new RuntimePermission("preferences");
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/**
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* The preferences factory object that supplies the system and user root.
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* Set and returned by the getFactory() method.
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*/
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private static PreferencesFactory factory;
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/** Maximum node name length. 80 characters. */
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public static final int MAX_NAME_LENGTH = 80;
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/** Maximum entry key length. 80 characters. */
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public static final int MAX_KEY_LENGTH = 80;
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/** Maximum entry value length. 8192 characters. */
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public static final int MAX_VALUE_LENGTH = 8192;
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// Constructors
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/**
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* Creates a new Preferences node. Can only be used by subclasses.
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* Empty implementation.
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*/
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protected Preferences() {}
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// Static methods
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/**
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* Returns the system preferences root node containing usefull preferences
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* for all users. It is save to cache this value since it should always
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* return the same preference node.
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*
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* @return the root system preference node
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* @exception SecurityException when a security manager is installed and
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* the caller does not have <code>RuntimePermission("preferences")</code>.
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*/
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public static Preferences systemRoot() throws SecurityException {
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// Get the preferences factory and check for permission
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PreferencesFactory factory = getFactory();
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return factory.systemRoot();
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}
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/**
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* Returns the user preferences root node containing preferences for the
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* the current user. How different users are identified is implementation
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* depended. It can be determined by Thread, Access Control Context or
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* Subject.
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*
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* @return the root user preference node
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* @exception SecurityException when a security manager is installed and
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* the caller does not have <code>RuntimePermission("preferences")</code>.
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*/
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public static Preferences userRoot() throws SecurityException {
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// Get the preferences factory and check for permission
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PreferencesFactory factory = getFactory();
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return factory.userRoot();
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}
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/**
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* Private helper method for <code>systemRoot()</code> and
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* <code>userRoot()</code>. Checks security permission and instantiates the
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* correct factory if it has not yet been set.
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* <p>
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* When the preferences factory has not yet been set this method first
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* tries to get the system propery "java.util.prefs.PreferencesFactory"
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* and tries to initializes that class. If the system property is not set
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* or initialization fails it returns an instance of the default factory
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* <code>gnu.java.util.prefs.FileBasedPreferencesFactory</code>.
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*
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* @return the preferences factory to use
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* @exception SecurityException when a security manager is installed and
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* the caller does not have <code>RuntimePermission("preferences")</code>.
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*/
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private static PreferencesFactory getFactory() throws SecurityException {
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// First check for permission
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SecurityManager sm = System.getSecurityManager();
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if (sm != null) {
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sm.checkPermission(prefsPermission);
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}
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// Get the factory
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if (factory == null) {
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// Caller might not have enough permissions
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factory = (PreferencesFactory) AccessController.doPrivileged(
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new PrivilegedAction() {
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public Object run() {
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PreferencesFactory pf = null;
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String className = System.getProperty
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("java.util.prefs.PreferencesFactory");
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if (className != null) {
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try {
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Class fc = Class.forName(className);
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Object o = fc.newInstance();
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pf = (PreferencesFactory) o;
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} catch (ClassNotFoundException cnfe)
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{/*ignore*/}
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catch (InstantiationException ie)
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{/*ignore*/}
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catch (IllegalAccessException iae)
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{/*ignore*/}
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catch (ClassCastException cce)
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{/*ignore*/}
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}
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return pf;
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}
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});
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// Still no factory? Use our default.
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if (factory == null)
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{
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try
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{
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Class cls = Class.forName (defaultFactoryClass);
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factory = (PreferencesFactory) cls.newInstance();
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}
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catch (Exception e)
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{
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throw new RuntimeException ("Couldn't load default factory"
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+ " '"+ defaultFactoryClass +"'");
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// XXX - when using 1.4 compatible throwables add cause
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}
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}
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}
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return factory;
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}
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/**
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* Returns the system preferences node for the package of an object.
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* The package node name of the object is determined by dropping the
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* class name of the object of the fully quallified class name and
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* replacing all '.' to '/' in the package name. If the class of the
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* object has no package then the package node name is "<unnamed>".
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* The returened node is <code>systemRoot().node(packageNodeName)</code>.
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*
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* @param o Object whose default system preference node is requested
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* @returns system preferences node that should be used by object o
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* @exception SecurityException when a security manager is installed and
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* the caller does not have <code>RuntimePermission("preferences")</code>.
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*/
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public static Preferences systemNodeForPackage(Class c)
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throws SecurityException
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{
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return nodeForPackage(c, systemRoot());
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}
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/**
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* Returns the user preferences node for the package of an object.
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* The package node name of the object is determined by dropping the
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* class name of the object of the fully quallified class name and
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* replacing all '.' to '/' in the package name. If the class of the
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* object has no package then the package node name is "<unnamed>".
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* The returened node is <code>userRoot().node(packageNodeName)</code>.
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*
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* @param o Object whose default user preference node is requested
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* @returns user preferences node that should be used by object o
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* @exception SecurityException when a security manager is installed and
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* the caller does not have <code>RuntimePermission("preferences")</code>.
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*/
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public static Preferences userNodeForPackage(Class c)
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throws SecurityException
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{
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return nodeForPackage(c, userRoot());
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}
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/**
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* Private helper method for <code>systemNodeForPackage()</code> and
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* <code>userNodeForPackage()</code>. Given the correct system or user
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* root it returns the correct Preference node for the package node name
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* of the given object.
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*/
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private static Preferences nodeForPackage(Class c, Preferences root) {
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// Get the package path
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String className = c.getName();
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String packagePath;
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int index = className.lastIndexOf('.');
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if(index == -1) {
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packagePath = "<unnamed>";
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} else {
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packagePath = className.substring(0,index).replace('.','/');
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}
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return root.node(packagePath);
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}
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/**
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* XXX
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*/
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public static void importPreferences(InputStream is)
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throws InvalidPreferencesFormatException,
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IOException
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{
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PreferencesFactory factory = getFactory();
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NodeReader reader = new NodeReader(is, factory);
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reader.importPreferences();
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}
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// abstract methods (identification)
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/**
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* Returns the absolute path name of this preference node.
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* The absolute path name of a node is the path name of its parent node
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* plus a '/' plus its own name. If the node is the root node and has no
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* parent then its name is "" and its absolute path name is "/".
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*/
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abstract public String absolutePath();
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/**
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* Returns true if this node comes from the user preferences tree, false
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* if it comes from the system preferences tree.
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*/
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abstract public boolean isUserNode();
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/**
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* Returns the name of this preferences node. The name of the node cannot
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* be null, can be mostly 80 characters and cannot contain any '/'
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* characters. The root node has as name "".
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*/
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abstract public String name();
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/**
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* Returns the String given by
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* <code>
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* (isUserNode() ? "User":"System") + " Preference Node: " + absolutePath()
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* </code>
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*/
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abstract public String toString();
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// abstract methods (navigation)
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/**
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* Returns all the direct sub nodes of this preferences node.
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* Needs access to the backing store to give a meaningfull answer.
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*
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* @exception BackingStoreException when the backing store cannot be
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* reached
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* @exception IllegalStateException when this node has been removed
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*/
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abstract public String[] childrenNames() throws BackingStoreException;
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/**
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* Returns a sub node of this preferences node if the given path is
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* relative (does not start with a '/') or a sub node of the root
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* if the path is absolute (does start with a '/').
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*
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* @exception IllegalStateException if this node has been removed
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* @exception IllegalArgumentException if the path contains two or more
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* consecutive '/' characters, ends with a '/' charactor and is not the
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* string "/" (indicating the root node) or any name on the path is more
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* then 80 characters long
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*/
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abstract public Preferences node(String path);
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/**
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* Returns true if the node that the path points to exists in memory or
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* in the backing store. Otherwise it returns false or an exception is
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* thrown. When this node is removed the only valid parameter is the
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* empty string (indicating this node), the return value in that case
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* will be false.
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*
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* @exception BackingStoreException when the backing store cannot be
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* reached
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* @exception IllegalStateException if this node has been removed
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* and the path is not the empty string (indicating this node)
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* @exception IllegalArgumentException if the path contains two or more
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* consecutive '/' characters, ends with a '/' charactor and is not the
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* string "/" (indicating the root node) or any name on the path is more
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* then 80 characters long
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*/
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abstract public boolean nodeExists(String path)
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throws BackingStoreException;
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/**
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* Returns the parent preferences node of this node or null if this is
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* the root of the preferences tree.
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*
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* @exception IllegalStateException if this node has been removed
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*/
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abstract public Preferences parent();
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// abstract methods (export)
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/**
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* XXX
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*/
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abstract public void exportNode(OutputStream os)
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throws BackingStoreException,
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IOException;
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/**
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* XXX
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*/
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abstract public void exportSubtree(OutputStream os)
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throws BackingStoreException,
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IOException;
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// abstract methods (preference entry manipulation)
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/**
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* Returns an (possibly empty) array with all the keys of the preference
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* entries of this node.
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*
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* @exception BackingStoreException when the backing store cannot be
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* reached
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* @exception IllegalStateException if this node has been removed
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*/
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abstract public String[] keys() throws BackingStoreException;
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/**
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* Returns the value associated with the key in this preferences node. If
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* the default value of the key cannot be found in the preferences node
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* entries or something goes wrong with the backing store the supplied
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* default value is returned.
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*
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* @exception IllegalArgumentException if key is larger then 80 characters
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* @exception IllegalStateException if this node has been removed
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* @exception NullPointerException if key is null
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*/
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abstract public String get(String key, String defaultVal);
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/**
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* Convenience method for getting the given entry as a boolean.
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* When the string representation of the requested entry is either
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* "true" or "false" (ignoring case) then that value is returned,
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* otherwise the given default boolean value is returned.
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*
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* @exception IllegalArgumentException if key is larger then 80 characters
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* @exception IllegalStateException if this node has been removed
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* @exception NullPointerException if key is null
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*/
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abstract public boolean getBoolean(String key, boolean defaultVal);
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/**
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* Convenience method for getting the given entry as a byte array.
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* When the string representation of the requested entry is a valid
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* Base64 encoded string (without any other characters, such as newlines)
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* then the decoded Base64 string is returned as byte array,
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* otherwise the given default byte array value is returned.
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*
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* @exception IllegalArgumentException if key is larger then 80 characters
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* @exception IllegalStateException if this node has been removed
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* @exception NullPointerException if key is null
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*/
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abstract public byte[] getByteArray(String key, byte[] defaultVal);
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/**
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* Convenience method for getting the given entry as a double.
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* When the string representation of the requested entry can be decoded
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* with <code>Double.parseDouble()</code> then that double is returned,
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* otherwise the given default double value is returned.
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*
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* @exception IllegalArgumentException if key is larger then 80 characters
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* @exception IllegalStateException if this node has been removed
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* @exception NullPointerException if key is null
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*/
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abstract public double getDouble(String key, double defaultVal);
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/**
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* Convenience method for getting the given entry as a float.
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* When the string representation of the requested entry can be decoded
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* with <code>Float.parseFloat()</code> then that float is returned,
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* otherwise the given default float value is returned.
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*
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* @exception IllegalArgumentException if key is larger then 80 characters
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* @exception IllegalStateException if this node has been removed
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* @exception NullPointerException if key is null
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*/
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abstract public float getFloat(String key, float defaultVal);
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/**
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* Convenience method for getting the given entry as an integer.
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* When the string representation of the requested entry can be decoded
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* with <code>Integer.parseInt()</code> then that integer is returned,
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* otherwise the given default integer value is returned.
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*
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* @exception IllegalArgumentException if key is larger then 80 characters
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* @exception IllegalStateException if this node has been removed
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* @exception NullPointerException if key is null
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*/
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abstract public int getInt(String key, int defaultVal);
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/**
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* Convenience method for getting the given entry as a long.
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* When the string representation of the requested entry can be decoded
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* with <code>Long.parseLong()</code> then that long is returned,
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* otherwise the given default long value is returned.
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*
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* @exception IllegalArgumentException if key is larger then 80 characters
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* @exception IllegalStateException if this node has been removed
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* @exception NullPointerException if key is null
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*/
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abstract public long getLong(String key, long defaultVal);
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/**
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* Sets the value of the given preferences entry for this node.
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* Key and value cannot be null, the key cannot exceed 80 characters
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* and the value cannot exceed 8192 characters.
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* <p>
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* The result will be immediatly visible in this VM, but may not be
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* immediatly written to the backing store.
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*
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* @exception NullPointerException if either key or value are null
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* @exception IllegalArgumentException if either key or value are to large
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* @exception IllegalStateException when this node has been removed
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*/
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abstract public void put(String key, String value);
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/**
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* Convenience method for setting the given entry as a boolean.
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* The boolean is converted with <code>Boolean.toString(value)</code>
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* and then stored in the preference entry as that string.
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*
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* @exception NullPointerException if key is null
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* @exception IllegalArgumentException if the key length is to large
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* @exception IllegalStateException when this node has been removed
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*/
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abstract public void putBoolean(String key, boolean value);
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|
|
/**
|
|
* Convenience method for setting the given entry as an array of bytes.
|
|
* The byte array is converted to a Base64 encoded string
|
|
* and then stored in the preference entry as that string.
|
|
* <p>
|
|
* Note that a byte array encoded as a Base64 string will be about 1.3
|
|
* times larger then the original length of the byte array, which means
|
|
* that the byte array may not be larger about 6 KB.
|
|
*
|
|
* @exception NullPointerException if either key or value are null
|
|
* @exception IllegalArgumentException if either key or value are to large
|
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* @exception IllegalStateException when this node has been removed
|
|
*/
|
|
abstract public void putByteArray(String key, byte[] value);
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|
|
|
/**
|
|
* Convenience method for setting the given entry as a double.
|
|
* The double is converted with <code>Double.toString(double)</code>
|
|
* and then stored in the preference entry as that string.
|
|
*
|
|
* @exception NullPointerException if the key is null
|
|
* @exception IllegalArgumentException if the key length is to large
|
|
* @exception IllegalStateException when this node has been removed
|
|
*/
|
|
abstract public void putDouble(String key, double value);
|
|
|
|
/**
|
|
* Convenience method for setting the given entry as a float.
|
|
* The float is converted with <code>Float.toString(float)</code>
|
|
* and then stored in the preference entry as that string.
|
|
*
|
|
* @exception NullPointerException if the key is null
|
|
* @exception IllegalArgumentException if the key length is to large
|
|
* @exception IllegalStateException when this node has been removed
|
|
*/
|
|
abstract public void putFloat(String key, float value);
|
|
|
|
/**
|
|
* Convenience method for setting the given entry as an integer.
|
|
* The integer is converted with <code>Integer.toString(int)</code>
|
|
* and then stored in the preference entry as that string.
|
|
*
|
|
* @exception NullPointerException if the key is null
|
|
* @exception IllegalArgumentException if the key length is to large
|
|
* @exception IllegalStateException when this node has been removed
|
|
*/
|
|
abstract public void putInt(String key, int value);
|
|
|
|
/**
|
|
* Convenience method for setting the given entry as a long.
|
|
* The long is converted with <code>Long.toString(long)</code>
|
|
* and then stored in the preference entry as that string.
|
|
*
|
|
* @exception NullPointerException if the key is null
|
|
* @exception IllegalArgumentException if the key length is to large
|
|
* @exception IllegalStateException when this node has been removed
|
|
*/
|
|
abstract public void putLong(String key, long value);
|
|
|
|
/**
|
|
* Removes the preferences entry from this preferences node.
|
|
* <p>
|
|
* The result will be immediatly visible in this VM, but may not be
|
|
* immediatly written to the backing store.
|
|
*
|
|
* @exception NullPointerException if the key is null
|
|
* @exception IllegalArgumentException if the key length is to large
|
|
* @exception IllegalStateException when this node has been removed
|
|
*/
|
|
abstract public void remove(String key);
|
|
|
|
// abstract methods (preference node manipulation)
|
|
|
|
/**
|
|
* Removes all entries from this preferences node. May need access to the
|
|
* backing store to get and clear all entries.
|
|
* <p>
|
|
* The result will be immediatly visible in this VM, but may not be
|
|
* immediatly written to the backing store.
|
|
*
|
|
* @exception BackingStoreException when the backing store cannot be
|
|
* reached
|
|
* @exception IllegalStateException if this node has been removed
|
|
*/
|
|
abstract public void clear() throws BackingStoreException;
|
|
|
|
/**
|
|
* Writes all preference changes on this and any subnode that have not
|
|
* yet been written to the backing store. This has no effect on the
|
|
* preference entries in this VM, but it makes sure that all changes
|
|
* are visible to other programs (other VMs might need to call the
|
|
* <code>sync()</code> method to actually see the changes to the backing
|
|
* store.
|
|
*
|
|
* @exception BackingStoreException when the backing store cannot be
|
|
* reached
|
|
* @exception IllegalStateException if this node has been removed
|
|
*/
|
|
abstract public void flush() throws BackingStoreException;
|
|
|
|
/**
|
|
* Writes and reads all preference changes to and from this and any
|
|
* subnodes. This makes sure that all local changes are written to the
|
|
* backing store and that all changes to the backing store are visible
|
|
* in this preference node (and all subnodes).
|
|
*
|
|
* @exception BackingStoreException when the backing store cannot be
|
|
* reached
|
|
* @exception IllegalStateException if this node has been removed
|
|
*/
|
|
abstract public void sync() throws BackingStoreException;
|
|
|
|
/**
|
|
* Removes this and all subnodes from the backing store and clears all
|
|
* entries. After removal this instance will not be useable (except for
|
|
* a few methods that don't throw a <code>InvalidStateException</code>),
|
|
* even when a new node with the same path name is created this instance
|
|
* will not be usable again. The root (system or user) may never be removed.
|
|
* <p>
|
|
* Note that according to the specification an implementation may delay
|
|
* removal of the node from the backing store till the <code>flush()</code>
|
|
* method is called. But the <code>flush()</code> method may throw a
|
|
* <code>IllegalStateException</code> when the node has been removed.
|
|
* So most implementations will actually remove the node and any subnodes
|
|
* from the backing store immediatly.
|
|
*
|
|
* @exception BackingStoreException when the backing store cannot be
|
|
* reached
|
|
* @exception IllegalStateException if this node has already been removed
|
|
* @exception UnsupportedOperationException if this is a root node
|
|
*/
|
|
abstract public void removeNode() throws BackingStoreException;
|
|
|
|
// abstract methods (listeners)
|
|
|
|
abstract public void addNodeChangeListener(NodeChangeListener listener);
|
|
|
|
abstract public void addPreferenceChangeListener
|
|
(PreferenceChangeListener listener);
|
|
|
|
abstract public void removeNodeChangeListener(NodeChangeListener listener);
|
|
|
|
abstract public void removePreferenceChangeListener
|
|
(PreferenceChangeListener listener);
|
|
|
|
}
|
|
|