mirror of git://gcc.gnu.org/git/gcc.git
697 lines
30 KiB
Java
697 lines
30 KiB
Java
/* Preferences -- Preference node containing key value entries and subnodes
|
|
Copyright (C) 2001, 2004, 2005, 2006 Free Software Foundation, Inc.
|
|
|
|
This file is part of GNU Classpath.
|
|
|
|
GNU Classpath is free software; you can redistribute it and/or modify
|
|
it under the terms of the GNU General Public License as published by
|
|
the Free Software Foundation; either version 2, or (at your option)
|
|
any later version.
|
|
|
|
GNU Classpath 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
|
|
General Public License for more details.
|
|
|
|
You should have received a copy of the GNU General Public License
|
|
along with GNU Classpath; see the file COPYING. If not, write to the
|
|
Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
|
|
02110-1301 USA.
|
|
|
|
Linking this library statically or dynamically with other modules is
|
|
making a combined work based on this library. Thus, the terms and
|
|
conditions of the GNU General Public License cover the whole
|
|
combination.
|
|
|
|
As a special exception, the copyright holders of this library give you
|
|
permission to link this library with independent modules to produce an
|
|
executable, regardless of the license terms of these independent
|
|
modules, and to copy and distribute the resulting executable under
|
|
terms of your choice, provided that you also meet, for each linked
|
|
independent module, the terms and conditions of the license of that
|
|
module. An independent module is a module which is not derived from
|
|
or based on this library. If you modify this library, you may extend
|
|
this exception to your version of the library, but you are not
|
|
obligated to do so. If you do not wish to do so, delete this
|
|
exception statement from your version. */
|
|
|
|
package java.util.prefs;
|
|
|
|
import gnu.classpath.ServiceFactory;
|
|
import gnu.java.util.prefs.NodeReader;
|
|
|
|
import java.io.IOException;
|
|
import java.io.InputStream;
|
|
import java.io.OutputStream;
|
|
import java.security.AccessController;
|
|
import java.security.Permission;
|
|
import java.security.PrivilegedAction;
|
|
import java.util.Iterator;
|
|
|
|
/**
|
|
* Preference node containing key value entries and subnodes.
|
|
* <p>
|
|
* There are two preference node trees, a system tree which can be accessed
|
|
* by calling <code>systemRoot()</code> containing system preferences usefull
|
|
* for all users, and a user tree that can be accessed by calling
|
|
* <code>userRoot()</code> containing preferences that can differ between
|
|
* different users. How different users are identified is implementation
|
|
* depended. It can be determined by Thread, Access Control Context or Subject.
|
|
* <p>
|
|
* This implementation uses the "java.util.prefs.PreferencesFactory" system
|
|
* property to find a class that implement <code>PreferencesFactory</code>
|
|
* and initialized that class (if it has a public no arguments contructor)
|
|
* to get at the actual system or user root. If the system property is not set,
|
|
* or the class cannot be initialized it uses the default implementation
|
|
* <code>gnu.java.util.prefs.FileBasedFactory</code>.
|
|
* <p>
|
|
* Besides the two static method above to get the roots of the system and user
|
|
* preference node trees there are also two convenience methods to access the
|
|
* default preference node for a particular package an object is in. These are
|
|
* <code>userNodeForPackage()</code> and <code>systemNodeForPackage()</code>.
|
|
* Both methods take an Object as an argument so accessing preferences values
|
|
* can be as easy as calling <code>Preferences.userNodeForPackage(this)</code>.
|
|
* <p>
|
|
* Note that if a security manager is installed all static methods check for
|
|
* <code>RuntimePermission("preferences")</code>. But if this permission is
|
|
* given to the code then it can access and change all (user) preference nodes
|
|
* and entries. So you should be carefull not to store to sensitive information
|
|
* or make security decissions based on preference values since there is no
|
|
* more fine grained control over what preference values can be changed once
|
|
* code has been given the correct runtime permission.
|
|
* <p>
|
|
* XXX
|
|
*
|
|
* @since 1.4
|
|
* @author Mark Wielaard (mark@klomp.org)
|
|
*/
|
|
public abstract class Preferences {
|
|
|
|
// Static Fields
|
|
|
|
/**
|
|
* Default PreferencesFactory class used when the system property
|
|
* "java.util.prefs.PreferencesFactory" is not set.
|
|
*/
|
|
private static final String defaultFactoryClass
|
|
= "gnu.java.util.prefs.FileBasedFactory";
|
|
|
|
/** Permission needed to access system or user root. */
|
|
private static final Permission prefsPermission
|
|
= new RuntimePermission("preferences");
|
|
|
|
/**
|
|
* The preferences factory object that supplies the system and user root.
|
|
* Set and returned by the getFactory() method.
|
|
*/
|
|
private static PreferencesFactory factory;
|
|
|
|
/** Maximum node name length. 80 characters. */
|
|
public static final int MAX_NAME_LENGTH = 80;
|
|
|
|
/** Maximum entry key length. 80 characters. */
|
|
public static final int MAX_KEY_LENGTH = 80;
|
|
|
|
/** Maximum entry value length. 8192 characters. */
|
|
public static final int MAX_VALUE_LENGTH = 8192;
|
|
|
|
// Constructors
|
|
|
|
/**
|
|
* Creates a new Preferences node. Can only be used by subclasses.
|
|
* Empty implementation.
|
|
*/
|
|
protected Preferences() {}
|
|
|
|
// Static methods
|
|
|
|
/**
|
|
* Returns the system preferences root node containing usefull preferences
|
|
* for all users. It is save to cache this value since it should always
|
|
* return the same preference node.
|
|
*
|
|
* @return the root system preference node
|
|
* @exception SecurityException when a security manager is installed and
|
|
* the caller does not have <code>RuntimePermission("preferences")</code>.
|
|
*/
|
|
public static Preferences systemRoot() throws SecurityException {
|
|
// Get the preferences factory and check for permission
|
|
PreferencesFactory factory = getFactory();
|
|
|
|
return factory.systemRoot();
|
|
}
|
|
|
|
/**
|
|
* Returns the user preferences root node containing preferences for the
|
|
* the current user. How different users are identified is implementation
|
|
* depended. It can be determined by Thread, Access Control Context or
|
|
* Subject.
|
|
*
|
|
* @return the root user preference node
|
|
* @exception SecurityException when a security manager is installed and
|
|
* the caller does not have <code>RuntimePermission("preferences")</code>.
|
|
*/
|
|
public static Preferences userRoot() throws SecurityException {
|
|
// Get the preferences factory and check for permission
|
|
PreferencesFactory factory = getFactory();
|
|
return factory.userRoot();
|
|
}
|
|
|
|
/**
|
|
* Private helper method for <code>systemRoot()</code> and
|
|
* <code>userRoot()</code>. Checks security permission and instantiates the
|
|
* correct factory if it has not yet been set.
|
|
* <p>
|
|
* When the preferences factory has not yet been set this method first
|
|
* tries to get the system propery "java.util.prefs.PreferencesFactory"
|
|
* and tries to initializes that class. If the system property is not set
|
|
* or initialization fails it returns an instance of the default factory
|
|
* <code>gnu.java.util.prefs.FileBasedPreferencesFactory</code>.
|
|
*
|
|
* @return the preferences factory to use
|
|
* @exception SecurityException when a security manager is installed and
|
|
* the caller does not have <code>RuntimePermission("preferences")</code>.
|
|
*/
|
|
private static PreferencesFactory getFactory() throws SecurityException {
|
|
|
|
// First check for permission
|
|
SecurityManager sm = System.getSecurityManager();
|
|
if (sm != null) {
|
|
sm.checkPermission(prefsPermission);
|
|
}
|
|
|
|
// Get the factory
|
|
if (factory == null) {
|
|
// Caller might not have enough permissions
|
|
factory = AccessController.doPrivileged(
|
|
new PrivilegedAction<PreferencesFactory>() {
|
|
public PreferencesFactory run() {
|
|
PreferencesFactory pf = null;
|
|
String className = System.getProperty
|
|
("java.util.prefs.PreferencesFactory");
|
|
if (className != null) {
|
|
try {
|
|
Class fc = Class.forName(className);
|
|
Object o = fc.newInstance();
|
|
pf = (PreferencesFactory) o;
|
|
} catch (ClassNotFoundException cnfe)
|
|
{/*ignore*/}
|
|
catch (InstantiationException ie)
|
|
{/*ignore*/}
|
|
catch (IllegalAccessException iae)
|
|
{/*ignore*/}
|
|
catch (ClassCastException cce)
|
|
{/*ignore*/}
|
|
}
|
|
return pf;
|
|
}
|
|
});
|
|
|
|
// Still no factory? Try to see if we have one defined
|
|
// as a System Preference
|
|
if (factory == null)
|
|
{
|
|
Iterator iter = ServiceFactory.lookupProviders
|
|
(PreferencesFactory.class, null);
|
|
|
|
if (iter != null && iter.hasNext())
|
|
factory = (PreferencesFactory) iter.next();
|
|
}
|
|
|
|
// Still no factory? Use our default.
|
|
if (factory == null)
|
|
{
|
|
try
|
|
{
|
|
Class cls = Class.forName (defaultFactoryClass);
|
|
factory = (PreferencesFactory) cls.newInstance();
|
|
}
|
|
catch (Exception e)
|
|
{
|
|
throw new RuntimeException ("Couldn't load default factory"
|
|
+ " '"+ defaultFactoryClass +"'", e);
|
|
}
|
|
}
|
|
|
|
}
|
|
|
|
return factory;
|
|
}
|
|
|
|
/**
|
|
* Returns the system preferences node for the package of a class.
|
|
* The package node name of the class is determined by dropping the
|
|
* final component of the fully qualified class name and
|
|
* changing all '.' to '/' in the package name. If the class of the
|
|
* object has no package then the package node name is "<unnamed>".
|
|
* The returned node is <code>systemRoot().node(packageNodeName)</code>.
|
|
*
|
|
* @param c Object whose default system preference node is requested
|
|
* @returns system preferences node that should be used by class c
|
|
* @exception SecurityException when a security manager is installed and
|
|
* the caller does not have <code>RuntimePermission("preferences")</code>.
|
|
*/
|
|
public static Preferences systemNodeForPackage(Class<?> c)
|
|
throws SecurityException
|
|
{
|
|
return nodeForPackage(c, systemRoot());
|
|
}
|
|
|
|
/**
|
|
* Returns the user preferences node for the package of a class.
|
|
* The package node name of the class is determined by dropping the
|
|
* final component of the fully qualified class name and
|
|
* changing all '.' to '/' in the package name. If the class of the
|
|
* object has no package then the package node name is "<unnamed>".
|
|
* The returned node is <code>userRoot().node(packageNodeName)</code>.
|
|
*
|
|
* @param c Object whose default userpreference node is requested
|
|
* @returns userpreferences node that should be used by class c
|
|
* @exception SecurityException when a security manager is installed and
|
|
* the caller does not have <code>RuntimePermission("preferences")</code>.
|
|
*/
|
|
public static Preferences userNodeForPackage(Class<?> c)
|
|
throws SecurityException
|
|
{
|
|
return nodeForPackage(c, userRoot());
|
|
}
|
|
|
|
/**
|
|
* Private helper method for <code>systemNodeForPackage()</code> and
|
|
* <code>userNodeForPackage()</code>. Given the correct system or user
|
|
* root it returns the correct Preference node for the package node name
|
|
* of the given object.
|
|
*/
|
|
private static Preferences nodeForPackage(Class c, Preferences root) {
|
|
// Get the package path
|
|
String className = c.getName();
|
|
String packagePath;
|
|
int index = className.lastIndexOf('.');
|
|
if(index == -1) {
|
|
packagePath = "<unnamed>";
|
|
} else {
|
|
packagePath = className.substring(0,index).replace('.','/');
|
|
}
|
|
|
|
return root.node(packagePath);
|
|
}
|
|
|
|
/**
|
|
* Import preferences from the given input stream. This expects
|
|
* preferences to be represented in XML as emitted by
|
|
* {@link #exportNode(OutputStream)} and
|
|
* {@link #exportSubtree(OutputStream)}.
|
|
* @throws IOException if there is an error while reading
|
|
* @throws InvalidPreferencesFormatException if the XML is not properly
|
|
* formatted
|
|
*/
|
|
public static void importPreferences(InputStream is)
|
|
throws InvalidPreferencesFormatException,
|
|
IOException
|
|
{
|
|
PreferencesFactory factory = getFactory();
|
|
NodeReader reader = new NodeReader(is, factory);
|
|
reader.importPreferences();
|
|
}
|
|
|
|
// abstract methods (identification)
|
|
|
|
/**
|
|
* Returns the absolute path name of this preference node.
|
|
* The absolute path name of a node is the path name of its parent node
|
|
* plus a '/' plus its own name. If the node is the root node and has no
|
|
* parent then its name is "" and its absolute path name is "/".
|
|
*/
|
|
public abstract String absolutePath();
|
|
|
|
/**
|
|
* Returns true if this node comes from the user preferences tree, false
|
|
* if it comes from the system preferences tree.
|
|
*/
|
|
public abstract boolean isUserNode();
|
|
|
|
/**
|
|
* Returns the name of this preferences node. The name of the node cannot
|
|
* be null, can be mostly 80 characters and cannot contain any '/'
|
|
* characters. The root node has as name "".
|
|
*/
|
|
public abstract String name();
|
|
|
|
/**
|
|
* Returns the String given by
|
|
* <code>
|
|
* (isUserNode() ? "User":"System") + " Preference Node: " + absolutePath()
|
|
* </code>
|
|
*/
|
|
public abstract String toString();
|
|
|
|
// abstract methods (navigation)
|
|
|
|
/**
|
|
* Returns all the direct sub nodes of this preferences node.
|
|
* Needs access to the backing store to give a meaningfull answer.
|
|
*
|
|
* @exception BackingStoreException when the backing store cannot be
|
|
* reached
|
|
* @exception IllegalStateException when this node has been removed
|
|
*/
|
|
public abstract String[] childrenNames() throws BackingStoreException;
|
|
|
|
/**
|
|
* Returns a sub node of this preferences node if the given path is
|
|
* relative (does not start with a '/') or a sub node of the root
|
|
* if the path is absolute (does start with a '/').
|
|
*
|
|
* @exception IllegalStateException if this node has been removed
|
|
* @exception IllegalArgumentException if the path contains two or more
|
|
* consecutive '/' characters, ends with a '/' charactor and is not the
|
|
* string "/" (indicating the root node) or any name on the path is more
|
|
* then 80 characters long
|
|
*/
|
|
public abstract Preferences node(String path);
|
|
|
|
/**
|
|
* Returns true if the node that the path points to exists in memory or
|
|
* in the backing store. Otherwise it returns false or an exception is
|
|
* thrown. When this node is removed the only valid parameter is the
|
|
* empty string (indicating this node), the return value in that case
|
|
* will be false.
|
|
*
|
|
* @exception BackingStoreException when the backing store cannot be
|
|
* reached
|
|
* @exception IllegalStateException if this node has been removed
|
|
* and the path is not the empty string (indicating this node)
|
|
* @exception IllegalArgumentException if the path contains two or more
|
|
* consecutive '/' characters, ends with a '/' charactor and is not the
|
|
* string "/" (indicating the root node) or any name on the path is more
|
|
* then 80 characters long
|
|
*/
|
|
public abstract boolean nodeExists(String path)
|
|
throws BackingStoreException;
|
|
|
|
/**
|
|
* Returns the parent preferences node of this node or null if this is
|
|
* the root of the preferences tree.
|
|
*
|
|
* @exception IllegalStateException if this node has been removed
|
|
*/
|
|
public abstract Preferences parent();
|
|
|
|
// abstract methods (export)
|
|
|
|
/**
|
|
* Export this node, but not its descendants, as XML to the
|
|
* indicated output stream. The XML will be encoded using UTF-8
|
|
* and will use a specified document type:<br>
|
|
* <code><!DOCTYPE preferences SYSTEM "http://java.sun.com/dtd/preferences.dtd"></code><br>
|
|
* @param os the output stream to which the XML is sent
|
|
* @throws BackingStoreException if preference data cannot be read
|
|
* @throws IOException if an error occurs while writing the XML
|
|
* @throws IllegalStateException if this node or an ancestor has been removed
|
|
*/
|
|
public abstract void exportNode(OutputStream os)
|
|
throws BackingStoreException,
|
|
IOException;
|
|
|
|
/**
|
|
* Export this node and all its descendants as XML to the
|
|
* indicated output stream. The XML will be encoded using UTF-8
|
|
* and will use a specified document type:<br>
|
|
* <code><!DOCTYPE preferences SYSTEM "http://java.sun.com/dtd/preferences.dtd"></code><br>
|
|
* @param os the output stream to which the XML is sent
|
|
* @throws BackingStoreException if preference data cannot be read
|
|
* @throws IOException if an error occurs while writing the XML
|
|
* @throws IllegalStateException if this node or an ancestor has been removed
|
|
*/
|
|
public abstract void exportSubtree(OutputStream os)
|
|
throws BackingStoreException,
|
|
IOException;
|
|
|
|
// abstract methods (preference entry manipulation)
|
|
|
|
/**
|
|
* Returns an (possibly empty) array with all the keys of the preference
|
|
* entries of this node.
|
|
*
|
|
* @exception BackingStoreException when the backing store cannot be
|
|
* reached
|
|
* @exception IllegalStateException if this node has been removed
|
|
*/
|
|
public abstract String[] keys() throws BackingStoreException;
|
|
|
|
/**
|
|
* Returns the value associated with the key in this preferences node. If
|
|
* the default value of the key cannot be found in the preferences node
|
|
* entries or something goes wrong with the backing store the supplied
|
|
* default value is returned.
|
|
*
|
|
* @exception IllegalArgumentException if key is larger then 80 characters
|
|
* @exception IllegalStateException if this node has been removed
|
|
* @exception NullPointerException if key is null
|
|
*/
|
|
public abstract String get(String key, String defaultVal);
|
|
|
|
/**
|
|
* Convenience method for getting the given entry as a boolean.
|
|
* When the string representation of the requested entry is either
|
|
* "true" or "false" (ignoring case) then that value is returned,
|
|
* otherwise the given default boolean value is returned.
|
|
*
|
|
* @exception IllegalArgumentException if key is larger then 80 characters
|
|
* @exception IllegalStateException if this node has been removed
|
|
* @exception NullPointerException if key is null
|
|
*/
|
|
public abstract boolean getBoolean(String key, boolean defaultVal);
|
|
|
|
/**
|
|
* Convenience method for getting the given entry as a byte array.
|
|
* When the string representation of the requested entry is a valid
|
|
* Base64 encoded string (without any other characters, such as newlines)
|
|
* then the decoded Base64 string is returned as byte array,
|
|
* otherwise the given default byte array value is returned.
|
|
*
|
|
* @exception IllegalArgumentException if key is larger then 80 characters
|
|
* @exception IllegalStateException if this node has been removed
|
|
* @exception NullPointerException if key is null
|
|
*/
|
|
public abstract byte[] getByteArray(String key, byte[] defaultVal);
|
|
|
|
/**
|
|
* Convenience method for getting the given entry as a double.
|
|
* When the string representation of the requested entry can be decoded
|
|
* with <code>Double.parseDouble()</code> then that double is returned,
|
|
* otherwise the given default double value is returned.
|
|
*
|
|
* @exception IllegalArgumentException if key is larger then 80 characters
|
|
* @exception IllegalStateException if this node has been removed
|
|
* @exception NullPointerException if key is null
|
|
*/
|
|
public abstract double getDouble(String key, double defaultVal);
|
|
|
|
/**
|
|
* Convenience method for getting the given entry as a float.
|
|
* When the string representation of the requested entry can be decoded
|
|
* with <code>Float.parseFloat()</code> then that float is returned,
|
|
* otherwise the given default float value is returned.
|
|
*
|
|
* @exception IllegalArgumentException if key is larger then 80 characters
|
|
* @exception IllegalStateException if this node has been removed
|
|
* @exception NullPointerException if key is null
|
|
*/
|
|
public abstract float getFloat(String key, float defaultVal);
|
|
|
|
/**
|
|
* Convenience method for getting the given entry as an integer.
|
|
* When the string representation of the requested entry can be decoded
|
|
* with <code>Integer.parseInt()</code> then that integer is returned,
|
|
* otherwise the given default integer value is returned.
|
|
*
|
|
* @exception IllegalArgumentException if key is larger then 80 characters
|
|
* @exception IllegalStateException if this node has been removed
|
|
* @exception NullPointerException if key is null
|
|
*/
|
|
public abstract int getInt(String key, int defaultVal);
|
|
|
|
/**
|
|
* Convenience method for getting the given entry as a long.
|
|
* When the string representation of the requested entry can be decoded
|
|
* with <code>Long.parseLong()</code> then that long is returned,
|
|
* otherwise the given default long value is returned.
|
|
*
|
|
* @exception IllegalArgumentException if key is larger then 80 characters
|
|
* @exception IllegalStateException if this node has been removed
|
|
* @exception NullPointerException if key is null
|
|
*/
|
|
public abstract long getLong(String key, long defaultVal);
|
|
|
|
/**
|
|
* Sets the value of the given preferences entry for this node.
|
|
* Key and value cannot be null, the key cannot exceed 80 characters
|
|
* and the value cannot exceed 8192 characters.
|
|
* <p>
|
|
* The result will be immediatly visible in this VM, but may not be
|
|
* immediatly written to the backing store.
|
|
*
|
|
* @exception NullPointerException if either key or value are null
|
|
* @exception IllegalArgumentException if either key or value are to large
|
|
* @exception IllegalStateException when this node has been removed
|
|
*/
|
|
public abstract void put(String key, String value);
|
|
|
|
/**
|
|
* Convenience method for setting the given entry as a boolean.
|
|
* The boolean is converted with <code>Boolean.toString(value)</code>
|
|
* and then stored in the preference entry as that string.
|
|
*
|
|
* @exception NullPointerException if key is null
|
|
* @exception IllegalArgumentException if the key length is to large
|
|
* @exception IllegalStateException when this node has been removed
|
|
*/
|
|
public abstract void putBoolean(String key, boolean value);
|
|
|
|
/**
|
|
* 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
|
|
* @exception IllegalStateException when this node has been removed
|
|
*/
|
|
public abstract void putByteArray(String key, byte[] value);
|
|
|
|
/**
|
|
* 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
|
|
*/
|
|
public abstract 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
|
|
*/
|
|
public abstract 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
|
|
*/
|
|
public abstract 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
|
|
*/
|
|
public abstract 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
|
|
*/
|
|
public abstract 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
|
|
*/
|
|
public abstract 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
|
|
*/
|
|
public abstract 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
|
|
*/
|
|
public abstract 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
|
|
*/
|
|
public abstract void removeNode() throws BackingStoreException;
|
|
|
|
// abstract methods (listeners)
|
|
|
|
public abstract void addNodeChangeListener(NodeChangeListener listener);
|
|
|
|
public abstract void addPreferenceChangeListener
|
|
(PreferenceChangeListener listener);
|
|
|
|
public abstract void removeNodeChangeListener(NodeChangeListener listener);
|
|
|
|
public abstract void removePreferenceChangeListener
|
|
(PreferenceChangeListener listener);
|
|
}
|