| /* |
| * Copyright (C) 2014 The Android Open Source Project |
| * Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code 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 |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| package java.util.prefs; |
| |
| import java.util.*; |
| import java.io.*; |
| import java.security.AccessController; |
| import java.security.PrivilegedAction; |
| // These imports needed only as a workaround for a JavaDoc bug |
| import java.lang.Integer; |
| import java.lang.Long; |
| import java.lang.Float; |
| import java.lang.Double; |
| |
| /** |
| * This class provides a skeletal implementation of the {@link Preferences} |
| * class, greatly easing the task of implementing it. |
| * |
| * <p><strong>This class is for <tt>Preferences</tt> implementers only. |
| * Normal users of the <tt>Preferences</tt> facility should have no need to |
| * consult this documentation. The {@link Preferences} documentation |
| * should suffice.</strong> |
| * |
| * <p>Implementors must override the nine abstract service-provider interface |
| * (SPI) methods: {@link #getSpi(String)}, {@link #putSpi(String,String)}, |
| * {@link #removeSpi(String)}, {@link #childSpi(String)}, {@link |
| * #removeNodeSpi()}, {@link #keysSpi()}, {@link #childrenNamesSpi()}, {@link |
| * #syncSpi()} and {@link #flushSpi()}. All of the concrete methods specify |
| * precisely how they are implemented atop these SPI methods. The implementor |
| * may, at his discretion, override one or more of the concrete methods if the |
| * default implementation is unsatisfactory for any reason, such as |
| * performance. |
| * |
| * <p>The SPI methods fall into three groups concerning exception |
| * behavior. The <tt>getSpi</tt> method should never throw exceptions, but it |
| * doesn't really matter, as any exception thrown by this method will be |
| * intercepted by {@link #get(String,String)}, which will return the specified |
| * default value to the caller. The <tt>removeNodeSpi, keysSpi, |
| * childrenNamesSpi, syncSpi</tt> and <tt>flushSpi</tt> methods are specified |
| * to throw {@link BackingStoreException}, and the implementation is required |
| * to throw this checked exception if it is unable to perform the operation. |
| * The exception propagates outward, causing the corresponding API method |
| * to fail. |
| * |
| * <p>The remaining SPI methods {@link #putSpi(String,String)}, {@link |
| * #removeSpi(String)} and {@link #childSpi(String)} have more complicated |
| * exception behavior. They are not specified to throw |
| * <tt>BackingStoreException</tt>, as they can generally obey their contracts |
| * even if the backing store is unavailable. This is true because they return |
| * no information and their effects are not required to become permanent until |
| * a subsequent call to {@link Preferences#flush()} or |
| * {@link Preferences#sync()}. Generally speaking, these SPI methods should not |
| * throw exceptions. In some implementations, there may be circumstances |
| * under which these calls cannot even enqueue the requested operation for |
| * later processing. Even under these circumstances it is generally better to |
| * simply ignore the invocation and return, rather than throwing an |
| * exception. Under these circumstances, however, all subsequent invocations |
| * of <tt>flush()</tt> and <tt>sync</tt> should return <tt>false</tt>, as |
| * returning <tt>true</tt> would imply that all previous operations had |
| * successfully been made permanent. |
| * |
| * <p>There is one circumstance under which <tt>putSpi, removeSpi and |
| * childSpi</tt> <i>should</i> throw an exception: if the caller lacks |
| * sufficient privileges on the underlying operating system to perform the |
| * requested operation. This will, for instance, occur on most systems |
| * if a non-privileged user attempts to modify system preferences. |
| * (The required privileges will vary from implementation to |
| * implementation. On some implementations, they are the right to modify the |
| * contents of some directory in the file system; on others they are the right |
| * to modify contents of some key in a registry.) Under any of these |
| * circumstances, it would generally be undesirable to let the program |
| * continue executing as if these operations would become permanent at a later |
| * time. While implementations are not required to throw an exception under |
| * these circumstances, they are encouraged to do so. A {@link |
| * SecurityException} would be appropriate. |
| * |
| * <p>Most of the SPI methods require the implementation to read or write |
| * information at a preferences node. The implementor should beware of the |
| * fact that another VM may have concurrently deleted this node from the |
| * backing store. It is the implementation's responsibility to recreate the |
| * node if it has been deleted. |
| * |
| * <p>Implementation note: In Sun's default <tt>Preferences</tt> |
| * implementations, the user's identity is inherited from the underlying |
| * operating system and does not change for the lifetime of the virtual |
| * machine. It is recognized that server-side <tt>Preferences</tt> |
| * implementations may have the user identity change from request to request, |
| * implicitly passed to <tt>Preferences</tt> methods via the use of a |
| * static {@link ThreadLocal} instance. Authors of such implementations are |
| * <i>strongly</i> encouraged to determine the user at the time preferences |
| * are accessed (for example by the {@link #get(String,String)} or {@link |
| * #put(String,String)} method) rather than permanently associating a user |
| * with each <tt>Preferences</tt> instance. The latter behavior conflicts |
| * with normal <tt>Preferences</tt> usage and would lead to great confusion. |
| * |
| * @author Josh Bloch |
| * @see Preferences |
| * @since 1.4 |
| */ |
| public abstract class AbstractPreferences extends Preferences { |
| /** |
| * Our name relative to parent. |
| */ |
| private final String name; |
| |
| /** |
| * Our absolute path name. |
| */ |
| private final String absolutePath; |
| |
| /** |
| * Our parent node. |
| */ |
| final AbstractPreferences parent; |
| |
| /** |
| * Our root node. |
| */ |
| private final AbstractPreferences root; // Relative to this node |
| |
| /** |
| * This field should be <tt>true</tt> if this node did not exist in the |
| * backing store prior to the creation of this object. The field |
| * is initialized to false, but may be set to true by a subclass |
| * constructor (and should not be modified thereafter). This field |
| * indicates whether a node change event should be fired when |
| * creation is complete. |
| */ |
| protected boolean newNode = false; |
| |
| /** |
| * All known unremoved children of this node. (This "cache" is consulted |
| * prior to calling childSpi() or getChild(). |
| */ |
| private Map<String, AbstractPreferences> kidCache = new HashMap<>(); |
| |
| /** |
| * This field is used to keep track of whether or not this node has |
| * been removed. Once it's set to true, it will never be reset to false. |
| */ |
| private boolean removed = false; |
| |
| /** |
| * Registered preference change listeners. |
| */ |
| // Android-changed: Copy-on-read List of listeners, not copy-on-write array. |
| // It's not clear if this change provides overall benefit; it might be |
| // reverted in future. Discussion: http://b/111195881 |
| // private PreferenceChangeListener[] prefListeners = |
| // new PreferenceChangeListener[0]; |
| private final ArrayList<PreferenceChangeListener> prefListeners = new ArrayList<>(); |
| |
| /** |
| * Registered node change listeners. |
| */ |
| // Android-changed: Copy-on-read List of listeners, not copy-on-write array. |
| // private NodeChangeListener[] nodeListeners = new NodeChangeListener[0]; |
| private final ArrayList<NodeChangeListener> nodeListeners = new ArrayList<>(); |
| |
| /** |
| * An object whose monitor is used to lock this node. This object |
| * is used in preference to the node itself to reduce the likelihood of |
| * intentional or unintentional denial of service due to a locked node. |
| * To avoid deadlock, a node is <i>never</i> locked by a thread that |
| * holds a lock on a descendant of that node. |
| */ |
| protected final Object lock = new Object(); |
| |
| /** |
| * Creates a preference node with the specified parent and the specified |
| * name relative to its parent. |
| * |
| * @param parent the parent of this preference node, or null if this |
| * is the root. |
| * @param name the name of this preference node, relative to its parent, |
| * or <tt>""</tt> if this is the root. |
| * @throws IllegalArgumentException if <tt>name</tt> contains a slash |
| * (<tt>'/'</tt>), or <tt>parent</tt> is <tt>null</tt> and |
| * name isn't <tt>""</tt>. |
| */ |
| protected AbstractPreferences(AbstractPreferences parent, String name) { |
| if (parent==null) { |
| if (!name.equals("")) |
| throw new IllegalArgumentException("Root name '"+name+ |
| "' must be \"\""); |
| this.absolutePath = "/"; |
| root = this; |
| } else { |
| if (name.indexOf('/') != -1) |
| throw new IllegalArgumentException("Name '" + name + |
| "' contains '/'"); |
| if (name.equals("")) |
| throw new IllegalArgumentException("Illegal name: empty string"); |
| |
| root = parent.root; |
| absolutePath = (parent==root ? "/" + name |
| : parent.absolutePath() + "/" + name); |
| } |
| this.name = name; |
| this.parent = parent; |
| } |
| |
| /** |
| * Implements the <tt>put</tt> method as per the specification in |
| * {@link Preferences#put(String,String)}. |
| * |
| * <p>This implementation checks that the key and value are legal, |
| * obtains this preference node's lock, checks that the node |
| * has not been removed, invokes {@link #putSpi(String,String)}, and if |
| * there are any preference change listeners, enqueues a notification |
| * event for processing by the event dispatch thread. |
| * |
| * @param key key with which the specified value is to be associated. |
| * @param value value to be associated with the specified key. |
| * @throws NullPointerException if key or value is <tt>null</tt>. |
| * @throws IllegalArgumentException if <tt>key.length()</tt> exceeds |
| * <tt>MAX_KEY_LENGTH</tt> or if <tt>value.length</tt> exceeds |
| * <tt>MAX_VALUE_LENGTH</tt>. |
| * @throws IllegalStateException if this node (or an ancestor) has been |
| * removed with the {@link #removeNode()} method. |
| */ |
| public void put(String key, String value) { |
| if (key==null || value==null) |
| throw new NullPointerException(); |
| if (key.length() > MAX_KEY_LENGTH) |
| throw new IllegalArgumentException("Key too long: "+key); |
| if (value.length() > MAX_VALUE_LENGTH) |
| throw new IllegalArgumentException("Value too long: "+value); |
| |
| synchronized(lock) { |
| if (removed) |
| throw new IllegalStateException("Node has been removed."); |
| |
| putSpi(key, value); |
| enqueuePreferenceChangeEvent(key, value); |
| } |
| } |
| |
| /** |
| * Implements the <tt>get</tt> method as per the specification in |
| * {@link Preferences#get(String,String)}. |
| * |
| * <p>This implementation first checks to see if <tt>key</tt> is |
| * <tt>null</tt> throwing a <tt>NullPointerException</tt> if this is |
| * the case. Then it obtains this preference node's lock, |
| * checks that the node has not been removed, invokes {@link |
| * #getSpi(String)}, and returns the result, unless the <tt>getSpi</tt> |
| * invocation returns <tt>null</tt> or throws an exception, in which case |
| * this invocation returns <tt>def</tt>. |
| * |
| * @param key key whose associated value is to be returned. |
| * @param def the value to be returned in the event that this |
| * preference node has no value associated with <tt>key</tt>. |
| * @return the value associated with <tt>key</tt>, or <tt>def</tt> |
| * if no value is associated with <tt>key</tt>. |
| * @throws IllegalStateException if this node (or an ancestor) has been |
| * removed with the {@link #removeNode()} method. |
| * @throws NullPointerException if key is <tt>null</tt>. (A |
| * <tt>null</tt> default <i>is</i> permitted.) |
| */ |
| public String get(String key, String def) { |
| if (key==null) |
| throw new NullPointerException("Null key"); |
| synchronized(lock) { |
| if (removed) |
| throw new IllegalStateException("Node has been removed."); |
| |
| String result = null; |
| try { |
| result = getSpi(key); |
| } catch (Exception e) { |
| // Ignoring exception causes default to be returned |
| } |
| return (result==null ? def : result); |
| } |
| } |
| |
| /** |
| * Implements the <tt>remove(String)</tt> method as per the specification |
| * in {@link Preferences#remove(String)}. |
| * |
| * <p>This implementation obtains this preference node's lock, |
| * checks that the node has not been removed, invokes |
| * {@link #removeSpi(String)} and if there are any preference |
| * change listeners, enqueues a notification event for processing by the |
| * event dispatch thread. |
| * |
| * @param key key whose mapping is to be removed from the preference node. |
| * @throws IllegalStateException if this node (or an ancestor) has been |
| * removed with the {@link #removeNode()} method. |
| * @throws NullPointerException {@inheritDoc}. |
| */ |
| public void remove(String key) { |
| Objects.requireNonNull(key, "Specified key cannot be null"); |
| synchronized(lock) { |
| if (removed) |
| throw new IllegalStateException("Node has been removed."); |
| |
| removeSpi(key); |
| enqueuePreferenceChangeEvent(key, null); |
| } |
| } |
| |
| /** |
| * Implements the <tt>clear</tt> method as per the specification in |
| * {@link Preferences#clear()}. |
| * |
| * <p>This implementation obtains this preference node's lock, |
| * invokes {@link #keys()} to obtain an array of keys, and |
| * iterates over the array invoking {@link #remove(String)} on each key. |
| * |
| * @throws BackingStoreException if this operation cannot be completed |
| * due to a failure in the backing store, or inability to |
| * communicate with it. |
| * @throws IllegalStateException if this node (or an ancestor) has been |
| * removed with the {@link #removeNode()} method. |
| */ |
| public void clear() throws BackingStoreException { |
| synchronized(lock) { |
| String[] keys = keys(); |
| for (int i=0; i<keys.length; i++) |
| remove(keys[i]); |
| } |
| } |
| |
| /** |
| * Implements the <tt>putInt</tt> method as per the specification in |
| * {@link Preferences#putInt(String,int)}. |
| * |
| * <p>This implementation translates <tt>value</tt> to a string with |
| * {@link Integer#toString(int)} and invokes {@link #put(String,String)} |
| * on the result. |
| * |
| * @param key key with which the string form of value is to be associated. |
| * @param value value whose string form is to be associated with key. |
| * @throws NullPointerException if key is <tt>null</tt>. |
| * @throws IllegalArgumentException if <tt>key.length()</tt> exceeds |
| * <tt>MAX_KEY_LENGTH</tt>. |
| * @throws IllegalStateException if this node (or an ancestor) has been |
| * removed with the {@link #removeNode()} method. |
| */ |
| public void putInt(String key, int value) { |
| put(key, Integer.toString(value)); |
| } |
| |
| /** |
| * Implements the <tt>getInt</tt> method as per the specification in |
| * {@link Preferences#getInt(String,int)}. |
| * |
| * <p>This implementation invokes {@link #get(String,String) <tt>get(key, |
| * null)</tt>}. If the return value is non-null, the implementation |
| * attempts to translate it to an <tt>int</tt> with |
| * {@link Integer#parseInt(String)}. If the attempt succeeds, the return |
| * value is returned by this method. Otherwise, <tt>def</tt> is returned. |
| * |
| * @param key key whose associated value is to be returned as an int. |
| * @param def the value to be returned in the event that this |
| * preference node has no value associated with <tt>key</tt> |
| * or the associated value cannot be interpreted as an int. |
| * @return the int value represented by the string associated with |
| * <tt>key</tt> in this preference node, or <tt>def</tt> if the |
| * associated value does not exist or cannot be interpreted as |
| * an int. |
| * @throws IllegalStateException if this node (or an ancestor) has been |
| * removed with the {@link #removeNode()} method. |
| * @throws NullPointerException if <tt>key</tt> is <tt>null</tt>. |
| */ |
| public int getInt(String key, int def) { |
| int result = def; |
| try { |
| String value = get(key, null); |
| if (value != null) |
| result = Integer.parseInt(value); |
| } catch (NumberFormatException e) { |
| // Ignoring exception causes specified default to be returned |
| } |
| |
| return result; |
| } |
| |
| /** |
| * Implements the <tt>putLong</tt> method as per the specification in |
| * {@link Preferences#putLong(String,long)}. |
| * |
| * <p>This implementation translates <tt>value</tt> to a string with |
| * {@link Long#toString(long)} and invokes {@link #put(String,String)} |
| * on the result. |
| * |
| * @param key key with which the string form of value is to be associated. |
| * @param value value whose string form is to be associated with key. |
| * @throws NullPointerException if key is <tt>null</tt>. |
| * @throws IllegalArgumentException if <tt>key.length()</tt> exceeds |
| * <tt>MAX_KEY_LENGTH</tt>. |
| * @throws IllegalStateException if this node (or an ancestor) has been |
| * removed with the {@link #removeNode()} method. |
| */ |
| public void putLong(String key, long value) { |
| put(key, Long.toString(value)); |
| } |
| |
| /** |
| * Implements the <tt>getLong</tt> method as per the specification in |
| * {@link Preferences#getLong(String,long)}. |
| * |
| * <p>This implementation invokes {@link #get(String,String) <tt>get(key, |
| * null)</tt>}. If the return value is non-null, the implementation |
| * attempts to translate it to a <tt>long</tt> with |
| * {@link Long#parseLong(String)}. If the attempt succeeds, the return |
| * value is returned by this method. Otherwise, <tt>def</tt> is returned. |
| * |
| * @param key key whose associated value is to be returned as a long. |
| * @param def the value to be returned in the event that this |
| * preference node has no value associated with <tt>key</tt> |
| * or the associated value cannot be interpreted as a long. |
| * @return the long value represented by the string associated with |
| * <tt>key</tt> in this preference node, or <tt>def</tt> if the |
| * associated value does not exist or cannot be interpreted as |
| * a long. |
| * @throws IllegalStateException if this node (or an ancestor) has been |
| * removed with the {@link #removeNode()} method. |
| * @throws NullPointerException if <tt>key</tt> is <tt>null</tt>. |
| */ |
| public long getLong(String key, long def) { |
| long result = def; |
| try { |
| String value = get(key, null); |
| if (value != null) |
| result = Long.parseLong(value); |
| } catch (NumberFormatException e) { |
| // Ignoring exception causes specified default to be returned |
| } |
| |
| return result; |
| } |
| |
| /** |
| * Implements the <tt>putBoolean</tt> method as per the specification in |
| * {@link Preferences#putBoolean(String,boolean)}. |
| * |
| * <p>This implementation translates <tt>value</tt> to a string with |
| * {@link String#valueOf(boolean)} and invokes {@link #put(String,String)} |
| * on the result. |
| * |
| * @param key key with which the string form of value is to be associated. |
| * @param value value whose string form is to be associated with key. |
| * @throws NullPointerException if key is <tt>null</tt>. |
| * @throws IllegalArgumentException if <tt>key.length()</tt> exceeds |
| * <tt>MAX_KEY_LENGTH</tt>. |
| * @throws IllegalStateException if this node (or an ancestor) has been |
| * removed with the {@link #removeNode()} method. |
| */ |
| public void putBoolean(String key, boolean value) { |
| put(key, String.valueOf(value)); |
| } |
| |
| /** |
| * Implements the <tt>getBoolean</tt> method as per the specification in |
| * {@link Preferences#getBoolean(String,boolean)}. |
| * |
| * <p>This implementation invokes {@link #get(String,String) <tt>get(key, |
| * null)</tt>}. If the return value is non-null, it is compared with |
| * <tt>"true"</tt> using {@link String#equalsIgnoreCase(String)}. If the |
| * comparison returns <tt>true</tt>, this invocation returns |
| * <tt>true</tt>. Otherwise, the original return value is compared with |
| * <tt>"false"</tt>, again using {@link String#equalsIgnoreCase(String)}. |
| * If the comparison returns <tt>true</tt>, this invocation returns |
| * <tt>false</tt>. Otherwise, this invocation returns <tt>def</tt>. |
| * |
| * @param key key whose associated value is to be returned as a boolean. |
| * @param def the value to be returned in the event that this |
| * preference node has no value associated with <tt>key</tt> |
| * or the associated value cannot be interpreted as a boolean. |
| * @return the boolean value represented by the string associated with |
| * <tt>key</tt> in this preference node, or <tt>def</tt> if the |
| * associated value does not exist or cannot be interpreted as |
| * a boolean. |
| * @throws IllegalStateException if this node (or an ancestor) has been |
| * removed with the {@link #removeNode()} method. |
| * @throws NullPointerException if <tt>key</tt> is <tt>null</tt>. |
| */ |
| public boolean getBoolean(String key, boolean def) { |
| boolean result = def; |
| String value = get(key, null); |
| if (value != null) { |
| if (value.equalsIgnoreCase("true")) |
| result = true; |
| else if (value.equalsIgnoreCase("false")) |
| result = false; |
| } |
| |
| return result; |
| } |
| |
| /** |
| * Implements the <tt>putFloat</tt> method as per the specification in |
| * {@link Preferences#putFloat(String,float)}. |
| * |
| * <p>This implementation translates <tt>value</tt> to a string with |
| * {@link Float#toString(float)} and invokes {@link #put(String,String)} |
| * on the result. |
| * |
| * @param key key with which the string form of value is to be associated. |
| * @param value value whose string form is to be associated with key. |
| * @throws NullPointerException if key is <tt>null</tt>. |
| * @throws IllegalArgumentException if <tt>key.length()</tt> exceeds |
| * <tt>MAX_KEY_LENGTH</tt>. |
| * @throws IllegalStateException if this node (or an ancestor) has been |
| * removed with the {@link #removeNode()} method. |
| */ |
| public void putFloat(String key, float value) { |
| put(key, Float.toString(value)); |
| } |
| |
| /** |
| * Implements the <tt>getFloat</tt> method as per the specification in |
| * {@link Preferences#getFloat(String,float)}. |
| * |
| * <p>This implementation invokes {@link #get(String,String) <tt>get(key, |
| * null)</tt>}. If the return value is non-null, the implementation |
| * attempts to translate it to an <tt>float</tt> with |
| * {@link Float#parseFloat(String)}. If the attempt succeeds, the return |
| * value is returned by this method. Otherwise, <tt>def</tt> is returned. |
| * |
| * @param key key whose associated value is to be returned as a float. |
| * @param def the value to be returned in the event that this |
| * preference node has no value associated with <tt>key</tt> |
| * or the associated value cannot be interpreted as a float. |
| * @return the float value represented by the string associated with |
| * <tt>key</tt> in this preference node, or <tt>def</tt> if the |
| * associated value does not exist or cannot be interpreted as |
| * a float. |
| * @throws IllegalStateException if this node (or an ancestor) has been |
| * removed with the {@link #removeNode()} method. |
| * @throws NullPointerException if <tt>key</tt> is <tt>null</tt>. |
| */ |
| public float getFloat(String key, float def) { |
| float result = def; |
| try { |
| String value = get(key, null); |
| if (value != null) |
| result = Float.parseFloat(value); |
| } catch (NumberFormatException e) { |
| // Ignoring exception causes specified default to be returned |
| } |
| |
| return result; |
| } |
| |
| /** |
| * Implements the <tt>putDouble</tt> method as per the specification in |
| * {@link Preferences#putDouble(String,double)}. |
| * |
| * <p>This implementation translates <tt>value</tt> to a string with |
| * {@link Double#toString(double)} and invokes {@link #put(String,String)} |
| * on the result. |
| * |
| * @param key key with which the string form of value is to be associated. |
| * @param value value whose string form is to be associated with key. |
| * @throws NullPointerException if key is <tt>null</tt>. |
| * @throws IllegalArgumentException if <tt>key.length()</tt> exceeds |
| * <tt>MAX_KEY_LENGTH</tt>. |
| * @throws IllegalStateException if this node (or an ancestor) has been |
| * removed with the {@link #removeNode()} method. |
| */ |
| public void putDouble(String key, double value) { |
| put(key, Double.toString(value)); |
| } |
| |
| /** |
| * Implements the <tt>getDouble</tt> method as per the specification in |
| * {@link Preferences#getDouble(String,double)}. |
| * |
| * <p>This implementation invokes {@link #get(String,String) <tt>get(key, |
| * null)</tt>}. If the return value is non-null, the implementation |
| * attempts to translate it to an <tt>double</tt> with |
| * {@link Double#parseDouble(String)}. If the attempt succeeds, the return |
| * value is returned by this method. Otherwise, <tt>def</tt> is returned. |
| * |
| * @param key key whose associated value is to be returned as a double. |
| * @param def the value to be returned in the event that this |
| * preference node has no value associated with <tt>key</tt> |
| * or the associated value cannot be interpreted as a double. |
| * @return the double value represented by the string associated with |
| * <tt>key</tt> in this preference node, or <tt>def</tt> if the |
| * associated value does not exist or cannot be interpreted as |
| * a double. |
| * @throws IllegalStateException if this node (or an ancestor) has been |
| * removed with the {@link #removeNode()} method. |
| * @throws NullPointerException if <tt>key</tt> is <tt>null</tt>. |
| */ |
| public double getDouble(String key, double def) { |
| double result = def; |
| try { |
| String value = get(key, null); |
| if (value != null) |
| result = Double.parseDouble(value); |
| } catch (NumberFormatException e) { |
| // Ignoring exception causes specified default to be returned |
| } |
| |
| return result; |
| } |
| |
| /** |
| * Implements the <tt>putByteArray</tt> method as per the specification in |
| * {@link Preferences#putByteArray(String,byte[])}. |
| * |
| * @param key key with which the string form of value is to be associated. |
| * @param value value whose string form is to be associated with key. |
| * @throws NullPointerException if key or value is <tt>null</tt>. |
| * @throws IllegalArgumentException if key.length() exceeds MAX_KEY_LENGTH |
| * or if value.length exceeds MAX_VALUE_LENGTH*3/4. |
| * @throws IllegalStateException if this node (or an ancestor) has been |
| * removed with the {@link #removeNode()} method. |
| */ |
| public void putByteArray(String key, byte[] value) { |
| put(key, Base64.byteArrayToBase64(value)); |
| } |
| |
| /** |
| * Implements the <tt>getByteArray</tt> method as per the specification in |
| * {@link Preferences#getByteArray(String,byte[])}. |
| * |
| * @param key key whose associated value is to be returned as a byte array. |
| * @param def the value to be returned in the event that this |
| * preference node has no value associated with <tt>key</tt> |
| * or the associated value cannot be interpreted as a byte array. |
| * @return the byte array value represented by the string associated with |
| * <tt>key</tt> in this preference node, or <tt>def</tt> if the |
| * associated value does not exist or cannot be interpreted as |
| * a byte array. |
| * @throws IllegalStateException if this node (or an ancestor) has been |
| * removed with the {@link #removeNode()} method. |
| * @throws NullPointerException if <tt>key</tt> is <tt>null</tt>. (A |
| * <tt>null</tt> value for <tt>def</tt> <i>is</i> permitted.) |
| */ |
| public byte[] getByteArray(String key, byte[] def) { |
| byte[] result = def; |
| String value = get(key, null); |
| try { |
| if (value != null) |
| result = Base64.base64ToByteArray(value); |
| } |
| catch (RuntimeException e) { |
| // Ignoring exception causes specified default to be returned |
| } |
| |
| return result; |
| } |
| |
| /** |
| * Implements the <tt>keys</tt> method as per the specification in |
| * {@link Preferences#keys()}. |
| * |
| * <p>This implementation obtains this preference node's lock, checks that |
| * the node has not been removed and invokes {@link #keysSpi()}. |
| * |
| * @return an array of the keys that have an associated value in this |
| * preference node. |
| * @throws BackingStoreException if this operation cannot be completed |
| * due to a failure in the backing store, or inability to |
| * communicate with it. |
| * @throws IllegalStateException if this node (or an ancestor) has been |
| * removed with the {@link #removeNode()} method. |
| */ |
| public String[] keys() throws BackingStoreException { |
| synchronized(lock) { |
| if (removed) |
| throw new IllegalStateException("Node has been removed."); |
| |
| return keysSpi(); |
| } |
| } |
| |
| /** |
| * Implements the <tt>children</tt> method as per the specification in |
| * {@link Preferences#childrenNames()}. |
| * |
| * <p>This implementation obtains this preference node's lock, checks that |
| * the node has not been removed, constructs a <tt>TreeSet</tt> initialized |
| * to the names of children already cached (the children in this node's |
| * "child-cache"), invokes {@link #childrenNamesSpi()}, and adds all of the |
| * returned child-names into the set. The elements of the tree set are |
| * dumped into a <tt>String</tt> array using the <tt>toArray</tt> method, |
| * and this array is returned. |
| * |
| * @return the names of the children of this preference node. |
| * @throws BackingStoreException if this operation cannot be completed |
| * due to a failure in the backing store, or inability to |
| * communicate with it. |
| * @throws IllegalStateException if this node (or an ancestor) has been |
| * removed with the {@link #removeNode()} method. |
| * @see #cachedChildren() |
| */ |
| public String[] childrenNames() throws BackingStoreException { |
| synchronized(lock) { |
| if (removed) |
| throw new IllegalStateException("Node has been removed."); |
| |
| Set<String> s = new TreeSet<>(kidCache.keySet()); |
| for (String kid : childrenNamesSpi()) |
| s.add(kid); |
| return s.toArray(EMPTY_STRING_ARRAY); |
| } |
| } |
| |
| private static final String[] EMPTY_STRING_ARRAY = new String[0]; |
| |
| /** |
| * Returns all known unremoved children of this node. |
| * |
| * @return all known unremoved children of this node. |
| */ |
| protected final AbstractPreferences[] cachedChildren() { |
| return kidCache.values().toArray(EMPTY_ABSTRACT_PREFS_ARRAY); |
| } |
| |
| private static final AbstractPreferences[] EMPTY_ABSTRACT_PREFS_ARRAY |
| = new AbstractPreferences[0]; |
| |
| /** |
| * Implements the <tt>parent</tt> method as per the specification in |
| * {@link Preferences#parent()}. |
| * |
| * <p>This implementation obtains this preference node's lock, checks that |
| * the node has not been removed and returns the parent value that was |
| * passed to this node's constructor. |
| * |
| * @return the parent of this preference node. |
| * @throws IllegalStateException if this node (or an ancestor) has been |
| * removed with the {@link #removeNode()} method. |
| */ |
| public Preferences parent() { |
| synchronized(lock) { |
| if (removed) |
| throw new IllegalStateException("Node has been removed."); |
| |
| return parent; |
| } |
| } |
| |
| /** |
| * Implements the <tt>node</tt> method as per the specification in |
| * {@link Preferences#node(String)}. |
| * |
| * <p>This implementation obtains this preference node's lock and checks |
| * that the node has not been removed. If <tt>path</tt> is <tt>""</tt>, |
| * this node is returned; if <tt>path</tt> is <tt>"/"</tt>, this node's |
| * root is returned. If the first character in <tt>path</tt> is |
| * not <tt>'/'</tt>, the implementation breaks <tt>path</tt> into |
| * tokens and recursively traverses the path from this node to the |
| * named node, "consuming" a name and a slash from <tt>path</tt> at |
| * each step of the traversal. At each step, the current node is locked |
| * and the node's child-cache is checked for the named node. If it is |
| * not found, the name is checked to make sure its length does not |
| * exceed <tt>MAX_NAME_LENGTH</tt>. Then the {@link #childSpi(String)} |
| * method is invoked, and the result stored in this node's child-cache. |
| * If the newly created <tt>Preferences</tt> object's {@link #newNode} |
| * field is <tt>true</tt> and there are any node change listeners, |
| * a notification event is enqueued for processing by the event dispatch |
| * thread. |
| * |
| * <p>When there are no more tokens, the last value found in the |
| * child-cache or returned by <tt>childSpi</tt> is returned by this |
| * method. If during the traversal, two <tt>"/"</tt> tokens occur |
| * consecutively, or the final token is <tt>"/"</tt> (rather than a name), |
| * an appropriate <tt>IllegalArgumentException</tt> is thrown. |
| * |
| * <p> If the first character of <tt>path</tt> is <tt>'/'</tt> |
| * (indicating an absolute path name) this preference node's |
| * lock is dropped prior to breaking <tt>path</tt> into tokens, and |
| * this method recursively traverses the path starting from the root |
| * (rather than starting from this node). The traversal is otherwise |
| * identical to the one described for relative path names. Dropping |
| * the lock on this node prior to commencing the traversal at the root |
| * node is essential to avoid the possibility of deadlock, as per the |
| * {@link #lock locking invariant}. |
| * |
| * @param path the path name of the preference node to return. |
| * @return the specified preference node. |
| * @throws IllegalArgumentException if the path name is invalid (i.e., |
| * it contains multiple consecutive slash characters, or ends |
| * with a slash character and is more than one character long). |
| * @throws IllegalStateException if this node (or an ancestor) has been |
| * removed with the {@link #removeNode()} method. |
| */ |
| public Preferences node(String path) { |
| synchronized(lock) { |
| if (removed) |
| throw new IllegalStateException("Node has been removed."); |
| if (path.equals("")) |
| return this; |
| if (path.equals("/")) |
| return root; |
| if (path.charAt(0) != '/') |
| return node(new StringTokenizer(path, "/", true)); |
| } |
| |
| // Absolute path. Note that we've dropped our lock to avoid deadlock |
| return root.node(new StringTokenizer(path.substring(1), "/", true)); |
| } |
| |
| /** |
| * tokenizer contains <name> {'/' <name>}* |
| */ |
| private Preferences node(StringTokenizer path) { |
| String token = path.nextToken(); |
| if (token.equals("/")) // Check for consecutive slashes |
| throw new IllegalArgumentException("Consecutive slashes in path"); |
| synchronized(lock) { |
| AbstractPreferences child = kidCache.get(token); |
| if (child == null) { |
| if (token.length() > MAX_NAME_LENGTH) |
| throw new IllegalArgumentException( |
| "Node name " + token + " too long"); |
| child = childSpi(token); |
| if (child.newNode) |
| enqueueNodeAddedEvent(child); |
| kidCache.put(token, child); |
| } |
| if (!path.hasMoreTokens()) |
| return child; |
| path.nextToken(); // Consume slash |
| if (!path.hasMoreTokens()) |
| throw new IllegalArgumentException("Path ends with slash"); |
| return child.node(path); |
| } |
| } |
| |
| /** |
| * Implements the <tt>nodeExists</tt> method as per the specification in |
| * {@link Preferences#nodeExists(String)}. |
| * |
| * <p>This implementation is very similar to {@link #node(String)}, |
| * except that {@link #getChild(String)} is used instead of {@link |
| * #childSpi(String)}. |
| * |
| * @param path the path name of the node whose existence is to be checked. |
| * @return true if the specified node exists. |
| * @throws BackingStoreException if this operation cannot be completed |
| * due to a failure in the backing store, or inability to |
| * communicate with it. |
| * @throws IllegalArgumentException if the path name is invalid (i.e., |
| * it contains multiple consecutive slash characters, or ends |
| * with a slash character and is more than one character long). |
| * @throws IllegalStateException if this node (or an ancestor) has been |
| * removed with the {@link #removeNode()} method and |
| * <tt>pathname</tt> is not the empty string (<tt>""</tt>). |
| */ |
| public boolean nodeExists(String path) |
| throws BackingStoreException |
| { |
| synchronized(lock) { |
| if (path.equals("")) |
| return !removed; |
| if (removed) |
| throw new IllegalStateException("Node has been removed."); |
| if (path.equals("/")) |
| return true; |
| if (path.charAt(0) != '/') |
| return nodeExists(new StringTokenizer(path, "/", true)); |
| } |
| |
| // Absolute path. Note that we've dropped our lock to avoid deadlock |
| return root.nodeExists(new StringTokenizer(path.substring(1), "/", |
| true)); |
| } |
| |
| /** |
| * tokenizer contains <name> {'/' <name>}* |
| */ |
| private boolean nodeExists(StringTokenizer path) |
| throws BackingStoreException |
| { |
| String token = path.nextToken(); |
| if (token.equals("/")) // Check for consecutive slashes |
| throw new IllegalArgumentException("Consecutive slashes in path"); |
| synchronized(lock) { |
| AbstractPreferences child = kidCache.get(token); |
| if (child == null) |
| child = getChild(token); |
| if (child==null) |
| return false; |
| if (!path.hasMoreTokens()) |
| return true; |
| path.nextToken(); // Consume slash |
| if (!path.hasMoreTokens()) |
| throw new IllegalArgumentException("Path ends with slash"); |
| return child.nodeExists(path); |
| } |
| } |
| |
| /** |
| |
| * Implements the <tt>removeNode()</tt> method as per the specification in |
| * {@link Preferences#removeNode()}. |
| * |
| * <p>This implementation checks to see that this node is the root; if so, |
| * it throws an appropriate exception. Then, it locks this node's parent, |
| * and calls a recursive helper method that traverses the subtree rooted at |
| * this node. The recursive method locks the node on which it was called, |
| * checks that it has not already been removed, and then ensures that all |
| * of its children are cached: The {@link #childrenNamesSpi()} method is |
| * invoked and each returned child name is checked for containment in the |
| * child-cache. If a child is not already cached, the {@link |
| * #childSpi(String)} method is invoked to create a <tt>Preferences</tt> |
| * instance for it, and this instance is put into the child-cache. Then |
| * the helper method calls itself recursively on each node contained in its |
| * child-cache. Next, it invokes {@link #removeNodeSpi()}, marks itself |
| * as removed, and removes itself from its parent's child-cache. Finally, |
| * if there are any node change listeners, it enqueues a notification |
| * event for processing by the event dispatch thread. |
| * |
| * <p>Note that the helper method is always invoked with all ancestors up |
| * to the "closest non-removed ancestor" locked. |
| * |
| * @throws IllegalStateException if this node (or an ancestor) has already |
| * been removed with the {@link #removeNode()} method. |
| * @throws UnsupportedOperationException if this method is invoked on |
| * the root node. |
| * @throws BackingStoreException if this operation cannot be completed |
| * due to a failure in the backing store, or inability to |
| * communicate with it. |
| */ |
| public void removeNode() throws BackingStoreException { |
| if (this==root) |
| throw new UnsupportedOperationException("Can't remove the root!"); |
| synchronized(parent.lock) { |
| removeNode2(); |
| parent.kidCache.remove(name); |
| } |
| } |
| |
| /* |
| * Called with locks on all nodes on path from parent of "removal root" |
| * to this (including the former but excluding the latter). |
| */ |
| private void removeNode2() throws BackingStoreException { |
| synchronized(lock) { |
| if (removed) |
| throw new IllegalStateException("Node already removed."); |
| |
| // Ensure that all children are cached |
| String[] kidNames = childrenNamesSpi(); |
| for (int i=0; i<kidNames.length; i++) |
| if (!kidCache.containsKey(kidNames[i])) |
| kidCache.put(kidNames[i], childSpi(kidNames[i])); |
| |
| // Recursively remove all cached children |
| for (Iterator<AbstractPreferences> i = kidCache.values().iterator(); |
| i.hasNext();) { |
| try { |
| i.next().removeNode2(); |
| i.remove(); |
| } catch (BackingStoreException x) { } |
| } |
| |
| // Now we have no descendants - it's time to die! |
| removeNodeSpi(); |
| removed = true; |
| parent.enqueueNodeRemovedEvent(this); |
| } |
| } |
| |
| /** |
| * Implements the <tt>name</tt> method as per the specification in |
| * {@link Preferences#name()}. |
| * |
| * <p>This implementation merely returns the name that was |
| * passed to this node's constructor. |
| * |
| * @return this preference node's name, relative to its parent. |
| */ |
| public String name() { |
| return name; |
| } |
| |
| /** |
| * Implements the <tt>absolutePath</tt> method as per the specification in |
| * {@link Preferences#absolutePath()}. |
| * |
| * <p>This implementation merely returns the absolute path name that |
| * was computed at the time that this node was constructed (based on |
| * the name that was passed to this node's constructor, and the names |
| * that were passed to this node's ancestors' constructors). |
| * |
| * @return this preference node's absolute path name. |
| */ |
| public String absolutePath() { |
| return absolutePath; |
| } |
| |
| /** |
| * Implements the <tt>isUserNode</tt> method as per the specification in |
| * {@link Preferences#isUserNode()}. |
| * |
| * <p>This implementation compares this node's root node (which is stored |
| * in a private field) with the value returned by |
| * {@link Preferences#userRoot()}. If the two object references are |
| * identical, this method returns true. |
| * |
| * @return <tt>true</tt> if this preference node is in the user |
| * preference tree, <tt>false</tt> if it's in the system |
| * preference tree. |
| */ |
| public boolean isUserNode() { |
| return AccessController.doPrivileged( |
| new PrivilegedAction<Boolean>() { |
| public Boolean run() { |
| return root == Preferences.userRoot(); |
| } |
| }).booleanValue(); |
| } |
| |
| public void addPreferenceChangeListener(PreferenceChangeListener pcl) { |
| if (pcl==null) |
| throw new NullPointerException("Change listener is null."); |
| synchronized(lock) { |
| if (removed) |
| throw new IllegalStateException("Node has been removed."); |
| |
| // Android-changed: Copy-on-read List of listeners, not copy-on-write array. |
| /* |
| // Copy-on-write |
| PreferenceChangeListener[] old = prefListeners; |
| prefListeners = new PreferenceChangeListener[old.length + 1]; |
| System.arraycopy(old, 0, prefListeners, 0, old.length); |
| prefListeners[old.length] = pcl; |
| */ |
| prefListeners.add(pcl); |
| } |
| startEventDispatchThreadIfNecessary(); |
| } |
| |
| public void removePreferenceChangeListener(PreferenceChangeListener pcl) { |
| synchronized(lock) { |
| if (removed) |
| throw new IllegalStateException("Node has been removed."); |
| // Android-changed: Copy-on-read List of listeners, not copy-on-write array. |
| // if ((prefListeners == null) || (prefListeners.length == 0)) |
| if (!prefListeners.contains(pcl)) { |
| throw new IllegalArgumentException("Listener not registered."); |
| } |
| |
| // Android-changed: Copy-on-read List of listeners, not copy-on-write array. |
| /* |
| // Copy-on-write |
| PreferenceChangeListener[] newPl = |
| new PreferenceChangeListener[prefListeners.length - 1]; |
| int i = 0; |
| while (i < newPl.length && prefListeners[i] != pcl) |
| newPl[i] = prefListeners[i++]; |
| |
| if (i == newPl.length && prefListeners[i] != pcl) |
| throw new IllegalArgumentException("Listener not registered."); |
| while (i < newPl.length) |
| newPl[i] = prefListeners[++i]; |
| prefListeners = newPl; |
| */ |
| prefListeners.remove(pcl); |
| } |
| } |
| |
| public void addNodeChangeListener(NodeChangeListener ncl) { |
| if (ncl==null) |
| throw new NullPointerException("Change listener is null."); |
| synchronized(lock) { |
| if (removed) |
| throw new IllegalStateException("Node has been removed."); |
| |
| // Android-changed: Copy-on-read List of listeners, not copy-on-write array. |
| /* |
| // Copy-on-write |
| if (nodeListeners == null) { |
| nodeListeners = new NodeChangeListener[1]; |
| nodeListeners[0] = ncl; |
| } else { |
| NodeChangeListener[] old = nodeListeners; |
| nodeListeners = new NodeChangeListener[old.length + 1]; |
| System.arraycopy(old, 0, nodeListeners, 0, old.length); |
| nodeListeners[old.length] = ncl; |
| } |
| */ |
| nodeListeners.add(ncl); |
| } |
| startEventDispatchThreadIfNecessary(); |
| } |
| |
| public void removeNodeChangeListener(NodeChangeListener ncl) { |
| synchronized(lock) { |
| if (removed) |
| throw new IllegalStateException("Node has been removed."); |
| // Android-changed: Copy-on-read List of listeners, not copy-on-write array. |
| // if ((nodeListeners == null) || (nodeListeners.length == 0)) |
| if (!nodeListeners.contains(ncl)) { |
| throw new IllegalArgumentException("Listener not registered."); |
| } |
| |
| // Android-changed: Copy-on-read List of listeners, not copy-on-write array. |
| /* |
| // Copy-on-write |
| int i = 0; |
| while (i < nodeListeners.length && nodeListeners[i] != ncl) |
| i++; |
| if (i == nodeListeners.length) |
| throw new IllegalArgumentException("Listener not registered."); |
| NodeChangeListener[] newNl = |
| new NodeChangeListener[nodeListeners.length - 1]; |
| if (i != 0) |
| System.arraycopy(nodeListeners, 0, newNl, 0, i); |
| if (i != newNl.length) |
| System.arraycopy(nodeListeners, i + 1, |
| newNl, i, newNl.length - i); |
| nodeListeners = newNl; |
| */ |
| nodeListeners.remove(ncl); |
| } |
| } |
| |
| // "SPI" METHODS |
| |
| /** |
| * Put the given key-value association into this preference node. It is |
| * guaranteed that <tt>key</tt> and <tt>value</tt> are non-null and of |
| * legal length. Also, it is guaranteed that this node has not been |
| * removed. (The implementor needn't check for any of these things.) |
| * |
| * <p>This method is invoked with the lock on this node held. |
| * @param key the key |
| * @param value the value |
| */ |
| protected abstract void putSpi(String key, String value); |
| |
| /** |
| * Return the value associated with the specified key at this preference |
| * node, or <tt>null</tt> if there is no association for this key, or the |
| * association cannot be determined at this time. It is guaranteed that |
| * <tt>key</tt> is non-null. Also, it is guaranteed that this node has |
| * not been removed. (The implementor needn't check for either of these |
| * things.) |
| * |
| * <p> Generally speaking, this method should not throw an exception |
| * under any circumstances. If, however, if it does throw an exception, |
| * the exception will be intercepted and treated as a <tt>null</tt> |
| * return value. |
| * |
| * <p>This method is invoked with the lock on this node held. |
| * |
| * @param key the key |
| * @return the value associated with the specified key at this preference |
| * node, or <tt>null</tt> if there is no association for this |
| * key, or the association cannot be determined at this time. |
| */ |
| protected abstract String getSpi(String key); |
| |
| /** |
| * Remove the association (if any) for the specified key at this |
| * preference node. It is guaranteed that <tt>key</tt> is non-null. |
| * Also, it is guaranteed that this node has not been removed. |
| * (The implementor needn't check for either of these things.) |
| * |
| * <p>This method is invoked with the lock on this node held. |
| * @param key the key |
| */ |
| protected abstract void removeSpi(String key); |
| |
| /** |
| * Removes this preference node, invalidating it and any preferences that |
| * it contains. The named child will have no descendants at the time this |
| * invocation is made (i.e., the {@link Preferences#removeNode()} method |
| * invokes this method repeatedly in a bottom-up fashion, removing each of |
| * a node's descendants before removing the node itself). |
| * |
| * <p>This method is invoked with the lock held on this node and its |
| * parent (and all ancestors that are being removed as a |
| * result of a single invocation to {@link Preferences#removeNode()}). |
| * |
| * <p>The removal of a node needn't become persistent until the |
| * <tt>flush</tt> method is invoked on this node (or an ancestor). |
| * |
| * <p>If this node throws a <tt>BackingStoreException</tt>, the exception |
| * will propagate out beyond the enclosing {@link #removeNode()} |
| * invocation. |
| * |
| * @throws BackingStoreException if this operation cannot be completed |
| * due to a failure in the backing store, or inability to |
| * communicate with it. |
| */ |
| protected abstract void removeNodeSpi() throws BackingStoreException; |
| |
| /** |
| * Returns all of the keys that have an associated value in this |
| * preference node. (The returned array will be of size zero if |
| * this node has no preferences.) It is guaranteed that this node has not |
| * been removed. |
| * |
| * <p>This method is invoked with the lock on this node held. |
| * |
| * <p>If this node throws a <tt>BackingStoreException</tt>, the exception |
| * will propagate out beyond the enclosing {@link #keys()} invocation. |
| * |
| * @return an array of the keys that have an associated value in this |
| * preference node. |
| * @throws BackingStoreException if this operation cannot be completed |
| * due to a failure in the backing store, or inability to |
| * communicate with it. |
| */ |
| protected abstract String[] keysSpi() throws BackingStoreException; |
| |
| /** |
| * Returns the names of the children of this preference node. (The |
| * returned array will be of size zero if this node has no children.) |
| * This method need not return the names of any nodes already cached, |
| * but may do so without harm. |
| * |
| * <p>This method is invoked with the lock on this node held. |
| * |
| * <p>If this node throws a <tt>BackingStoreException</tt>, the exception |
| * will propagate out beyond the enclosing {@link #childrenNames()} |
| * invocation. |
| * |
| * @return an array containing the names of the children of this |
| * preference node. |
| * @throws BackingStoreException if this operation cannot be completed |
| * due to a failure in the backing store, or inability to |
| * communicate with it. |
| */ |
| protected abstract String[] childrenNamesSpi() |
| throws BackingStoreException; |
| |
| /** |
| * Returns the named child if it exists, or <tt>null</tt> if it does not. |
| * It is guaranteed that <tt>nodeName</tt> is non-null, non-empty, |
| * does not contain the slash character ('/'), and is no longer than |
| * {@link #MAX_NAME_LENGTH} characters. Also, it is guaranteed |
| * that this node has not been removed. (The implementor needn't check |
| * for any of these things if he chooses to override this method.) |
| * |
| * <p>Finally, it is guaranteed that the named node has not been returned |
| * by a previous invocation of this method or {@link #childSpi} after the |
| * last time that it was removed. In other words, a cached value will |
| * always be used in preference to invoking this method. (The implementor |
| * needn't maintain his own cache of previously returned children if he |
| * chooses to override this method.) |
| * |
| * <p>This implementation obtains this preference node's lock, invokes |
| * {@link #childrenNames()} to get an array of the names of this node's |
| * children, and iterates over the array comparing the name of each child |
| * with the specified node name. If a child node has the correct name, |
| * the {@link #childSpi(String)} method is invoked and the resulting |
| * node is returned. If the iteration completes without finding the |
| * specified name, <tt>null</tt> is returned. |
| * |
| * @param nodeName name of the child to be searched for. |
| * @return the named child if it exists, or null if it does not. |
| * @throws BackingStoreException if this operation cannot be completed |
| * due to a failure in the backing store, or inability to |
| * communicate with it. |
| */ |
| protected AbstractPreferences getChild(String nodeName) |
| throws BackingStoreException { |
| synchronized(lock) { |
| // assert kidCache.get(nodeName)==null; |
| String[] kidNames = childrenNames(); |
| for (int i=0; i<kidNames.length; i++) |
| if (kidNames[i].equals(nodeName)) |
| return childSpi(kidNames[i]); |
| } |
| return null; |
| } |
| |
| /** |
| * Returns the named child of this preference node, creating it if it does |
| * not already exist. It is guaranteed that <tt>name</tt> is non-null, |
| * non-empty, does not contain the slash character ('/'), and is no longer |
| * than {@link #MAX_NAME_LENGTH} characters. Also, it is guaranteed that |
| * this node has not been removed. (The implementor needn't check for any |
| * of these things.) |
| * |
| * <p>Finally, it is guaranteed that the named node has not been returned |
| * by a previous invocation of this method or {@link #getChild(String)} |
| * after the last time that it was removed. In other words, a cached |
| * value will always be used in preference to invoking this method. |
| * Subclasses need not maintain their own cache of previously returned |
| * children. |
| * |
| * <p>The implementer must ensure that the returned node has not been |
| * removed. If a like-named child of this node was previously removed, the |
| * implementer must return a newly constructed <tt>AbstractPreferences</tt> |
| * node; once removed, an <tt>AbstractPreferences</tt> node |
| * cannot be "resuscitated." |
| * |
| * <p>If this method causes a node to be created, this node is not |
| * guaranteed to be persistent until the <tt>flush</tt> method is |
| * invoked on this node or one of its ancestors (or descendants). |
| * |
| * <p>This method is invoked with the lock on this node held. |
| * |
| * @param name The name of the child node to return, relative to |
| * this preference node. |
| * @return The named child node. |
| */ |
| protected abstract AbstractPreferences childSpi(String name); |
| |
| /** |
| * Returns the absolute path name of this preferences node. |
| */ |
| public String toString() { |
| return (this.isUserNode() ? "User" : "System") + |
| " Preference Node: " + this.absolutePath(); |
| } |
| |
| /** |
| * Implements the <tt>sync</tt> method as per the specification in |
| * {@link Preferences#sync()}. |
| * |
| * <p>This implementation calls a recursive helper method that locks this |
| * node, invokes syncSpi() on it, unlocks this node, and recursively |
| * invokes this method on each "cached child." A cached child is a child |
| * of this node that has been created in this VM and not subsequently |
| * removed. In effect, this method does a depth first traversal of the |
| * "cached subtree" rooted at this node, calling syncSpi() on each node in |
| * the subTree while only that node is locked. Note that syncSpi() is |
| * invoked top-down. |
| * |
| * @throws BackingStoreException if this operation cannot be completed |
| * due to a failure in the backing store, or inability to |
| * communicate with it. |
| * @throws IllegalStateException if this node (or an ancestor) has been |
| * removed with the {@link #removeNode()} method. |
| * @see #flush() |
| */ |
| public void sync() throws BackingStoreException { |
| sync2(); |
| } |
| |
| private void sync2() throws BackingStoreException { |
| AbstractPreferences[] cachedKids; |
| |
| synchronized(lock) { |
| if (removed) |
| throw new IllegalStateException("Node has been removed"); |
| syncSpi(); |
| cachedKids = cachedChildren(); |
| } |
| |
| for (int i=0; i<cachedKids.length; i++) |
| cachedKids[i].sync2(); |
| } |
| |
| /** |
| * This method is invoked with this node locked. The contract of this |
| * method is to synchronize any cached preferences stored at this node |
| * with any stored in the backing store. (It is perfectly possible that |
| * this node does not exist on the backing store, either because it has |
| * been deleted by another VM, or because it has not yet been created.) |
| * Note that this method should <i>not</i> synchronize the preferences in |
| * any subnodes of this node. If the backing store naturally syncs an |
| * entire subtree at once, the implementer is encouraged to override |
| * sync(), rather than merely overriding this method. |
| * |
| * <p>If this node throws a <tt>BackingStoreException</tt>, the exception |
| * will propagate out beyond the enclosing {@link #sync()} invocation. |
| * |
| * @throws BackingStoreException if this operation cannot be completed |
| * due to a failure in the backing store, or inability to |
| * communicate with it. |
| */ |
| protected abstract void syncSpi() throws BackingStoreException; |
| |
| /** |
| * Implements the <tt>flush</tt> method as per the specification in |
| * {@link Preferences#flush()}. |
| * |
| * <p>This implementation calls a recursive helper method that locks this |
| * node, invokes flushSpi() on it, unlocks this node, and recursively |
| * invokes this method on each "cached child." A cached child is a child |
| * of this node that has been created in this VM and not subsequently |
| * removed. In effect, this method does a depth first traversal of the |
| * "cached subtree" rooted at this node, calling flushSpi() on each node in |
| * the subTree while only that node is locked. Note that flushSpi() is |
| * invoked top-down. |
| * |
| * <p> If this method is invoked on a node that has been removed with |
| * the {@link #removeNode()} method, flushSpi() is invoked on this node, |
| * but not on others. |
| * |
| * @throws BackingStoreException if this operation cannot be completed |
| * due to a failure in the backing store, or inability to |
| * communicate with it. |
| * @see #flush() |
| */ |
| public void flush() throws BackingStoreException { |
| flush2(); |
| } |
| |
| private void flush2() throws BackingStoreException { |
| AbstractPreferences[] cachedKids; |
| |
| synchronized(lock) { |
| flushSpi(); |
| if(removed) |
| return; |
| cachedKids = cachedChildren(); |
| } |
| |
| for (int i = 0; i < cachedKids.length; i++) |
| cachedKids[i].flush2(); |
| } |
| |
| /** |
| * This method is invoked with this node locked. The contract of this |
| * method is to force any cached changes in the contents of this |
| * preference node to the backing store, guaranteeing their persistence. |
| * (It is perfectly possible that this node does not exist on the backing |
| * store, either because it has been deleted by another VM, or because it |
| * has not yet been created.) Note that this method should <i>not</i> |
| * flush the preferences in any subnodes of this node. If the backing |
| * store naturally flushes an entire subtree at once, the implementer is |
| * encouraged to override flush(), rather than merely overriding this |
| * method. |
| * |
| * <p>If this node throws a <tt>BackingStoreException</tt>, the exception |
| * will propagate out beyond the enclosing {@link #flush()} invocation. |
| * |
| * @throws BackingStoreException if this operation cannot be completed |
| * due to a failure in the backing store, or inability to |
| * communicate with it. |
| */ |
| protected abstract void flushSpi() throws BackingStoreException; |
| |
| /** |
| * Returns <tt>true</tt> iff this node (or an ancestor) has been |
| * removed with the {@link #removeNode()} method. This method |
| * locks this node prior to returning the contents of the private |
| * field used to track this state. |
| * |
| * @return <tt>true</tt> iff this node (or an ancestor) has been |
| * removed with the {@link #removeNode()} method. |
| */ |
| protected boolean isRemoved() { |
| synchronized(lock) { |
| return removed; |
| } |
| } |
| |
| /** |
| * Queue of pending notification events. When a preference or node |
| * change event for which there are one or more listeners occurs, |
| * it is placed on this queue and the queue is notified. A background |
| * thread waits on this queue and delivers the events. This decouples |
| * event delivery from preference activity, greatly simplifying |
| * locking and reducing opportunity for deadlock. |
| */ |
| private static final List<EventObject> eventQueue = new LinkedList<>(); |
| |
| /** |
| * These two classes are used to distinguish NodeChangeEvents on |
| * eventQueue so the event dispatch thread knows whether to call |
| * childAdded or childRemoved. |
| */ |
| private class NodeAddedEvent extends NodeChangeEvent { |
| private static final long serialVersionUID = -6743557530157328528L; |
| NodeAddedEvent(Preferences parent, Preferences child) { |
| super(parent, child); |
| } |
| } |
| private class NodeRemovedEvent extends NodeChangeEvent { |
| private static final long serialVersionUID = 8735497392918824837L; |
| NodeRemovedEvent(Preferences parent, Preferences child) { |
| super(parent, child); |
| } |
| } |
| |
| /** |
| * A single background thread ("the event notification thread") monitors |
| * the event queue and delivers events that are placed on the queue. |
| */ |
| private static class EventDispatchThread extends Thread { |
| public void run() { |
| while(true) { |
| // Wait on eventQueue till an event is present |
| EventObject event = null; |
| synchronized(eventQueue) { |
| try { |
| while (eventQueue.isEmpty()) |
| eventQueue.wait(); |
| event = eventQueue.remove(0); |
| } catch (InterruptedException e) { |
| // XXX Log "Event dispatch thread interrupted. Exiting" |
| return; |
| } |
| } |
| |
| // Now we have event & hold no locks; deliver evt to listeners |
| AbstractPreferences src=(AbstractPreferences)event.getSource(); |
| if (event instanceof PreferenceChangeEvent) { |
| PreferenceChangeEvent pce = (PreferenceChangeEvent)event; |
| PreferenceChangeListener[] listeners = src.prefListeners(); |
| for (int i=0; i<listeners.length; i++) |
| listeners[i].preferenceChange(pce); |
| } else { |
| NodeChangeEvent nce = (NodeChangeEvent)event; |
| NodeChangeListener[] listeners = src.nodeListeners(); |
| if (nce instanceof NodeAddedEvent) { |
| for (int i=0; i<listeners.length; i++) |
| listeners[i].childAdded(nce); |
| } else { |
| // assert nce instanceof NodeRemovedEvent; |
| for (int i=0; i<listeners.length; i++) |
| listeners[i].childRemoved(nce); |
| } |
| } |
| } |
| } |
| } |
| |
| private static Thread eventDispatchThread = null; |
| |
| /** |
| * This method starts the event dispatch thread the first time it |
| * is called. The event dispatch thread will be started only |
| * if someone registers a listener. |
| */ |
| private static synchronized void startEventDispatchThreadIfNecessary() { |
| if (eventDispatchThread == null) { |
| // XXX Log "Starting event dispatch thread" |
| eventDispatchThread = new EventDispatchThread(); |
| eventDispatchThread.setDaemon(true); |
| eventDispatchThread.start(); |
| } |
| } |
| |
| // BEGIN Android-changed: Copy-on-read List of listeners, not copy-on-write array. |
| // Changed documentation. |
| /* |
| /** |
| * Return this node's preference/node change listeners. Even though |
| * we're using a copy-on-write lists, we use synchronized accessors to |
| * ensure information transmission from the writing thread to the |
| * reading thread. |
| * |
| */ |
| /** |
| * Return this node's preference/node change listeners. All accesses to prefListeners |
| * and nodeListeners are guarded by |lock|. We return a copy of the list so that the |
| * EventQueue thread will iterate over a fixed snapshot of the listeners at the time of |
| * this call. |
| */ |
| // END Android-changed: Copy-on-read List of listeners, not copy-on-write array. |
| PreferenceChangeListener[] prefListeners() { |
| synchronized(lock) { |
| // Android-changed: Copy-on-read List of listeners, not copy-on-write array. |
| // return prefListeners; |
| return prefListeners.toArray(new PreferenceChangeListener[prefListeners.size()]); |
| } |
| } |
| NodeChangeListener[] nodeListeners() { |
| synchronized(lock) { |
| // Android-changed: Copy-on-read List of listeners, not copy-on-write array. |
| // return nodeListeners; |
| return nodeListeners.toArray(new NodeChangeListener[nodeListeners.size()]); |
| } |
| } |
| |
| /** |
| * Enqueue a preference change event for delivery to registered |
| * preference change listeners unless there are no registered |
| * listeners. Invoked with this.lock held. |
| */ |
| private void enqueuePreferenceChangeEvent(String key, String newValue) { |
| // Android-changed: Copy-on-read List of listeners, not copy-on-write array. |
| // if (prefListeners.length != 0) { |
| if (!prefListeners.isEmpty()) { |
| synchronized(eventQueue) { |
| eventQueue.add(new PreferenceChangeEvent(this, key, newValue)); |
| eventQueue.notify(); |
| } |
| } |
| } |
| |
| /** |
| * Enqueue a "node added" event for delivery to registered node change |
| * listeners unless there are no registered listeners. Invoked with |
| * this.lock held. |
| */ |
| private void enqueueNodeAddedEvent(Preferences child) { |
| // Android-changed: Copy-on-read List of listeners, not copy-on-write array. |
| // if (nodeListeners.length != 0) { |
| if (!nodeListeners.isEmpty()) { |
| synchronized(eventQueue) { |
| eventQueue.add(new NodeAddedEvent(this, child)); |
| eventQueue.notify(); |
| } |
| } |
| } |
| |
| /** |
| * Enqueue a "node removed" event for delivery to registered node change |
| * listeners unless there are no registered listeners. Invoked with |
| * this.lock held. |
| */ |
| private void enqueueNodeRemovedEvent(Preferences child) { |
| // Android-changed: Copy-on-read List of listeners, not copy-on-write array. |
| // if (nodeListeners.length != 0) { |
| if (!nodeListeners.isEmpty()) { |
| synchronized(eventQueue) { |
| eventQueue.add(new NodeRemovedEvent(this, child)); |
| eventQueue.notify(); |
| } |
| } |
| } |
| |
| /** |
| * Implements the <tt>exportNode</tt> method as per the specification in |
| * {@link Preferences#exportNode(OutputStream)}. |
| * |
| * @param os the output stream on which to emit the XML document. |
| * @throws IOException if writing to the specified output stream |
| * results in an <tt>IOException</tt>. |
| * @throws BackingStoreException if preference data cannot be read from |
| * backing store. |
| */ |
| public void exportNode(OutputStream os) |
| throws IOException, BackingStoreException |
| { |
| XmlSupport.export(os, this, false); |
| } |
| |
| /** |
| * Implements the <tt>exportSubtree</tt> method as per the specification in |
| * {@link Preferences#exportSubtree(OutputStream)}. |
| * |
| * @param os the output stream on which to emit the XML document. |
| * @throws IOException if writing to the specified output stream |
| * results in an <tt>IOException</tt>. |
| * @throws BackingStoreException if preference data cannot be read from |
| * backing store. |
| */ |
| public void exportSubtree(OutputStream os) |
| throws IOException, BackingStoreException |
| { |
| XmlSupport.export(os, this, true); |
| } |
| } |
