001 /* AbstractPreferences -- Partial implementation of a Preference node
002 Copyright (C) 2001, 2003, 2004, 2006 Free Software Foundation, Inc.
003
004 This file is part of GNU Classpath.
005
006 GNU Classpath is free software; you can redistribute it and/or modify
007 it under the terms of the GNU General Public License as published by
008 the Free Software Foundation; either version 2, or (at your option)
009 any later version.
010
011 GNU Classpath is distributed in the hope that it will be useful, but
012 WITHOUT ANY WARRANTY; without even the implied warranty of
013 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
014 General Public License for more details.
015
016 You should have received a copy of the GNU General Public License
017 along with GNU Classpath; see the file COPYING. If not, write to the
018 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019 02110-1301 USA.
020
021 Linking this library statically or dynamically with other modules is
022 making a combined work based on this library. Thus, the terms and
023 conditions of the GNU General Public License cover the whole
024 combination.
025
026 As a special exception, the copyright holders of this library give you
027 permission to link this library with independent modules to produce an
028 executable, regardless of the license terms of these independent
029 modules, and to copy and distribute the resulting executable under
030 terms of your choice, provided that you also meet, for each linked
031 independent module, the terms and conditions of the license of that
032 module. An independent module is a module which is not derived from
033 or based on this library. If you modify this library, you may extend
034 this exception to your version of the library, but you are not
035 obligated to do so. If you do not wish to do so, delete this
036 exception statement from your version. */
037
038
039 package java.util.prefs;
040
041 import gnu.classpath.toolkit.DefaultDaemonThreadFactory;
042 import gnu.java.lang.CPStringBuilder;
043 import gnu.java.util.prefs.NodeWriter;
044
045 import java.io.ByteArrayOutputStream;
046 import java.io.IOException;
047 import java.io.OutputStream;
048 import java.util.ArrayList;
049 import java.util.Collection;
050 import java.util.HashMap;
051 import java.util.Iterator;
052 import java.util.TreeSet;
053 import java.util.concurrent.Executor;
054 import java.util.concurrent.Executors;
055
056 /**
057 * Partial implementation of a Preference node.
058 *
059 * @since 1.4
060 * @author Mark Wielaard (mark@klomp.org)
061 */
062 public abstract class AbstractPreferences extends Preferences {
063
064 // protected fields
065
066 /**
067 * Object used to lock this preference node. Any thread only locks nodes
068 * downwards when it has the lock on the current node. No method should
069 * synchronize on the lock of any of its parent nodes while holding the
070 * lock on the current node.
071 */
072 protected final Object lock = new Object();
073
074 /**
075 * Set to true in the contructor if the node did not exist in the backing
076 * store when this preference node object was created. Should be set in
077 * the constructor of a subclass. Defaults to false. Used to fire node
078 * changed events.
079 */
080 protected boolean newNode = false;
081
082 // private fields
083
084 /**
085 * The parent preferences node or null when this is the root node.
086 */
087 private final AbstractPreferences parent;
088
089 /**
090 * The name of this node.
091 * Only when this is a root node (parent == null) the name is empty.
092 * It has a maximum of 80 characters and cannot contain any '/' characters.
093 */
094 private final String name;
095
096 /** True when this node has been remove, false otherwise. */
097 private boolean removed = false;
098
099 /**
100 * Holds all the child names and nodes of this node that have been
101 * accessed by earlier <code>getChild()</code> or <code>childSpi()</code>
102 * invocations and that have not been removed.
103 */
104 private HashMap<String, AbstractPreferences> childCache
105 = new HashMap<String, AbstractPreferences>();
106
107 /**
108 * A list of all the registered NodeChangeListener objects.
109 */
110 private ArrayList<NodeChangeListener> nodeListeners;
111
112 /**
113 * A list of all the registered PreferenceChangeListener objects.
114 */
115 private ArrayList<PreferenceChangeListener> preferenceListeners;
116
117 // constructor
118
119 /**
120 * Creates a new AbstractPreferences node with the given parent and name.
121 *
122 * @param parent the parent of this node or null when this is the root node
123 * @param name the name of this node, can not be null, only 80 characters
124 * maximum, must be empty when parent is null and cannot
125 * contain any '/' characters
126 * @exception IllegalArgumentException when name is null, greater then 80
127 * characters, not the empty string but parent is null or
128 * contains a '/' character
129 */
130 protected AbstractPreferences(AbstractPreferences parent, String name) {
131 if ( (name == null) // name should be given
132 || (name.length() > MAX_NAME_LENGTH) // 80 characters max
133 || (parent == null && name.length() != 0) // root has no name
134 || (parent != null && name.length() == 0) // all other nodes do
135 || (name.indexOf('/') != -1)) // must not contain '/'
136 throw new IllegalArgumentException("Illegal name argument '"
137 + name
138 + "' (parent is "
139 + (parent == null ? "" : "not ")
140 + "null)");
141 this.parent = parent;
142 this.name = name;
143 }
144
145 // identification methods
146
147 /**
148 * Returns the absolute path name of this preference node.
149 * The absolute path name of a node is the path name of its parent node
150 * plus a '/' plus its own name. If the node is the root node and has no
151 * parent then its path name is "" and its absolute path name is "/".
152 */
153 public String absolutePath() {
154 if (parent == null)
155 return "/";
156 else
157 return parent.path() + '/' + name;
158 }
159
160 /**
161 * Private helper method for absolutePath. Returns the empty string for a
162 * root node and otherwise the parentPath of its parent plus a '/'.
163 */
164 private String path() {
165 if (parent == null)
166 return "";
167 else
168 return parent.path() + '/' + name;
169 }
170
171 /**
172 * Returns true if this node comes from the user preferences tree, false
173 * if it comes from the system preferences tree.
174 */
175 public boolean isUserNode() {
176 AbstractPreferences root = this;
177 while (root.parent != null)
178 root = root.parent;
179 return root == Preferences.userRoot();
180 }
181
182 /**
183 * Returns the name of this preferences node. The name of the node cannot
184 * be null, can be mostly 80 characters and cannot contain any '/'
185 * characters. The root node has as name "".
186 */
187 public String name() {
188 return name;
189 }
190
191 /**
192 * Returns the String given by
193 * <code>
194 * (isUserNode() ? "User":"System") + " Preference Node: " + absolutePath()
195 * </code>
196 */
197 public String toString() {
198 return (isUserNode() ? "User":"System")
199 + " Preference Node: "
200 + absolutePath();
201 }
202
203 /**
204 * Returns all known unremoved children of this node.
205 *
206 * @return All known unremoved children of this node
207 */
208 protected final AbstractPreferences[] cachedChildren()
209 {
210 Collection<AbstractPreferences> vals = childCache.values();
211 return vals.toArray(new AbstractPreferences[vals.size()]);
212 }
213
214 /**
215 * Returns all the direct sub nodes of this preferences node.
216 * Needs access to the backing store to give a meaningfull answer.
217 * <p>
218 * This implementation locks this node, checks if the node has not yet
219 * been removed and throws an <code>IllegalStateException</code> when it
220 * has been. Then it creates a new <code>TreeSet</code> and adds any
221 * already cached child nodes names. To get any uncached names it calls
222 * <code>childrenNamesSpi()</code> and adds the result to the set. Finally
223 * it calls <code>toArray()</code> on the created set. When the call to
224 * <code>childrenNamesSpi</code> thows an <code>BackingStoreException</code>
225 * this method will not catch that exception but propagate the exception
226 * to the caller.
227 *
228 * @exception BackingStoreException when the backing store cannot be
229 * reached
230 * @exception IllegalStateException when this node has been removed
231 */
232 public String[] childrenNames() throws BackingStoreException {
233 synchronized(lock) {
234 if (isRemoved())
235 throw new IllegalStateException("Node removed");
236
237 TreeSet<String> childrenNames = new TreeSet<String>();
238
239 // First get all cached node names
240 childrenNames.addAll(childCache.keySet());
241
242 // Then add any others
243 String names[] = childrenNamesSpi();
244 for (int i = 0; i < names.length; i++) {
245 childrenNames.add(names[i]);
246 }
247
248 // And return the array of names
249 String[] children = new String[childrenNames.size()];
250 childrenNames.toArray(children);
251 return children;
252
253 }
254 }
255
256 /**
257 * Returns a sub node of this preferences node if the given path is
258 * relative (does not start with a '/') or a sub node of the root
259 * if the path is absolute (does start with a '/').
260 * <p>
261 * This method first locks this node and checks if the node has not been
262 * removed, if it has been removed it throws an exception. Then if the
263 * path is relative (does not start with a '/') it checks if the path is
264 * legal (does not end with a '/' and has no consecutive '/' characters).
265 * Then it recursively gets a name from the path, gets the child node
266 * from the child-cache of this node or calls the <code>childSpi()</code>
267 * method to create a new child sub node. This is done recursively on the
268 * newly created sub node with the rest of the path till the path is empty.
269 * If the path is absolute (starts with a '/') the lock on this node is
270 * droped and this method is called on the root of the preferences tree
271 * with as argument the complete path minus the first '/'.
272 *
273 * @exception IllegalStateException if this node has been removed
274 * @exception IllegalArgumentException if the path contains two or more
275 * consecutive '/' characters, ends with a '/' charactor and is not the
276 * string "/" (indicating the root node) or any name on the path is more
277 * than 80 characters long
278 */
279 public Preferences node(String path) {
280 synchronized(lock) {
281 if (isRemoved())
282 throw new IllegalStateException("Node removed");
283
284 // Is it a relative path?
285 if (!path.startsWith("/")) {
286
287 // Check if it is a valid path
288 if (path.indexOf("//") != -1 || path.endsWith("/"))
289 throw new IllegalArgumentException(path);
290
291 return getNode(path);
292 }
293 }
294
295 // path started with a '/' so it is absolute
296 // we drop the lock and start from the root (omitting the first '/')
297 Preferences root = isUserNode() ? userRoot() : systemRoot();
298 return root.node(path.substring(1));
299
300 }
301
302 /**
303 * Private helper method for <code>node()</code>. Called with this node
304 * locked. Returns this node when path is the empty string, if it is not
305 * empty the next node name is taken from the path (all chars till the
306 * next '/' or end of path string) and the node is either taken from the
307 * child-cache of this node or the <code>childSpi()</code> method is called
308 * on this node with the name as argument. Then this method is called
309 * recursively on the just constructed child node with the rest of the
310 * path.
311 *
312 * @param path should not end with a '/' character and should not contain
313 * consecutive '/' characters
314 * @exception IllegalArgumentException if path begins with a name that is
315 * larger then 80 characters.
316 */
317 private Preferences getNode(String path) {
318 // if mark is dom then goto end
319
320 // Empty String "" indicates this node
321 if (path.length() == 0)
322 return this;
323
324 // Calculate child name and rest of path
325 String childName;
326 String childPath;
327 int nextSlash = path.indexOf('/');
328 if (nextSlash == -1) {
329 childName = path;
330 childPath = "";
331 } else {
332 childName = path.substring(0, nextSlash);
333 childPath = path.substring(nextSlash+1);
334 }
335
336 // Get the child node
337 AbstractPreferences child;
338 child = (AbstractPreferences)childCache.get(childName);
339 if (child == null) {
340
341 if (childName.length() > MAX_NAME_LENGTH)
342 throw new IllegalArgumentException(childName);
343
344 // Not in childCache yet so create a new sub node
345 child = childSpi(childName);
346 childCache.put(childName, child);
347 if (child.newNode && nodeListeners != null)
348 fire(new NodeChangeEvent(this, child), true);
349 }
350
351 // Lock the child and go down
352 synchronized(child.lock) {
353 return child.getNode(childPath);
354 }
355 }
356
357 /**
358 * Returns true if the node that the path points to exists in memory or
359 * in the backing store. Otherwise it returns false or an exception is
360 * thrown. When this node is removed the only valid parameter is the
361 * empty string (indicating this node), the return value in that case
362 * will be false.
363 *
364 * @exception BackingStoreException when the backing store cannot be
365 * reached
366 * @exception IllegalStateException if this node has been removed
367 * and the path is not the empty string (indicating this node)
368 * @exception IllegalArgumentException if the path contains two or more
369 * consecutive '/' characters, ends with a '/' charactor and is not the
370 * string "/" (indicating the root node) or any name on the path is more
371 * then 80 characters long
372 */
373 public boolean nodeExists(String path) throws BackingStoreException {
374 synchronized(lock) {
375 if (isRemoved() && path.length() != 0)
376 throw new IllegalStateException("Node removed");
377
378 // Is it a relative path?
379 if (!path.startsWith("/")) {
380
381 // Check if it is a valid path
382 if (path.indexOf("//") != -1 || path.endsWith("/"))
383 throw new IllegalArgumentException(path);
384
385 return existsNode(path);
386 }
387 }
388
389 // path started with a '/' so it is absolute
390 // we drop the lock and start from the root (omitting the first '/')
391 Preferences root = isUserNode() ? userRoot() : systemRoot();
392 return root.nodeExists(path.substring(1));
393
394 }
395
396 private boolean existsNode(String path) throws BackingStoreException {
397
398 // Empty String "" indicates this node
399 if (path.length() == 0)
400 return(!isRemoved());
401
402 // Calculate child name and rest of path
403 String childName;
404 String childPath;
405 int nextSlash = path.indexOf('/');
406 if (nextSlash == -1) {
407 childName = path;
408 childPath = "";
409 } else {
410 childName = path.substring(0, nextSlash);
411 childPath = path.substring(nextSlash+1);
412 }
413
414 // Get the child node
415 AbstractPreferences child;
416 child = (AbstractPreferences)childCache.get(childName);
417 if (child == null) {
418
419 if (childName.length() > MAX_NAME_LENGTH)
420 throw new IllegalArgumentException(childName);
421
422 // Not in childCache yet so create a new sub node
423 child = getChild(childName);
424
425 if (child == null)
426 return false;
427
428 childCache.put(childName, child);
429 }
430
431 // Lock the child and go down
432 synchronized(child.lock) {
433 return child.existsNode(childPath);
434 }
435 }
436
437 /**
438 * Returns the child sub node if it exists in the backing store or null
439 * if it does not exist. Called (indirectly) by <code>nodeExists()</code>
440 * when a child node name can not be found in the cache.
441 * <p>
442 * Gets the lock on this node, calls <code>childrenNamesSpi()</code> to
443 * get an array of all (possibly uncached) children and compares the
444 * given name with the names in the array. If the name is found in the
445 * array <code>childSpi()</code> is called to get an instance, otherwise
446 * null is returned.
447 *
448 * @exception BackingStoreException when the backing store cannot be
449 * reached
450 */
451 protected AbstractPreferences getChild(String name)
452 throws BackingStoreException
453 {
454 synchronized(lock) {
455 // Get all the names (not yet in the cache)
456 String[] names = childrenNamesSpi();
457 for (int i=0; i < names.length; i++)
458 if (name.equals(names[i]))
459 return childSpi(name);
460
461 // No child with that name found
462 return null;
463 }
464 }
465
466 /**
467 * Returns true if this node has been removed with the
468 * <code>removeNode()</code> method, false otherwise.
469 * <p>
470 * Gets the lock on this node and then returns a boolean field set by
471 * <code>removeNode</code> methods.
472 */
473 protected boolean isRemoved() {
474 synchronized(lock) {
475 return removed;
476 }
477 }
478
479 /**
480 * Returns the parent preferences node of this node or null if this is
481 * the root of the preferences tree.
482 * <p>
483 * Gets the lock on this node, checks that the node has not been removed
484 * and returns the parent given to the constructor.
485 *
486 * @exception IllegalStateException if this node has been removed
487 */
488 public Preferences parent() {
489 synchronized(lock) {
490 if (isRemoved())
491 throw new IllegalStateException("Node removed");
492
493 return parent;
494 }
495 }
496
497 // export methods
498
499 // Inherit javadoc.
500 public void exportNode(OutputStream os)
501 throws BackingStoreException,
502 IOException
503 {
504 NodeWriter nodeWriter = new NodeWriter(this, os);
505 nodeWriter.writePrefs();
506 }
507
508 // Inherit javadoc.
509 public void exportSubtree(OutputStream os)
510 throws BackingStoreException,
511 IOException
512 {
513 NodeWriter nodeWriter = new NodeWriter(this, os);
514 nodeWriter.writePrefsTree();
515 }
516
517 // preference entry manipulation methods
518
519 /**
520 * Returns an (possibly empty) array with all the keys of the preference
521 * entries of this node.
522 * <p>
523 * This method locks this node and checks if the node has not been
524 * removed, if it has been removed it throws an exception, then it returns
525 * the result of calling <code>keysSpi()</code>.
526 *
527 * @exception BackingStoreException when the backing store cannot be
528 * reached
529 * @exception IllegalStateException if this node has been removed
530 */
531 public String[] keys() throws BackingStoreException {
532 synchronized(lock) {
533 if (isRemoved())
534 throw new IllegalStateException("Node removed");
535
536 return keysSpi();
537 }
538 }
539
540
541 /**
542 * Returns the value associated with the key in this preferences node. If
543 * the default value of the key cannot be found in the preferences node
544 * entries or something goes wrong with the backing store the supplied
545 * default value is returned.
546 * <p>
547 * Checks that key is not null and not larger then 80 characters,
548 * locks this node, and checks that the node has not been removed.
549 * Then it calls <code>keySpi()</code> and returns
550 * the result of that method or the given default value if it returned
551 * null or throwed an exception.
552 *
553 * @exception IllegalArgumentException if key is larger then 80 characters
554 * @exception IllegalStateException if this node has been removed
555 * @exception NullPointerException if key is null
556 */
557 public String get(String key, String defaultVal) {
558 if (key.length() > MAX_KEY_LENGTH)
559 throw new IllegalArgumentException(key);
560
561 synchronized(lock) {
562 if (isRemoved())
563 throw new IllegalStateException("Node removed");
564
565 String value;
566 try {
567 value = getSpi(key);
568 } catch (ThreadDeath death) {
569 throw death;
570 } catch (Throwable t) {
571 value = null;
572 }
573
574 if (value != null) {
575 return value;
576 } else {
577 return defaultVal;
578 }
579 }
580 }
581
582 /**
583 * Convenience method for getting the given entry as a boolean.
584 * When the string representation of the requested entry is either
585 * "true" or "false" (ignoring case) then that value is returned,
586 * otherwise the given default boolean value is returned.
587 *
588 * @exception IllegalArgumentException if key is larger then 80 characters
589 * @exception IllegalStateException if this node has been removed
590 * @exception NullPointerException if key is null
591 */
592 public boolean getBoolean(String key, boolean defaultVal) {
593 String value = get(key, null);
594
595 if ("true".equalsIgnoreCase(value))
596 return true;
597
598 if ("false".equalsIgnoreCase(value))
599 return false;
600
601 return defaultVal;
602 }
603
604 /**
605 * Convenience method for getting the given entry as a byte array.
606 * When the string representation of the requested entry is a valid
607 * Base64 encoded string (without any other characters, such as newlines)
608 * then the decoded Base64 string is returned as byte array,
609 * otherwise the given default byte array value is returned.
610 *
611 * @exception IllegalArgumentException if key is larger then 80 characters
612 * @exception IllegalStateException if this node has been removed
613 * @exception NullPointerException if key is null
614 */
615 public byte[] getByteArray(String key, byte[] defaultVal) {
616 String value = get(key, null);
617
618 byte[] b = null;
619 if (value != null) {
620 b = decode64(value);
621 }
622
623 if (b != null)
624 return b;
625 else
626 return defaultVal;
627 }
628
629 /**
630 * Helper method for decoding a Base64 string as an byte array.
631 * Returns null on encoding error. This method does not allow any other
632 * characters present in the string then the 65 special base64 chars.
633 */
634 private static byte[] decode64(String s) {
635 ByteArrayOutputStream bs = new ByteArrayOutputStream((s.length()/4)*3);
636 char[] c = new char[s.length()];
637 s.getChars(0, s.length(), c, 0);
638
639 // Convert from base64 chars
640 int endchar = -1;
641 for(int j = 0; j < c.length && endchar == -1; j++) {
642 if (c[j] >= 'A' && c[j] <= 'Z') {
643 c[j] -= 'A';
644 } else if (c[j] >= 'a' && c[j] <= 'z') {
645 c[j] = (char) (c[j] + 26 - 'a');
646 } else if (c[j] >= '0' && c[j] <= '9') {
647 c[j] = (char) (c[j] + 52 - '0');
648 } else if (c[j] == '+') {
649 c[j] = 62;
650 } else if (c[j] == '/') {
651 c[j] = 63;
652 } else if (c[j] == '=') {
653 endchar = j;
654 } else {
655 return null; // encoding exception
656 }
657 }
658
659 int remaining = endchar == -1 ? c.length : endchar;
660 int i = 0;
661 while (remaining > 0) {
662 // Four input chars (6 bits) are decoded as three bytes as
663 // 000000 001111 111122 222222
664
665 byte b0 = (byte) (c[i] << 2);
666 if (remaining >= 2) {
667 b0 += (c[i+1] & 0x30) >> 4;
668 }
669 bs.write(b0);
670
671 if (remaining >= 3) {
672 byte b1 = (byte) ((c[i+1] & 0x0F) << 4);
673 b1 += (byte) ((c[i+2] & 0x3C) >> 2);
674 bs.write(b1);
675 }
676
677 if (remaining >= 4) {
678 byte b2 = (byte) ((c[i+2] & 0x03) << 6);
679 b2 += c[i+3];
680 bs.write(b2);
681 }
682
683 i += 4;
684 remaining -= 4;
685 }
686
687 return bs.toByteArray();
688 }
689
690 /**
691 * Convenience method for getting the given entry as a double.
692 * When the string representation of the requested entry can be decoded
693 * with <code>Double.parseDouble()</code> then that double is returned,
694 * otherwise the given default double value is returned.
695 *
696 * @exception IllegalArgumentException if key is larger then 80 characters
697 * @exception IllegalStateException if this node has been removed
698 * @exception NullPointerException if key is null
699 */
700 public double getDouble(String key, double defaultVal) {
701 String value = get(key, null);
702
703 if (value != null) {
704 try {
705 return Double.parseDouble(value);
706 } catch (NumberFormatException nfe) { /* ignore */ }
707 }
708
709 return defaultVal;
710 }
711
712 /**
713 * Convenience method for getting the given entry as a float.
714 * When the string representation of the requested entry can be decoded
715 * with <code>Float.parseFloat()</code> then that float is returned,
716 * otherwise the given default float value is returned.
717 *
718 * @exception IllegalArgumentException if key is larger then 80 characters
719 * @exception IllegalStateException if this node has been removed
720 * @exception NullPointerException if key is null
721 */
722 public float getFloat(String key, float defaultVal) {
723 String value = get(key, null);
724
725 if (value != null) {
726 try {
727 return Float.parseFloat(value);
728 } catch (NumberFormatException nfe) { /* ignore */ }
729 }
730
731 return defaultVal;
732 }
733
734 /**
735 * Convenience method for getting the given entry as an integer.
736 * When the string representation of the requested entry can be decoded
737 * with <code>Integer.parseInt()</code> then that integer is returned,
738 * otherwise the given default integer value is returned.
739 *
740 * @exception IllegalArgumentException if key is larger then 80 characters
741 * @exception IllegalStateException if this node has been removed
742 * @exception NullPointerException if key is null
743 */
744 public int getInt(String key, int defaultVal) {
745 String value = get(key, null);
746
747 if (value != null) {
748 try {
749 return Integer.parseInt(value);
750 } catch (NumberFormatException nfe) { /* ignore */ }
751 }
752
753 return defaultVal;
754 }
755
756 /**
757 * Convenience method for getting the given entry as a long.
758 * When the string representation of the requested entry can be decoded
759 * with <code>Long.parseLong()</code> then that long is returned,
760 * otherwise the given default long value is returned.
761 *
762 * @exception IllegalArgumentException if key is larger then 80 characters
763 * @exception IllegalStateException if this node has been removed
764 * @exception NullPointerException if key is null
765 */
766 public long getLong(String key, long defaultVal) {
767 String value = get(key, null);
768
769 if (value != null) {
770 try {
771 return Long.parseLong(value);
772 } catch (NumberFormatException nfe) { /* ignore */ }
773 }
774
775 return defaultVal;
776 }
777
778 /**
779 * Sets the value of the given preferences entry for this node.
780 * Key and value cannot be null, the key cannot exceed 80 characters
781 * and the value cannot exceed 8192 characters.
782 * <p>
783 * The result will be immediately visible in this VM, but may not be
784 * immediately written to the backing store.
785 * <p>
786 * Checks that key and value are valid, locks this node, and checks that
787 * the node has not been removed. Then it calls <code>putSpi()</code>.
788 *
789 * @exception NullPointerException if either key or value are null
790 * @exception IllegalArgumentException if either key or value are to large
791 * @exception IllegalStateException when this node has been removed
792 */
793 public void put(String key, String value) {
794 if (key.length() > MAX_KEY_LENGTH
795 || value.length() > MAX_VALUE_LENGTH)
796 throw new IllegalArgumentException("key ("
797 + key.length() + ")"
798 + " or value ("
799 + value.length() + ")"
800 + " to large");
801 synchronized(lock) {
802 if (isRemoved())
803 throw new IllegalStateException("Node removed");
804
805 putSpi(key, value);
806
807 if (preferenceListeners != null)
808 fire(new PreferenceChangeEvent(this, key, value));
809 }
810
811 }
812
813 /**
814 * Convenience method for setting the given entry as a boolean.
815 * The boolean is converted with <code>Boolean.toString(value)</code>
816 * and then stored in the preference entry as that string.
817 *
818 * @exception NullPointerException if key is null
819 * @exception IllegalArgumentException if the key length is to large
820 * @exception IllegalStateException when this node has been removed
821 */
822 public void putBoolean(String key, boolean value) {
823 put(key, Boolean.toString(value));
824 }
825
826 /**
827 * Convenience method for setting the given entry as an array of bytes.
828 * The byte array is converted to a Base64 encoded string
829 * and then stored in the preference entry as that string.
830 * <p>
831 * Note that a byte array encoded as a Base64 string will be about 1.3
832 * times larger then the original length of the byte array, which means
833 * that the byte array may not be larger about 6 KB.
834 *
835 * @exception NullPointerException if either key or value are null
836 * @exception IllegalArgumentException if either key or value are to large
837 * @exception IllegalStateException when this node has been removed
838 */
839 public void putByteArray(String key, byte[] value) {
840 put(key, encode64(value));
841 }
842
843 /**
844 * Helper method for encoding an array of bytes as a Base64 String.
845 */
846 private static String encode64(byte[] b) {
847 CPStringBuilder sb = new CPStringBuilder((b.length/3)*4);
848
849 int i = 0;
850 int remaining = b.length;
851 char c[] = new char[4];
852 while (remaining > 0) {
853 // Three input bytes are encoded as four chars (6 bits) as
854 // 00000011 11112222 22333333
855
856 c[0] = (char) ((b[i] & 0xFC) >> 2);
857 c[1] = (char) ((b[i] & 0x03) << 4);
858 if (remaining >= 2) {
859 c[1] += (char) ((b[i+1] & 0xF0) >> 4);
860 c[2] = (char) ((b[i+1] & 0x0F) << 2);
861 if (remaining >= 3) {
862 c[2] += (char) ((b[i+2] & 0xC0) >> 6);
863 c[3] = (char) (b[i+2] & 0x3F);
864 } else {
865 c[3] = 64;
866 }
867 } else {
868 c[2] = 64;
869 c[3] = 64;
870 }
871
872 // Convert to base64 chars
873 for(int j = 0; j < 4; j++) {
874 if (c[j] < 26) {
875 c[j] += 'A';
876 } else if (c[j] < 52) {
877 c[j] = (char) (c[j] - 26 + 'a');
878 } else if (c[j] < 62) {
879 c[j] = (char) (c[j] - 52 + '0');
880 } else if (c[j] == 62) {
881 c[j] = '+';
882 } else if (c[j] == 63) {
883 c[j] = '/';
884 } else {
885 c[j] = '=';
886 }
887 }
888
889 sb.append(c);
890 i += 3;
891 remaining -= 3;
892 }
893
894 return sb.toString();
895 }
896
897 /**
898 * Convenience method for setting the given entry as a double.
899 * The double is converted with <code>Double.toString(double)</code>
900 * and then stored in the preference entry as that string.
901 *
902 * @exception NullPointerException if the key is null
903 * @exception IllegalArgumentException if the key length is to large
904 * @exception IllegalStateException when this node has been removed
905 */
906 public void putDouble(String key, double value) {
907 put(key, Double.toString(value));
908 }
909
910 /**
911 * Convenience method for setting the given entry as a float.
912 * The float is converted with <code>Float.toString(float)</code>
913 * and then stored in the preference entry as that string.
914 *
915 * @exception NullPointerException if the key is null
916 * @exception IllegalArgumentException if the key length is to large
917 * @exception IllegalStateException when this node has been removed
918 */
919 public void putFloat(String key, float value) {
920 put(key, Float.toString(value));
921 }
922
923 /**
924 * Convenience method for setting the given entry as an integer.
925 * The integer is converted with <code>Integer.toString(int)</code>
926 * and then stored in the preference entry as that string.
927 *
928 * @exception NullPointerException if the key is null
929 * @exception IllegalArgumentException if the key length is to large
930 * @exception IllegalStateException when this node has been removed
931 */
932 public void putInt(String key, int value) {
933 put(key, Integer.toString(value));
934 }
935
936 /**
937 * Convenience method for setting the given entry as a long.
938 * The long is converted with <code>Long.toString(long)</code>
939 * and then stored in the preference entry as that string.
940 *
941 * @exception NullPointerException if the key is null
942 * @exception IllegalArgumentException if the key length is to large
943 * @exception IllegalStateException when this node has been removed
944 */
945 public void putLong(String key, long value) {
946 put(key, Long.toString(value));
947 }
948
949 /**
950 * Removes the preferences entry from this preferences node.
951 * <p>
952 * The result will be immediately visible in this VM, but may not be
953 * immediately written to the backing store.
954 * <p>
955 * This implementation checks that the key is not larger then 80
956 * characters, gets the lock of this node, checks that the node has
957 * not been removed and calls <code>removeSpi</code> with the given key.
958 *
959 * @exception NullPointerException if the key is null
960 * @exception IllegalArgumentException if the key length is to large
961 * @exception IllegalStateException when this node has been removed
962 */
963 public void remove(String key) {
964 if (key.length() > MAX_KEY_LENGTH)
965 throw new IllegalArgumentException(key);
966
967 synchronized(lock) {
968 if (isRemoved())
969 throw new IllegalStateException("Node removed");
970
971 removeSpi(key);
972
973 if (preferenceListeners != null)
974 fire(new PreferenceChangeEvent(this, key, null));
975 }
976 }
977
978 /**
979 * Removes all entries from this preferences node. May need access to the
980 * backing store to get and clear all entries.
981 * <p>
982 * The result will be immediately visible in this VM, but may not be
983 * immediatly written to the backing store.
984 * <p>
985 * This implementation locks this node, checks that the node has not been
986 * removed and calls <code>keys()</code> to get a complete array of keys
987 * for this node. For every key found <code>removeSpi()</code> is called.
988 *
989 * @exception BackingStoreException when the backing store cannot be
990 * reached
991 * @exception IllegalStateException if this node has been removed
992 */
993 public void clear() throws BackingStoreException {
994 synchronized(lock) {
995 if (isRemoved())
996 throw new IllegalStateException("Node Removed");
997
998 String[] keys = keys();
999 for (int i = 0; i < keys.length; i++) {
1000 removeSpi(keys[i]);
1001 }
1002 }
1003 }
1004
1005 /**
1006 * Writes all preference changes on this and any subnode that have not
1007 * yet been written to the backing store. This has no effect on the
1008 * preference entries in this VM, but it makes sure that all changes
1009 * are visible to other programs (other VMs might need to call the
1010 * <code>sync()</code> method to actually see the changes to the backing
1011 * store.
1012 * <p>
1013 * Locks this node, calls the <code>flushSpi()</code> method, gets all
1014 * the (cached - already existing in this VM) subnodes and then calls
1015 * <code>flushSpi()</code> on every subnode with this node unlocked and
1016 * only that particular subnode locked.
1017 *
1018 * @exception BackingStoreException when the backing store cannot be
1019 * reached
1020 */
1021 public void flush() throws BackingStoreException {
1022 flushNode(false);
1023 }
1024
1025 /**
1026 * Writes and reads all preference changes to and from this and any
1027 * subnodes. This makes sure that all local changes are written to the
1028 * backing store and that all changes to the backing store are visible
1029 * in this preference node (and all subnodes).
1030 * <p>
1031 * Checks that this node is not removed, locks this node, calls the
1032 * <code>syncSpi()</code> method, gets all the subnodes and then calls
1033 * <code>syncSpi()</code> on every subnode with this node unlocked and
1034 * only that particular subnode locked.
1035 *
1036 * @exception BackingStoreException when the backing store cannot be
1037 * reached
1038 * @exception IllegalStateException if this node has been removed
1039 */
1040 public void sync() throws BackingStoreException {
1041 flushNode(true);
1042 }
1043
1044
1045 /**
1046 * Private helper method that locks this node and calls either
1047 * <code>flushSpi()</code> if <code>sync</code> is false, or
1048 * <code>flushSpi()</code> if <code>sync</code> is true. Then it gets all
1049 * the currently cached subnodes. For every subnode it calls this method
1050 * recursively with this node no longer locked.
1051 * <p>
1052 * Called by either <code>flush()</code> or <code>sync()</code>
1053 */
1054 private void flushNode(boolean sync) throws BackingStoreException {
1055 String[] keys = null;
1056 synchronized(lock) {
1057 if (sync) {
1058 syncSpi();
1059 } else {
1060 flushSpi();
1061 }
1062 keys = (String[]) childCache.keySet().toArray(new String[]{});
1063 }
1064
1065 if (keys != null) {
1066 for (int i = 0; i < keys.length; i++) {
1067 // Have to lock this node again to access the childCache
1068 AbstractPreferences subNode;
1069 synchronized(lock) {
1070 subNode = (AbstractPreferences) childCache.get(keys[i]);
1071 }
1072
1073 // The child could already have been removed from the cache
1074 if (subNode != null) {
1075 subNode.flushNode(sync);
1076 }
1077 }
1078 }
1079 }
1080
1081 /**
1082 * Removes this and all subnodes from the backing store and clears all
1083 * entries. After removal this instance will not be useable (except for
1084 * a few methods that don't throw a <code>InvalidStateException</code>),
1085 * even when a new node with the same path name is created this instance
1086 * will not be usable again.
1087 * <p>
1088 * Checks that this is not a root node. If not it locks the parent node,
1089 * then locks this node and checks that the node has not yet been removed.
1090 * Then it makes sure that all subnodes of this node are in the child cache,
1091 * by calling <code>childSpi()</code> on any children not yet in the cache.
1092 * Then for all children it locks the subnode and removes it. After all
1093 * subnodes have been purged the child cache is cleared, this nodes removed
1094 * flag is set and any listeners are called. Finally this node is removed
1095 * from the child cache of the parent node.
1096 *
1097 * @exception BackingStoreException when the backing store cannot be
1098 * reached
1099 * @exception IllegalStateException if this node has already been removed
1100 * @exception UnsupportedOperationException if this is a root node
1101 */
1102 public void removeNode() throws BackingStoreException {
1103 // Check if it is a root node
1104 if (parent == null)
1105 throw new UnsupportedOperationException("Cannot remove root node");
1106
1107 synchronized (parent.lock) {
1108 synchronized(this.lock) {
1109 if (isRemoved())
1110 throw new IllegalStateException("Node Removed");
1111
1112 purge();
1113 }
1114 parent.childCache.remove(name);
1115 }
1116 }
1117
1118 /**
1119 * Private helper method used to completely remove this node.
1120 * Called by <code>removeNode</code> with the parent node and this node
1121 * locked.
1122 * <p>
1123 * Makes sure that all subnodes of this node are in the child cache,
1124 * by calling <code>childSpi()</code> on any children not yet in the
1125 * cache. Then for all children it locks the subnode and calls this method
1126 * on that node. After all subnodes have been purged the child cache is
1127 * cleared, this nodes removed flag is set and any listeners are called.
1128 */
1129 private void purge() throws BackingStoreException
1130 {
1131 // Make sure all children have an AbstractPreferences node in cache
1132 String children[] = childrenNamesSpi();
1133 for (int i = 0; i < children.length; i++) {
1134 if (childCache.get(children[i]) == null)
1135 childCache.put(children[i], childSpi(children[i]));
1136 }
1137
1138 // purge all children
1139 Iterator i = childCache.values().iterator();
1140 while (i.hasNext()) {
1141 AbstractPreferences node = (AbstractPreferences) i.next();
1142 synchronized(node.lock) {
1143 node.purge();
1144 }
1145 }
1146
1147 // Cache is empty now
1148 childCache.clear();
1149
1150 // remove this node
1151 removeNodeSpi();
1152 removed = true;
1153
1154 if (nodeListeners != null)
1155 fire(new NodeChangeEvent(parent, this), false);
1156 }
1157
1158 // listener methods
1159
1160 /**
1161 * Add a listener which is notified when a sub-node of this node
1162 * is added or removed.
1163 * @param listener the listener to add
1164 */
1165 public void addNodeChangeListener(NodeChangeListener listener)
1166 {
1167 synchronized (lock)
1168 {
1169 if (isRemoved())
1170 throw new IllegalStateException("node has been removed");
1171 if (listener == null)
1172 throw new NullPointerException("listener is null");
1173 if (nodeListeners == null)
1174 nodeListeners = new ArrayList<NodeChangeListener>();
1175 nodeListeners.add(listener);
1176 }
1177 }
1178
1179 /**
1180 * Add a listener which is notified when a value in this node
1181 * is added, changed, or removed.
1182 * @param listener the listener to add
1183 */
1184 public void addPreferenceChangeListener(PreferenceChangeListener listener)
1185 {
1186 synchronized (lock)
1187 {
1188 if (isRemoved())
1189 throw new IllegalStateException("node has been removed");
1190 if (listener == null)
1191 throw new NullPointerException("listener is null");
1192 if (preferenceListeners == null)
1193 preferenceListeners = new ArrayList<PreferenceChangeListener>();
1194 preferenceListeners.add(listener);
1195 }
1196 }
1197
1198 /**
1199 * Remove the indicated node change listener from the list of
1200 * listeners to notify.
1201 * @param listener the listener to remove
1202 */
1203 public void removeNodeChangeListener(NodeChangeListener listener)
1204 {
1205 synchronized (lock)
1206 {
1207 if (isRemoved())
1208 throw new IllegalStateException("node has been removed");
1209 if (listener == null)
1210 throw new NullPointerException("listener is null");
1211 if (nodeListeners != null)
1212 nodeListeners.remove(listener);
1213 }
1214 }
1215
1216 /**
1217 * Remove the indicated preference change listener from the list of
1218 * listeners to notify.
1219 * @param listener the listener to remove
1220 */
1221 public void removePreferenceChangeListener (PreferenceChangeListener listener)
1222 {
1223 synchronized (lock)
1224 {
1225 if (isRemoved())
1226 throw new IllegalStateException("node has been removed");
1227 if (listener == null)
1228 throw new NullPointerException("listener is null");
1229 if (preferenceListeners != null)
1230 preferenceListeners.remove(listener);
1231 }
1232 }
1233
1234 /**
1235 * Send a preference change event to all listeners. Note that
1236 * the caller is responsible for holding the node's lock, and
1237 * for checking that the list of listeners is not null.
1238 * @param event the event to send
1239 */
1240 private void fire(final PreferenceChangeEvent event)
1241 {
1242 for (final PreferenceChangeListener listener : preferenceListeners)
1243 {
1244 Runnable dispatcher = new Runnable() {
1245 public void run()
1246 {
1247 listener.preferenceChange(event);
1248 }
1249 };
1250
1251 Executor executor =
1252 Executors.newSingleThreadExecutor(new DefaultDaemonThreadFactory());
1253 executor.execute(dispatcher);
1254 }
1255 }
1256
1257 /**
1258 * Send a node change event to all listeners. Note that
1259 * the caller is responsible for holding the node's lock, and
1260 * for checking that the list of listeners is not null.
1261 * @param event the event to send
1262 */
1263 private void fire(final NodeChangeEvent event, final boolean added)
1264 {
1265 for (final NodeChangeListener listener : nodeListeners)
1266 {
1267 Runnable dispatcher = new Runnable() {
1268 public void run()
1269 {
1270 if (added)
1271 listener.childAdded(event);
1272 else
1273 listener.childRemoved(event);
1274 }
1275 };
1276
1277 Executor executor =
1278 Executors.newSingleThreadExecutor(new DefaultDaemonThreadFactory());
1279 executor.execute(dispatcher);
1280 }
1281 }
1282
1283 // abstract spi methods
1284
1285 /**
1286 * Returns the names of the sub nodes of this preference node.
1287 * This method only has to return any not yet cached child names,
1288 * but may return all names if that is easier. It must not return
1289 * null when there are no children, it has to return an empty array
1290 * in that case. Since this method must consult the backing store to
1291 * get all the sub node names it may throw a BackingStoreException.
1292 * <p>
1293 * Called by <code>childrenNames()</code> with this node locked.
1294 */
1295 protected abstract String[] childrenNamesSpi() throws BackingStoreException;
1296
1297 /**
1298 * Returns a child note with the given name.
1299 * This method is called by the <code>node()</code> method (indirectly
1300 * through the <code>getNode()</code> helper method) with this node locked
1301 * if a sub node with this name does not already exist in the child cache.
1302 * If the child node did not aleady exist in the backing store the boolean
1303 * field <code>newNode</code> of the returned node should be set.
1304 * <p>
1305 * Note that this method should even return a non-null child node if the
1306 * backing store is not available since it may not throw a
1307 * <code>BackingStoreException</code>.
1308 */
1309 protected abstract AbstractPreferences childSpi(String name);
1310
1311 /**
1312 * Returns an (possibly empty) array with all the keys of the preference
1313 * entries of this node.
1314 * <p>
1315 * Called by <code>keys()</code> with this node locked if this node has
1316 * not been removed. May throw an exception when the backing store cannot
1317 * be accessed.
1318 *
1319 * @exception BackingStoreException when the backing store cannot be
1320 * reached
1321 */
1322 protected abstract String[] keysSpi() throws BackingStoreException;
1323
1324 /**
1325 * Returns the value associated with the key in this preferences node or
1326 * null when the key does not exist in this preferences node.
1327 * <p>
1328 * Called by <code>key()</code> with this node locked after checking that
1329 * key is valid, not null and that the node has not been removed.
1330 * <code>key()</code> will catch any exceptions that this method throws.
1331 */
1332 protected abstract String getSpi(String key);
1333
1334 /**
1335 * Sets the value of the given preferences entry for this node.
1336 * The implementation is not required to propagate the change to the
1337 * backing store immediately. It may not throw an exception when it tries
1338 * to write to the backing store and that operation fails, the failure
1339 * should be registered so a later invocation of <code>flush()</code>
1340 * or <code>sync()</code> can signal the failure.
1341 * <p>
1342 * Called by <code>put()</code> with this node locked after checking that
1343 * key and value are valid and non-null.
1344 */
1345 protected abstract void putSpi(String key, String value);
1346
1347 /**
1348 * Removes the given key entry from this preferences node.
1349 * The implementation is not required to propagate the change to the
1350 * backing store immediately. It may not throw an exception when it tries
1351 * to write to the backing store and that operation fails, the failure
1352 * should be registered so a later invocation of <code>flush()</code>
1353 * or <code>sync()</code> can signal the failure.
1354 * <p>
1355 * Called by <code>remove()</code> with this node locked after checking
1356 * that the key is valid and non-null.
1357 */
1358 protected abstract void removeSpi(String key);
1359
1360 /**
1361 * Writes all entries of this preferences node that have not yet been
1362 * written to the backing store and possibly creates this node in the
1363 * backing store, if it does not yet exist. Should only write changes to
1364 * this node and not write changes to any subnodes.
1365 * Note that the node can be already removed in this VM. To check if
1366 * that is the case the implementation can call <code>isRemoved()</code>.
1367 * <p>
1368 * Called (indirectly) by <code>flush()</code> with this node locked.
1369 */
1370 protected abstract void flushSpi() throws BackingStoreException;
1371
1372 /**
1373 * Writes all entries of this preferences node that have not yet been
1374 * written to the backing store and reads any entries that have changed
1375 * in the backing store but that are not yet visible in this VM.
1376 * Should only sync this node and not change any of the subnodes.
1377 * Note that the node can be already removed in this VM. To check if
1378 * that is the case the implementation can call <code>isRemoved()</code>.
1379 * <p>
1380 * Called (indirectly) by <code>sync()</code> with this node locked.
1381 */
1382 protected abstract void syncSpi() throws BackingStoreException;
1383
1384 /**
1385 * Clears this node from this VM and removes it from the backing store.
1386 * After this method has been called the node is marked as removed.
1387 * <p>
1388 * Called (indirectly) by <code>removeNode()</code> with this node locked
1389 * after all the sub nodes of this node have already been removed.
1390 */
1391 protected abstract void removeNodeSpi() throws BackingStoreException;
1392 }