Source for java.awt.AWTKeyStroke

   1: /* AWTKeyStroke.java -- an immutable key stroke
   2:    Copyright (C) 2002, 2004, 2005, 2006 Free Software Foundation
   3: 
   4: This file is part of GNU Classpath.
   5: 
   6: GNU Classpath is free software; you can redistribute it and/or modify
   7: it under the terms of the GNU General Public License as published by
   8: the Free Software Foundation; either version 2, or (at your option)
   9: any later version.
  10: 
  11: GNU Classpath is distributed in the hope that it will be useful, but
  12: WITHOUT ANY WARRANTY; without even the implied warranty of
  13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14: General Public License for more details.
  15: 
  16: You should have received a copy of the GNU General Public License
  17: along with GNU Classpath; see the file COPYING.  If not, write to the
  18: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19: 02110-1301 USA.
  20: 
  21: Linking this library statically or dynamically with other modules is
  22: making a combined work based on this library.  Thus, the terms and
  23: conditions of the GNU General Public License cover the whole
  24: combination.
  25: 
  26: As a special exception, the copyright holders of this library give you
  27: permission to link this library with independent modules to produce an
  28: executable, regardless of the license terms of these independent
  29: modules, and to copy and distribute the resulting executable under
  30: terms of your choice, provided that you also meet, for each linked
  31: independent module, the terms and conditions of the license of that
  32: module.  An independent module is a module which is not derived from
  33: or based on this library.  If you modify this library, you may extend
  34: this exception to your version of the library, but you are not
  35: obligated to do so.  If you do not wish to do so, delete this
  36: exception statement from your version. */
  37: 
  38: 
  39: package java.awt;
  40: 
  41: import java.awt.event.InputEvent;
  42: import java.awt.event.KeyEvent;
  43: import java.io.ObjectStreamException;
  44: import java.io.Serializable;
  45: import java.lang.reflect.Constructor;
  46: import java.lang.reflect.Field;
  47: import java.lang.reflect.InvocationTargetException;
  48: import java.security.AccessController;
  49: import java.security.PrivilegedAction;
  50: import java.security.PrivilegedActionException;
  51: import java.security.PrivilegedExceptionAction;
  52: import java.util.HashMap;
  53: import java.util.LinkedHashMap;
  54: import java.util.Map;
  55: import java.util.StringTokenizer;
  56: 
  57: /**
  58:  * This class mirrors KeyEvents, representing both low-level key presses and
  59:  * key releases, and high level key typed inputs. However, this class forms
  60:  * immutable strokes, and can be efficiently reused via the factory methods
  61:  * for creating them.
  62:  *
  63:  * <p>For backwards compatibility with Swing, this supports a way to build
  64:  * instances of a subclass, using reflection, provided the subclass has a
  65:  * no-arg constructor (of any accessibility).
  66:  *
  67:  * @author Eric Blake (ebb9@email.byu.edu)
  68:  * @author Andrew John Hughes (gnu_andrew@member.fsf.org)
  69:  * @see #getAWTKeyStroke(char)
  70:  * @since 1.4
  71:  * @status updated to 1.4
  72:  */
  73: public class AWTKeyStroke implements Serializable
  74: {
  75:   /**
  76:    * Compatible with JDK 1.4+.
  77:    */
  78:   private static final long serialVersionUID = -6430539691155161871L;
  79: 
  80:   /** The mask for modifiers. */
  81:   private static final int MODIFIERS_MASK = 0x3fef;
  82: 
  83:   /**
  84:    * The cache of recently created keystrokes. This maps KeyStrokes to
  85:    * KeyStrokes in a cache which removes the least recently accessed entry,
  86:    * under the assumption that garbage collection of a new keystroke is
  87:    * easy when we find the old one that it matches in the cache.
  88:    */
  89:   private static final LinkedHashMap<AWTKeyStroke,AWTKeyStroke> cache =
  90:     new LinkedHashMap<AWTKeyStroke,AWTKeyStroke>(11, 0.75f, true)
  91:   {
  92:     /** The largest the keystroke cache can grow. */
  93:     private static final int MAX_CACHE_SIZE = 2048;
  94: 
  95:     /** Prune stale entries. */
  96:     protected boolean removeEldestEntry(Entry<AWTKeyStroke,AWTKeyStroke>
  97:                     eldest)
  98:     {
  99:       return size() > MAX_CACHE_SIZE;
 100:     }
 101:   };
 102: 
 103:   /** The most recently generated keystroke, or null. */
 104:   private static AWTKeyStroke recent;
 105: 
 106:   /**
 107:    * The no-arg constructor of a subclass, or null to use AWTKeyStroke. Note
 108:    * that this will be left accessible, to get around private access; but
 109:    * it should not be a security risk as it is highly unlikely that creating
 110:    * protected instances of the subclass via reflection will do much damage.
 111:    */
 112:   private static Constructor ctor;
 113: 
 114:   /**
 115:    * A table of keyCode names to values.  This is package-private to
 116:    * avoid an accessor method.
 117:    *
 118:    * @see #getAWTKeyStroke(String)
 119:    */
 120:   static final HashMap<String,Object> vktable = new HashMap<String,Object>();
 121:   static
 122:   {
 123:     // Using reflection saves the hassle of keeping this in sync with KeyEvent,
 124:     // at the price of an expensive initialization.
 125:     AccessController.doPrivileged(new PrivilegedAction()
 126:       {
 127:         public Object run()
 128:         {
 129:           Field[] fields = KeyEvent.class.getFields();
 130:           int i = fields.length;
 131:           try
 132:             {
 133:               while (--i >= 0)
 134:                 {
 135:                   Field f = fields[i];
 136:                   String name = f.getName();
 137:                   if (name.startsWith("VK_"))
 138:                     vktable.put(name.substring(3), f.get(null));
 139:                 }
 140:             }
 141:           catch (Exception e)
 142:             {
 143:               throw (Error) new InternalError().initCause(e);
 144:             }
 145:           return null;
 146:         }
 147:       });
 148:   }
 149: 
 150:   /**
 151:    * The typed character, or CHAR_UNDEFINED for key presses and releases.
 152:    *
 153:    * @serial the keyChar
 154:    */
 155:   private char keyChar;
 156: 
 157:   /**
 158:    * The virtual key code, or VK_UNDEFINED for key typed. Package visible for
 159:    * use by Component.
 160:    *
 161:    * @serial the keyCode
 162:    */
 163:   int keyCode;
 164: 
 165:   /**
 166:    * The modifiers in effect. To match Sun, this stores the old style masks
 167:    * for shift, control, alt, meta, and alt-graph (but not button1); as well
 168:    * as the new style of extended modifiers for all modifiers.
 169:    *
 170:    * @serial bitwise or of the *_DOWN_MASK modifiers
 171:    */
 172:   private int modifiers;
 173: 
 174:   /**
 175:    * True if this is a key release; should only be true if keyChar is
 176:    * CHAR_UNDEFINED.
 177:    *
 178:    * @serial true to distinguish key pressed from key released
 179:    */
 180:   private boolean onKeyRelease;
 181: 
 182:   /**
 183:    * Construct a keystroke with default values: it will be interpreted as a
 184:    * key typed event with an invalid character and no modifiers. Client code
 185:    * should use the factory methods instead.
 186:    *
 187:    * @see #getAWTKeyStroke(char)
 188:    * @see #getAWTKeyStroke(Character, int)
 189:    * @see #getAWTKeyStroke(int, int, boolean)
 190:    * @see #getAWTKeyStroke(int, int)
 191:    * @see #getAWTKeyStrokeForEvent(KeyEvent)
 192:    * @see #getAWTKeyStroke(String)
 193:    */
 194:   protected AWTKeyStroke()
 195:   {
 196:     keyChar = KeyEvent.CHAR_UNDEFINED;
 197:   }
 198: 
 199:   /**
 200:    * Construct a keystroke with the given values. Client code should use the
 201:    * factory methods instead.
 202:    *
 203:    * @param keyChar the character entered, if this is a key typed
 204:    * @param keyCode the key pressed or released, or VK_UNDEFINED for key typed
 205:    * @param modifiers the modifier keys for the keystroke, in old or new style
 206:    * @param onKeyRelease true if this is a key release instead of a press
 207:    * @see #getAWTKeyStroke(char)
 208:    * @see #getAWTKeyStroke(Character, int)
 209:    * @see #getAWTKeyStroke(int, int, boolean)
 210:    * @see #getAWTKeyStroke(int, int)
 211:    * @see #getAWTKeyStrokeForEvent(KeyEvent)
 212:    * @see #getAWTKeyStroke(String)
 213:    */
 214:   protected AWTKeyStroke(char keyChar, int keyCode, int modifiers,
 215:                          boolean onKeyRelease)
 216:   {
 217:     this.keyChar = keyChar;
 218:     this.keyCode = keyCode;
 219:     // No need to call extend(), as only trusted code calls this constructor.
 220:     this.modifiers = modifiers;
 221:     this.onKeyRelease = onKeyRelease;
 222:   }
 223: 
 224:   /**
 225:    * Registers a new subclass as being the type of keystrokes to generate in
 226:    * the factory methods. This operation flushes the cache of stored keystrokes
 227:    * if the class differs from the current one. The new class must be
 228:    * AWTKeyStroke or a subclass, and must have a no-arg constructor (which may
 229:    * be private).
 230:    *
 231:    * @param subclass the new runtime type of generated keystrokes
 232:    * @throws IllegalArgumentException subclass doesn't have no-arg constructor
 233:    * @throws ClassCastException subclass doesn't extend AWTKeyStroke
 234:    */
 235:   protected static void registerSubclass(final Class<?> subclass)
 236:   {
 237:     if (subclass == null)
 238:       throw new IllegalArgumentException();
 239:     if (subclass.equals(ctor == null ? AWTKeyStroke.class
 240:                         : ctor.getDeclaringClass()))
 241:       return;
 242:     if (subclass.equals(AWTKeyStroke.class))
 243:        {
 244:          cache.clear();
 245:          recent = null;
 246:          ctor = null;
 247:          return;
 248:        }
 249:     try
 250:       {
 251:         ctor = (Constructor) AccessController.doPrivileged
 252:           (new PrivilegedExceptionAction()
 253:             {
 254:               public Object run()
 255:                 throws NoSuchMethodException, InstantiationException,
 256:                        IllegalAccessException, InvocationTargetException
 257:               {
 258:                 Constructor<?> c =
 259:           subclass.getDeclaredConstructor((Class<?>[])null);
 260:                 c.setAccessible(true);
 261:                 // Create a new instance, to make sure that we can, and
 262:                 // to cause any ClassCastException.
 263:                 AWTKeyStroke dummy = (AWTKeyStroke) c.newInstance(null);
 264:                 return c;
 265:               }
 266:             });
 267:       }
 268:     catch (PrivilegedActionException e)
 269:       {
 270:         // e.getCause() will not ever be ClassCastException; that should
 271:         // escape on its own.
 272:         throw (RuntimeException)
 273:           new IllegalArgumentException().initCause(e.getCause());
 274:       }
 275:     cache.clear();
 276:     recent = null;
 277:   }
 278: 
 279:   /**
 280:    * Returns a keystroke representing a typed character.
 281:    *
 282:    * @param keyChar the typed character 
 283:    * @return the specified keystroke
 284:    */
 285:   public static AWTKeyStroke getAWTKeyStroke(char keyChar)
 286:   {
 287:     return getAWTKeyStroke(keyChar, KeyEvent.VK_UNDEFINED, 0, false);
 288:   }
 289: 
 290:   /**
 291:    * Returns a keystroke representing a typed character with the given
 292:    * modifiers. Note that keyChar is a <code>Character</code> instead of a
 293:    * <code>char</code> to avoid accidental ambiguity with
 294:    * <code>getAWTKeyStroke(int, int)</code>. The modifiers are the bitwise
 295:    * or of the masks found in {@link InputEvent}; the new style (*_DOWN_MASK)
 296:    * is preferred, but the old style will work.
 297:    *
 298:    * @param keyChar the typed character
 299:    * @param modifiers the modifiers, or 0
 300:    * @return the specified keystroke
 301:    * @throws IllegalArgumentException if keyChar is null
 302:    */
 303:   public static AWTKeyStroke getAWTKeyStroke(Character keyChar, int modifiers)
 304:   {
 305:     if (keyChar == null)
 306:       throw new IllegalArgumentException();
 307:     return getAWTKeyStroke(keyChar.charValue(), KeyEvent.VK_UNDEFINED,
 308:                            extend(modifiers), false);
 309:   }
 310: 
 311:   /**
 312:    * Returns a keystroke representing a pressed or released key event, with
 313:    * the given modifiers. The "virtual key" should be one of the VK_*
 314:    * constants in {@link KeyEvent}. The modifiers are the bitwise or of the
 315:    * masks found in {@link InputEvent}; the new style (*_DOWN_MASK) is
 316:    * preferred, but the old style will work.
 317:    *
 318:    * @param keyCode the virtual key
 319:    * @param modifiers the modifiers, or 0
 320:    * @param release true if this is a key release instead of a key press
 321:    * @return the specified keystroke
 322:    */
 323:   public static AWTKeyStroke getAWTKeyStroke(int keyCode, int modifiers,
 324:                                              boolean release)
 325:   {
 326:     return getAWTKeyStroke(KeyEvent.CHAR_UNDEFINED, keyCode,
 327:                            extend(modifiers), release);
 328:   }
 329: 
 330:   /**
 331:    * Returns a keystroke representing a pressed key event, with the given
 332:    * modifiers. The "virtual key" should be one of the VK_* constants in
 333:    * {@link KeyEvent}. The modifiers are the bitwise or of the masks found
 334:    * in {@link InputEvent}; the new style (*_DOWN_MASK) is preferred, but the
 335:    * old style will work.
 336:    *
 337:    * @param keyCode the virtual key
 338:    * @param modifiers the modifiers, or 0
 339:    * @return the specified keystroke
 340:    */
 341:   public static AWTKeyStroke getAWTKeyStroke(int keyCode, int modifiers)
 342:   {
 343:     return getAWTKeyStroke(KeyEvent.CHAR_UNDEFINED, keyCode,
 344:                            extend(modifiers), false);
 345:   }
 346: 
 347:   /**
 348:    * Returns a keystroke representing what caused the key event.
 349:    *
 350:    * @param event the key event to convert
 351:    * @return the specified keystroke, or null if the event is invalid
 352:    * @throws NullPointerException if event is null
 353:    */
 354:   public static AWTKeyStroke getAWTKeyStrokeForEvent(KeyEvent event)
 355:   {
 356:     switch (event.id)
 357:       {
 358:       case KeyEvent.KEY_TYPED:
 359:         return getAWTKeyStroke(event.getKeyChar(), KeyEvent.VK_UNDEFINED,
 360:                                extend(event.getModifiersEx()), false);
 361:       case KeyEvent.KEY_PRESSED:
 362:         return getAWTKeyStroke(KeyEvent.CHAR_UNDEFINED, event.getKeyCode(),
 363:                                extend(event.getModifiersEx()), false);
 364:       case KeyEvent.KEY_RELEASED:
 365:         return getAWTKeyStroke(KeyEvent.CHAR_UNDEFINED, event.getKeyCode(),
 366:                                extend(event.getModifiersEx()), true);
 367:       default:
 368:         return null;
 369:       }
 370:   }
 371: 
 372:   /**
 373:    * Parses a string and returns the keystroke that it represents. The syntax
 374:    * for keystrokes is listed below, with tokens separated by an arbitrary
 375:    * number of spaces:
 376:    * <pre>
 377:    * keyStroke := &lt;modifiers&gt;* ( &lt;typedID&gt; | &lt;codeID&gt; )
 378:    * modifiers := ( shift | control | ctrl | meta | alt
 379:    *                | button1 | button2 | button3 )
 380:    * typedID := typed &lt;single Unicode character&gt;
 381:    * codeID := ( pressed | released )? &lt;name&gt;
 382:    * name := &lt;the KeyEvent field name less the leading "VK_"&gt;
 383:    * </pre>
 384:    *
 385:    * <p>Note that the grammar is rather weak, and not all valid keystrokes
 386:    * can be generated in this manner (for example, a typed space, or anything
 387:    * with the alt-graph modifier!). The output of AWTKeyStroke.toString()
 388:    * will not meet the grammar. If pressed or released is not specified,
 389:    * pressed is assumed. Examples:<br>
 390:    * <code>
 391:    * "INSERT" =&gt; getAWTKeyStroke(KeyEvent.VK_INSERT, 0);<br>
 392:    * "control DELETE" =&gt;
 393:    *    getAWTKeyStroke(KeyEvent.VK_DELETE, InputEvent.CTRL_MASK);<br>
 394:    * "alt shift X" =&gt; getAWTKeyStroke(KeyEvent.VK_X,
 395:    *    InputEvent.ALT_MASK | InputEvent.SHIFT_MASK);<br>
 396:    * "alt shift released X" =&gt; getAWTKeyStroke(KeyEvent.VK_X,
 397:    *    InputEvent.ALT_MASK | InputEvent.SHIFT_MASK, true);<br>
 398:    * "typed a" =&gt; getAWTKeyStroke('a');
 399:    * </code>      
 400:    *
 401:    * @param s the string to parse
 402:    * @throws IllegalArgumentException if s is null or cannot be parsed
 403:    * @return the specified keystroke
 404:    */
 405:   public static AWTKeyStroke getAWTKeyStroke(String s)
 406:   {
 407:     if (s == null)
 408:       throw new IllegalArgumentException("null argument");
 409:     StringTokenizer t = new StringTokenizer(s, " ");
 410:     if (! t.hasMoreTokens())
 411:       throw new IllegalArgumentException("no tokens '" + s + "'");
 412:     int modifiers = 0;
 413:     boolean released = false;
 414:     String token = null;
 415:     do
 416:       {
 417:         token = t.nextToken();
 418:         if ("shift".equals(token))
 419:       {
 420:         modifiers |= KeyEvent.SHIFT_MASK;
 421:         modifiers |= KeyEvent.SHIFT_DOWN_MASK;
 422:       }
 423:         else if ("ctrl".equals(token) || "control".equals(token))
 424:       {
 425:         modifiers |= KeyEvent.CTRL_MASK;
 426:         modifiers |= KeyEvent.CTRL_DOWN_MASK;
 427:       }
 428:         else if ("meta".equals(token))
 429:       {
 430:         modifiers |= KeyEvent.META_MASK;
 431:         modifiers |= KeyEvent.META_DOWN_MASK;
 432:       }
 433:         else if ("alt".equals(token))
 434:       {
 435:         modifiers |= KeyEvent.ALT_MASK;
 436:         modifiers |= KeyEvent.ALT_DOWN_MASK;
 437:       }
 438:         else if ("button1".equals(token))
 439:           modifiers |= KeyEvent.BUTTON1_DOWN_MASK;
 440:         else if ("button2".equals(token))
 441:           modifiers |= KeyEvent.BUTTON2_DOWN_MASK;
 442:         else if ("button3".equals(token))
 443:           modifiers |= KeyEvent.BUTTON3_DOWN_MASK;
 444:         else if ("typed".equals(token))
 445:           {
 446:             if (t.hasMoreTokens())
 447:               {
 448:                 token = t.nextToken();
 449:                 if (! t.hasMoreTokens() && token.length() == 1)
 450:                   return getAWTKeyStroke(token.charAt(0),
 451:                                          KeyEvent.VK_UNDEFINED, modifiers,
 452:                                          false);
 453:               }
 454:             throw new IllegalArgumentException("Invalid 'typed' argument '"
 455:                                + s + "'");
 456:           }
 457:         else if ("pressed".equals(token))
 458:           {
 459:             if (t.hasMoreTokens())
 460:               token = t.nextToken();
 461:             break;
 462:           }
 463:         else if ("released".equals(token))
 464:           {
 465:             released = true;
 466:             if (t.hasMoreTokens())
 467:               token = t.nextToken();
 468:             break;
 469:           }
 470:         else
 471:           break;
 472:       }
 473:     while (t.hasMoreTokens());
 474:     // Now token contains the VK name we must parse.
 475:     Integer code = (Integer) vktable.get(token);
 476:     if (code == null)
 477:       throw new IllegalArgumentException("Unknown token '" + token
 478:                      + "' in '" + s + "'");
 479:     if (t.hasMoreTokens())
 480:       throw new IllegalArgumentException("Too many tokens: " + s);
 481:     return getAWTKeyStroke(KeyEvent.CHAR_UNDEFINED, code.intValue(),
 482:                            modifiers, released);
 483:   }
 484: 
 485:   /**
 486:    * Returns the character of this keystroke, if it was typed.
 487:    *
 488:    * @return the character value, or CHAR_UNDEFINED
 489:    * @see #getAWTKeyStroke(char)
 490:    */
 491:   public final char getKeyChar()
 492:   {
 493:     return keyChar;
 494:   }
 495: 
 496:   /**
 497:    * Returns the virtual key code of this keystroke, if it was pressed or
 498:    * released. This will be a VK_* constant from KeyEvent.
 499:    *
 500:    * @return the virtual key code value, or VK_UNDEFINED
 501:    * @see #getAWTKeyStroke(int, int)
 502:    */
 503:   public final int getKeyCode()
 504:   {
 505:     return keyCode;
 506:   }
 507: 
 508:   /**
 509:    * Returns the modifiers for this keystroke. This will be a bitwise or of
 510:    * constants from InputEvent; it includes the old style masks for shift,
 511:    * control, alt, meta, and alt-graph (but not button1); as well as the new
 512:    * style of extended modifiers for all modifiers.
 513:    *
 514:    * @return the modifiers
 515:    * @see #getAWTKeyStroke(Character, int)
 516:    * @see #getAWTKeyStroke(int, int)
 517:    */
 518:   public final int getModifiers()
 519:   {
 520:     return modifiers;
 521:   }
 522: 
 523:   /**
 524:    * Tests if this keystroke is a key release.
 525:    *
 526:    * @return true if this is a key release
 527:    * @see #getAWTKeyStroke(int, int, boolean)
 528:    */
 529:   public final boolean isOnKeyRelease()
 530:   {
 531:     return onKeyRelease;
 532:   }
 533: 
 534:   /**
 535:    * Returns the AWT event type of this keystroke. This is one of
 536:    * {@link KeyEvent#KEY_TYPED}, {@link KeyEvent#KEY_PRESSED}, or
 537:    * {@link KeyEvent#KEY_RELEASED}.
 538:    *
 539:    * @return the key event type
 540:    */
 541:   public final int getKeyEventType()
 542:   {
 543:     return keyCode == KeyEvent.VK_UNDEFINED ? KeyEvent.KEY_TYPED
 544:       : onKeyRelease ? KeyEvent.KEY_RELEASED : KeyEvent.KEY_PRESSED;
 545:   }
 546: 
 547:   /**
 548:    * Returns a hashcode for this key event. It is not documented, but appears
 549:    * to be: <code>(getKeyChar() + 1) * (getKeyCode() + 1)
 550:    * * (getModifiers() + 1) * 2 + (isOnKeyRelease() ? 1 : 2)</code>.
 551:    *
 552:    * @return the hashcode
 553:    */
 554:   public int hashCode()
 555:   {
 556:     return (keyChar + 1) * (keyCode + 1) * (modifiers + 1) * 2
 557:       + (onKeyRelease ? 1 : 2);
 558:   }
 559: 
 560:   /**
 561:    * Tests two keystrokes for equality.
 562:    *
 563:    * @param o the object to test
 564:    * @return true if it is equal
 565:    */
 566:   public final boolean equals(Object o)
 567:   {
 568:     if (! (o instanceof AWTKeyStroke))
 569:       return false;
 570:     AWTKeyStroke s = (AWTKeyStroke) o;
 571:     return this == o || (keyChar == s.keyChar && keyCode == s.keyCode
 572:                          && modifiers == s.modifiers
 573:                          && onKeyRelease == s.onKeyRelease);
 574:   }
 575: 
 576:   /**
 577:    * Returns a string representation of this keystroke. For typed keystrokes,
 578:    * this is <code>"keyChar " + KeyEvent.getKeyModifiersText(getModifiers())
 579:    + getKeyChar()</code>; for pressed and released keystrokes, this is
 580:    * <code>"keyCode " + KeyEvent.getKeyModifiersText(getModifiers())
 581:    * + KeyEvent.getKeyText(getKeyCode())
 582:    * + (isOnKeyRelease() ? "-R" : "-P")</code>.
 583:    *
 584:    * @return a string representation
 585:    */
 586:   public String toString()
 587:   {
 588:     if (keyCode == KeyEvent.VK_UNDEFINED)
 589:       return "keyChar " + KeyEvent.getKeyModifiersText(modifiers) + keyChar;
 590:     return "keyCode " + KeyEvent.getKeyModifiersText(modifiers)
 591:       + KeyEvent.getKeyText(keyCode) + (onKeyRelease ? "-R" : "-P");
 592:   }
 593: 
 594:   /**
 595:    * Returns a cached version of the deserialized keystroke, if available.
 596:    *
 597:    * @return a cached replacement
 598:    * @throws ObjectStreamException if something goes wrong
 599:    */
 600:   protected Object readResolve() throws ObjectStreamException
 601:   {
 602:     AWTKeyStroke s = cache.get(this);
 603:     if (s != null)
 604:       return s;
 605:     cache.put(this, this);
 606:     return this;
 607:   }
 608: 
 609:   /**
 610:    * Gets the appropriate keystroke, creating one if necessary.
 611:    *
 612:    * @param keyChar the keyChar
 613:    * @param keyCode the keyCode
 614:    * @param modifiers the modifiers
 615:    * @param release true for key release
 616:    * @return the specified keystroke
 617:    */
 618:   private static AWTKeyStroke getAWTKeyStroke(char keyChar, int keyCode,
 619:                                               int modifiers, boolean release)
 620:   {
 621:     // Check level 0 cache.
 622:     AWTKeyStroke stroke = recent; // Avoid thread races.
 623:     if (stroke != null && stroke.keyChar == keyChar
 624:         && stroke.keyCode == keyCode && stroke.modifiers == modifiers
 625:         && stroke.onKeyRelease == release)
 626:       return stroke;
 627:     // Create a new object, on the assumption that if it has a match in the
 628:     // cache, the VM can easily garbage collect it as it is temporary.
 629:     Constructor c = ctor; // Avoid thread races.
 630:     if (c == null)
 631:       stroke = new AWTKeyStroke(keyChar, keyCode, modifiers, release);
 632:     else
 633:       try
 634:         {
 635:           stroke = (AWTKeyStroke) c.newInstance(null);
 636:           stroke.keyChar = keyChar;
 637:           stroke.keyCode = keyCode;
 638:           stroke.modifiers = modifiers;
 639:           stroke.onKeyRelease = release;
 640:         }
 641:       catch (Exception e)
 642:         {
 643:           throw (Error) new InternalError().initCause(e);
 644:         }
 645:     // Check level 1 cache.
 646:     AWTKeyStroke cached = (AWTKeyStroke) cache.get(stroke);
 647:     if (cached == null)
 648:       cache.put(stroke, stroke);
 649:     else
 650:       stroke = cached;
 651:     return recent = stroke;
 652:   }
 653: 
 654:   /**
 655:    * Converts the modifiers to the appropriate format.
 656:    *
 657:    * @param mod the modifiers to convert
 658:    * @return the adjusted modifiers
 659:    */
 660:   private static int extend(int mod)
 661:   {
 662:     if ((mod & (KeyEvent.SHIFT_MASK | KeyEvent.SHIFT_DOWN_MASK)) != 0)
 663:       mod |= KeyEvent.SHIFT_MASK | KeyEvent.SHIFT_DOWN_MASK;
 664:     if ((mod & (KeyEvent.CTRL_MASK | KeyEvent.CTRL_DOWN_MASK)) != 0)
 665:       mod |= KeyEvent.CTRL_MASK | KeyEvent.CTRL_DOWN_MASK;
 666:     if ((mod & (KeyEvent.META_MASK | KeyEvent.META_DOWN_MASK)) != 0)
 667:       mod |= KeyEvent.META_MASK | KeyEvent.META_DOWN_MASK;
 668:     if ((mod & (KeyEvent.ALT_MASK | KeyEvent.ALT_DOWN_MASK)) != 0)
 669:       mod |= KeyEvent.ALT_MASK | KeyEvent.ALT_DOWN_MASK;
 670:     if ((mod & (KeyEvent.ALT_GRAPH_MASK | KeyEvent.ALT_GRAPH_DOWN_MASK)) != 0)
 671:       mod |= KeyEvent.ALT_GRAPH_MASK | KeyEvent.ALT_GRAPH_DOWN_MASK;
 672:     if ((mod & KeyEvent.BUTTON1_MASK) != 0)
 673:       mod |= KeyEvent.BUTTON1_DOWN_MASK;
 674:     return mod & MODIFIERS_MASK;
 675:   }
 676: } // class AWTKeyStroke