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| 1 | /* | ||
| 2 | * Copyright (c) 2000, 2009, Oracle and/or its affiliates. All rights reserved. | ||
| 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | ||
| 4 | * | ||
| 5 | * This code is free software; you can redistribute it and/or modify it | ||
| 6 | * under the terms of the GNU General Public License version 2 only, as | ||
| 7 | * published by the Free Software Foundation. Oracle designates this | ||
| 8 | * particular file as subject to the "Classpath" exception as provided | ||
| 9 | * by Oracle in the LICENSE file that accompanied this code. | ||
| 10 | * | ||
| 11 | * This code is distributed in the hope that it will be useful, but WITHOUT | ||
| 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | ||
| 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | ||
| 14 | * version 2 for more details (a copy is included in the LICENSE file that | ||
| 15 | * accompanied this code). | ||
| 16 | * | ||
| 17 | * You should have received a copy of the GNU General Public License version | ||
| 18 | * 2 along with this work; if not, write to the Free Software Foundation, | ||
| 19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | ||
| 20 | * | ||
| 21 | * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | ||
| 22 | * or visit www.oracle.com if you need additional information or have any | ||
| 23 | * questions. | ||
| 24 | */ | ||
| 25 | package java.beans; | ||
| 26 | |||
| 27 | import java.lang.reflect.InvocationHandler; | ||
| 28 | import java.lang.reflect.InvocationTargetException; | ||
| 29 | import java.lang.reflect.Proxy; | ||
| 30 | import java.lang.reflect.Method; | ||
| 31 | import java.security.AccessControlContext; | ||
| 32 | import java.security.AccessController; | ||
| 33 | import java.security.PrivilegedAction; | ||
| 34 | |||
| 35 | import sun.reflect.misc.MethodUtil; | ||
| 36 | |||
| 37 | /** | ||
| 38 | * The <code>EventHandler</code> class provides | ||
| 39 | * support for dynamically generating event listeners whose methods | ||
| 40 | * execute a simple statement involving an incoming event object | ||
| 41 | * and a target object. | ||
| 42 | * <p> | ||
| 43 | * The <code>EventHandler</code> class is intended to be used by interactive tools, such as | ||
| 44 | * application builders, that allow developers to make connections between | ||
| 45 | * beans. Typically connections are made from a user interface bean | ||
| 46 | * (the event <em>source</em>) | ||
| 47 | * to an application logic bean (the <em>target</em>). The most effective | ||
| 48 | * connections of this kind isolate the application logic from the user | ||
| 49 | * interface. For example, the <code>EventHandler</code> for a | ||
| 50 | * connection from a <code>JCheckBox</code> to a method | ||
| 51 | * that accepts a boolean value can deal with extracting the state | ||
| 52 | * of the check box and passing it directly to the method so that | ||
| 53 | * the method is isolated from the user interface layer. | ||
| 54 | * <p> | ||
| 55 | * Inner classes are another, more general way to handle events from | ||
| 56 | * user interfaces. The <code>EventHandler</code> class | ||
| 57 | * handles only a subset of what is possible using inner | ||
| 58 | * classes. However, <code>EventHandler</code> works better | ||
| 59 | * with the long-term persistence scheme than inner classes. | ||
| 60 | * Also, using <code>EventHandler</code> in large applications in | ||
| 61 | * which the same interface is implemented many times can | ||
| 62 | * reduce the disk and memory footprint of the application. | ||
| 63 | * <p> | ||
| 64 | * The reason that listeners created with <code>EventHandler</code> | ||
| 65 | * have such a small | ||
| 66 | * footprint is that the <code>Proxy</code> class, on which | ||
| 67 | * the <code>EventHandler</code> relies, shares implementations | ||
| 68 | * of identical | ||
| 69 | * interfaces. For example, if you use | ||
| 70 | * the <code>EventHandler</code> <code>create</code> methods to make | ||
| 71 | * all the <code>ActionListener</code>s in an application, | ||
| 72 | * all the action listeners will be instances of a single class | ||
| 73 | * (one created by the <code>Proxy</code> class). | ||
| 74 | * In general, listeners based on | ||
| 75 | * the <code>Proxy</code> class require one listener class | ||
| 76 | * to be created per <em>listener type</em> (interface), | ||
| 77 | * whereas the inner class | ||
| 78 | * approach requires one class to be created per <em>listener</em> | ||
| 79 | * (object that implements the interface). | ||
| 80 | * | ||
| 81 | * <p> | ||
| 82 | * You don't generally deal directly with <code>EventHandler</code> | ||
| 83 | * instances. | ||
| 84 | * Instead, you use one of the <code>EventHandler</code> | ||
| 85 | * <code>create</code> methods to create | ||
| 86 | * an object that implements a given listener interface. | ||
| 87 | * This listener object uses an <code>EventHandler</code> object | ||
| 88 | * behind the scenes to encapsulate information about the | ||
| 89 | * event, the object to be sent a message when the event occurs, | ||
| 90 | * the message (method) to be sent, and any argument | ||
| 91 | * to the method. | ||
| 92 | * The following section gives examples of how to create listener | ||
| 93 | * objects using the <code>create</code> methods. | ||
| 94 | * | ||
| 95 | * <h2>Examples of Using EventHandler</h2> | ||
| 96 | * | ||
| 97 | * The simplest use of <code>EventHandler</code> is to install | ||
| 98 | * a listener that calls a method on the target object with no arguments. | ||
| 99 | * In the following example we create an <code>ActionListener</code> | ||
| 100 | * that invokes the <code>toFront</code> method on an instance | ||
| 101 | * of <code>javax.swing.JFrame</code>. | ||
| 102 | * | ||
| 103 | * <blockquote> | ||
| 104 | *<pre> | ||
| 105 | *myButton.addActionListener( | ||
| 106 | * (ActionListener)EventHandler.create(ActionListener.class, frame, "toFront")); | ||
| 107 | *</pre> | ||
| 108 | * </blockquote> | ||
| 109 | * | ||
| 110 | * When <code>myButton</code> is pressed, the statement | ||
| 111 | * <code>frame.toFront()</code> will be executed. One could get | ||
| 112 | * the same effect, with some additional compile-time type safety, | ||
| 113 | * by defining a new implementation of the <code>ActionListener</code> | ||
| 114 | * interface and adding an instance of it to the button: | ||
| 115 | * | ||
| 116 | * <blockquote> | ||
| 117 | *<pre> | ||
| 118 | //Equivalent code using an inner class instead of EventHandler. | ||
| 119 | *myButton.addActionListener(new ActionListener() { | ||
| 120 | * public void actionPerformed(ActionEvent e) { | ||
| 121 | * frame.toFront(); | ||
| 122 | * } | ||
| 123 | *}); | ||
| 124 | *</pre> | ||
| 125 | * </blockquote> | ||
| 126 | * | ||
| 127 | * The next simplest use of <code>EventHandler</code> is | ||
| 128 | * to extract a property value from the first argument | ||
| 129 | * of the method in the listener interface (typically an event object) | ||
| 130 | * and use it to set the value of a property in the target object. | ||
| 131 | * In the following example we create an <code>ActionListener</code> that | ||
| 132 | * sets the <code>nextFocusableComponent</code> property of the target | ||
| 133 | * (myButton) object to the value of the "source" property of the event. | ||
| 134 | * | ||
| 135 | * <blockquote> | ||
| 136 | *<pre> | ||
| 137 | *EventHandler.create(ActionListener.class, myButton, "nextFocusableComponent", "source") | ||
| 138 | *</pre> | ||
| 139 | * </blockquote> | ||
| 140 | * | ||
| 141 | * This would correspond to the following inner class implementation: | ||
| 142 | * | ||
| 143 | * <blockquote> | ||
| 144 | *<pre> | ||
| 145 | //Equivalent code using an inner class instead of EventHandler. | ||
| 146 | *new ActionListener() { | ||
| 147 | * public void actionPerformed(ActionEvent e) { | ||
| 148 | * myButton.setNextFocusableComponent((Component)e.getSource()); | ||
| 149 | * } | ||
| 150 | *} | ||
| 151 | *</pre> | ||
| 152 | * </blockquote> | ||
| 153 | * | ||
| 154 | * It's also possible to create an <code>EventHandler</code> that | ||
| 155 | * just passes the incoming event object to the target's action. | ||
| 156 | * If the fourth <code>EventHandler.create</code> argument is | ||
| 157 | * an empty string, then the event is just passed along: | ||
| 158 | * | ||
| 159 | * <blockquote> | ||
| 160 | *<pre> | ||
| 161 | *EventHandler.create(ActionListener.class, target, "doActionEvent", "") | ||
| 162 | *</pre> | ||
| 163 | * </blockquote> | ||
| 164 | * | ||
| 165 | * This would correspond to the following inner class implementation: | ||
| 166 | * | ||
| 167 | * <blockquote> | ||
| 168 | *<pre> | ||
| 169 | //Equivalent code using an inner class instead of EventHandler. | ||
| 170 | *new ActionListener() { | ||
| 171 | * public void actionPerformed(ActionEvent e) { | ||
| 172 | * target.doActionEvent(e); | ||
| 173 | * } | ||
| 174 | *} | ||
| 175 | *</pre> | ||
| 176 | * </blockquote> | ||
| 177 | * | ||
| 178 | * Probably the most common use of <code>EventHandler</code> | ||
| 179 | * is to extract a property value from the | ||
| 180 | * <em>source</em> of the event object and set this value as | ||
| 181 | * the value of a property of the target object. | ||
| 182 | * In the following example we create an <code>ActionListener</code> that | ||
| 183 | * sets the "label" property of the target | ||
| 184 | * object to the value of the "text" property of the | ||
| 185 | * source (the value of the "source" property) of the event. | ||
| 186 | * | ||
| 187 | * <blockquote> | ||
| 188 | *<pre> | ||
| 189 | *EventHandler.create(ActionListener.class, myButton, "label", "source.text") | ||
| 190 | *</pre> | ||
| 191 | * </blockquote> | ||
| 192 | * | ||
| 193 | * This would correspond to the following inner class implementation: | ||
| 194 | * | ||
| 195 | * <blockquote> | ||
| 196 | *<pre> | ||
| 197 | //Equivalent code using an inner class instead of EventHandler. | ||
| 198 | *new ActionListener { | ||
| 199 | * public void actionPerformed(ActionEvent e) { | ||
| 200 | * myButton.setLabel(((JTextField)e.getSource()).getText()); | ||
| 201 | * } | ||
| 202 | *} | ||
| 203 | *</pre> | ||
| 204 | * </blockquote> | ||
| 205 | * | ||
| 206 | * The event property may be "qualified" with an arbitrary number | ||
| 207 | * of property prefixes delimited with the "." character. The "qualifying" | ||
| 208 | * names that appear before the "." characters are taken as the names of | ||
| 209 | * properties that should be applied, left-most first, to | ||
| 210 | * the event object. | ||
| 211 | * <p> | ||
| 212 | * For example, the following action listener | ||
| 213 | * | ||
| 214 | * <blockquote> | ||
| 215 | *<pre> | ||
| 216 | *EventHandler.create(ActionListener.class, target, "a", "b.c.d") | ||
| 217 | *</pre> | ||
| 218 | * </blockquote> | ||
| 219 | * | ||
| 220 | * might be written as the following inner class | ||
| 221 | * (assuming all the properties had canonical getter methods and | ||
| 222 | * returned the appropriate types): | ||
| 223 | * | ||
| 224 | * <blockquote> | ||
| 225 | *<pre> | ||
| 226 | //Equivalent code using an inner class instead of EventHandler. | ||
| 227 | *new ActionListener { | ||
| 228 | * public void actionPerformed(ActionEvent e) { | ||
| 229 | * target.setA(e.getB().getC().isD()); | ||
| 230 | * } | ||
| 231 | *} | ||
| 232 | *</pre> | ||
| 233 | * </blockquote> | ||
| 234 | * The target property may also be "qualified" with an arbitrary number | ||
| 235 | * of property prefixs delimited with the "." character. For example, the | ||
| 236 | * following action listener: | ||
| 237 | * <pre> | ||
| 238 | * EventHandler.create(ActionListener.class, target, "a.b", "c.d") | ||
| 239 | * </pre> | ||
| 240 | * might be written as the following inner class | ||
| 241 | * (assuming all the properties had canonical getter methods and | ||
| 242 | * returned the appropriate types): | ||
| 243 | * <pre> | ||
| 244 | * //Equivalent code using an inner class instead of EventHandler. | ||
| 245 | * new ActionListener { | ||
| 246 | * public void actionPerformed(ActionEvent e) { | ||
| 247 | * target.getA().setB(e.getC().isD()); | ||
| 248 | * } | ||
| 249 | *} | ||
| 250 | *</pre> | ||
| 251 | * <p> | ||
| 252 | * As <code>EventHandler</code> ultimately relies on reflection to invoke | ||
| 253 | * a method we recommend against targeting an overloaded method. For example, | ||
| 254 | * if the target is an instance of the class <code>MyTarget</code> which is | ||
| 255 | * defined as: | ||
| 256 | * <pre> | ||
| 257 | * public class MyTarget { | ||
| 258 | * public void doIt(String); | ||
| 259 | * public void doIt(Object); | ||
| 260 | * } | ||
| 261 | * </pre> | ||
| 262 | * Then the method <code>doIt</code> is overloaded. EventHandler will invoke | ||
| 263 | * the method that is appropriate based on the source. If the source is | ||
| 264 | * null, then either method is appropriate and the one that is invoked is | ||
| 265 | * undefined. For that reason we recommend against targeting overloaded | ||
| 266 | * methods. | ||
| 267 | * | ||
| 268 | * @see java.lang.reflect.Proxy | ||
| 269 | * @see java.util.EventObject | ||
| 270 | * | ||
| 271 | * @since 1.4 | ||
| 272 | * | ||
| 273 | * @author Mark Davidson | ||
| 274 | * @author Philip Milne | ||
| 275 | * @author Hans Muller | ||
| 276 | * | ||
| 277 | */ | ||
| 278 | public class EventHandler implements InvocationHandler { | ||
| 279 | private Object target; | ||
| 280 | private String action; | ||
| 281 | private final String eventPropertyName; | ||
| 282 | private final String listenerMethodName; | ||
| 283 | private final AccessControlContext acc = AccessController.getContext(); | ||
| 284 | |||
| 285 | /** | ||
| 286 | * Creates a new <code>EventHandler</code> object; | ||
| 287 | * you generally use one of the <code>create</code> methods | ||
| 288 | * instead of invoking this constructor directly. Refer to | ||
| 289 | * {@link java.beans.EventHandler#create(Class, Object, String, String) | ||
| 290 | * the general version of create} for a complete description of | ||
| 291 | * the <code>eventPropertyName</code> and <code>listenerMethodName</code> | ||
| 292 | * parameter. | ||
| 293 | * | ||
| 294 | * @param target the object that will perform the action | ||
| 295 | * @param action the name of a (possibly qualified) property or method on | ||
| 296 | * the target | ||
| 297 | * @param eventPropertyName the (possibly qualified) name of a readable property of the incoming event | ||
| 298 | * @param listenerMethodName the name of the method in the listener interface that should trigger the action | ||
| 299 | * | ||
| 300 | * @throws NullPointerException if <code>target</code> is null | ||
| 301 | * @throws NullPointerException if <code>action</code> is null | ||
| 302 | * | ||
| 303 | * @see EventHandler | ||
| 304 | * @see #create(Class, Object, String, String, String) | ||
| 305 | * @see #getTarget | ||
| 306 | * @see #getAction | ||
| 307 | * @see #getEventPropertyName | ||
| 308 | * @see #getListenerMethodName | ||
| 309 | */ | ||
| 310 | @ConstructorProperties({"target", "action", "eventPropertyName", "listenerMethodName"}) | ||
| 311 | public EventHandler(Object target, String action, String eventPropertyName, String listenerMethodName) { | ||
| 312 | this.target = target; | ||
| 313 | this.action = action; | ||
| 314 | if (target == null) { | ||
| 315 | throw new NullPointerException("target must be non-null"); | ||
| 316 | } | ||
| 317 | if (action == null) { | ||
| 318 | throw new NullPointerException("action must be non-null"); | ||
| 319 | } | ||
| 320 | this.eventPropertyName = eventPropertyName; | ||
| 321 | this.listenerMethodName = listenerMethodName; | ||
| 322 | } | ||
| 323 | |||
| 324 | /** | ||
| 325 | * Returns the object to which this event handler will send a message. | ||
| 326 | * | ||
| 327 | * @return the target of this event handler | ||
| 328 | * @see #EventHandler(Object, String, String, String) | ||
| 329 | */ | ||
| 330 | public Object getTarget() { | ||
| 331 | return target; | ||
| 332 | } | ||
| 333 | |||
| 334 | /** | ||
| 335 | * Returns the name of the target's writable property | ||
| 336 | * that this event handler will set, | ||
| 337 | * or the name of the method that this event handler | ||
| 338 | * will invoke on the target. | ||
| 339 | * | ||
| 340 | * @return the action of this event handler | ||
| 341 | * @see #EventHandler(Object, String, String, String) | ||
| 342 | */ | ||
| 343 | public String getAction() { | ||
| 344 | return action; | ||
| 345 | } | ||
| 346 | |||
| 347 | /** | ||
| 348 | * Returns the property of the event that should be | ||
| 349 | * used in the action applied to the target. | ||
| 350 | * | ||
| 351 | * @return the property of the event | ||
| 352 | * | ||
| 353 | * @see #EventHandler(Object, String, String, String) | ||
| 354 | */ | ||
| 355 | public String getEventPropertyName() { | ||
| 356 | return eventPropertyName; | ||
| 357 | } | ||
| 358 | |||
| 359 | /** | ||
| 360 | * Returns the name of the method that will trigger the action. | ||
| 361 | * A return value of <code>null</code> signifies that all methods in the | ||
| 362 | * listener interface trigger the action. | ||
| 363 | * | ||
| 364 | * @return the name of the method that will trigger the action | ||
| 365 | * | ||
| 366 | * @see #EventHandler(Object, String, String, String) | ||
| 367 | */ | ||
| 368 | public String getListenerMethodName() { | ||
| 369 | return listenerMethodName; | ||
| 370 | } | ||
| 371 | |||
| 372 | private Object applyGetters(Object target, String getters) { | ||
| 373 | if (getters == null || getters.equals("")) { | ||
| 374 | return target; | ||
| 375 | } | ||
| 376 | int firstDot = getters.indexOf('.'); | ||
| 377 | if (firstDot == -1) { | ||
| 378 | firstDot = getters.length(); | ||
| 379 | } | ||
| 380 | String first = getters.substring(0, firstDot); | ||
| 381 | String rest = getters.substring(Math.min(firstDot + 1, getters.length())); | ||
| 382 | |||
| 383 | try { | ||
| 384 | Method getter = null; | ||
| 385 | if (target != null) { | ||
| 386 | getter = Statement.getMethod(target.getClass(), | ||
| 387 | "get" + NameGenerator.capitalize(first), | ||
| 388 | new Class[]{}); | ||
| 389 | if (getter == null) { | ||
| 390 | getter = Statement.getMethod(target.getClass(), | ||
| 391 | "is" + NameGenerator.capitalize(first), | ||
| 392 | new Class[]{}); | ||
| 393 | } | ||
| 394 | if (getter == null) { | ||
| 395 | getter = Statement.getMethod(target.getClass(), first, new Class[]{}); | ||
| 396 | } | ||
| 397 | } | ||
| 398 | if (getter == null) { | ||
| 399 | throw new RuntimeException("No method called: " + first + | ||
| 400 | " defined on " + target); | ||
| 401 | } | ||
| 402 | Object newTarget = MethodUtil.invoke(getter, target, new Object[]{}); | ||
| 403 | return applyGetters(newTarget, rest); | ||
| 404 | } | ||
| 405 | catch (Exception e) { | ||
| 406 | throw new RuntimeException("Failed to call method: " + first + | ||
| 407 | " on " + target, e); | ||
| 408 | } | ||
| 409 | } | ||
| 410 | |||
| 411 | /** | ||
| 412 | * Extract the appropriate property value from the event and | ||
| 413 | * pass it to the action associated with | ||
| 414 | * this <code>EventHandler</code>. | ||
| 415 | * | ||
| 416 | * @param proxy the proxy object | ||
| 417 | * @param method the method in the listener interface | ||
| 418 | * @return the result of applying the action to the target | ||
| 419 | * | ||
| 420 | * @see EventHandler | ||
| 421 | */ | ||
| 422 | public Object invoke(final Object proxy, final Method method, final Object[] arguments) { | ||
| 423 | AccessControlContext acc = this.acc; | ||
| 424 | if ((acc == null) && (System.getSecurityManager() != null)) { | ||
| 425 | throw new SecurityException("AccessControlContext is not set"); | ||
| 426 | } | ||
| 427 | return AccessController.doPrivileged(new PrivilegedAction<Object>() { | ||
| 428 | public Object run() { | ||
| 429 | return invokeInternal(proxy, method, arguments); | ||
| 430 | } | ||
| 431 | }, acc); | ||
| 432 | } | ||
| 433 | |||
| 434 | private Object invokeInternal(Object proxy, Method method, Object[] arguments) { | ||
| 435 | String methodName = method.getName(); | ||
| 436 | if (method.getDeclaringClass() == Object.class) { | ||
| 437 | // Handle the Object public methods. | ||
| 438 | if (methodName.equals("hashCode")) { | ||
| 439 | return new Integer(System.identityHashCode(proxy)); | ||
| 440 | } else if (methodName.equals("equals")) { | ||
| 441 | return (proxy == arguments[0] ? Boolean.TRUE : Boolean.FALSE); | ||
| 442 | } else if (methodName.equals("toString")) { | ||
| 443 | return proxy.getClass().getName() + '@' + Integer.toHexString(proxy.hashCode()); | ||
| 444 | } | ||
| 445 | } | ||
| 446 | |||
| 447 | if (listenerMethodName == null || listenerMethodName.equals(methodName)) { | ||
| 448 | Class[] argTypes = null; | ||
| 449 | Object[] newArgs = null; | ||
| 450 | |||
| 451 | if (eventPropertyName == null) { // Nullary method. | ||
| 452 | newArgs = new Object[]{}; | ||
| 453 | argTypes = new Class[]{}; | ||
| 454 | } | ||
| 455 | else { | ||
| 456 | Object input = applyGetters(arguments[0], getEventPropertyName()); | ||
| 457 | newArgs = new Object[]{input}; | ||
| 458 | argTypes = new Class[]{input == null ? null : | ||
| 459 | input.getClass()}; | ||
| 460 | } | ||
| 461 | try { | ||
| 462 | int lastDot = action.lastIndexOf('.'); | ||
| 463 | if (lastDot != -1) { | ||
| 464 | target = applyGetters(target, action.substring(0, lastDot)); | ||
| 465 | action = action.substring(lastDot + 1); | ||
| 466 | } | ||
| 467 | Method targetMethod = Statement.getMethod( | ||
| 468 | target.getClass(), action, argTypes); | ||
| 469 | if (targetMethod == null) { | ||
| 470 | targetMethod = Statement.getMethod(target.getClass(), | ||
| 471 | "set" + NameGenerator.capitalize(action), argTypes); | ||
| 472 | } | ||
| 473 | if (targetMethod == null) { | ||
| 474 | String argTypeString = (argTypes.length == 0) | ||
| 475 | ? " with no arguments" | ||
| 476 | : " with argument " + argTypes[0]; | ||
| 477 | throw new RuntimeException( | ||
| 478 | "No method called " + action + " on " + | ||
| 479 | target.getClass() + argTypeString); | ||
| 480 | } | ||
| 481 | return MethodUtil.invoke(targetMethod, target, newArgs); | ||
| 482 | } | ||
| 483 | catch (IllegalAccessException ex) { | ||
| 484 | throw new RuntimeException(ex); | ||
| 485 | } | ||
| 486 | catch (InvocationTargetException ex) { | ||
| 487 | Throwable th = ex.getTargetException(); | ||
| 488 | throw (th instanceof RuntimeException) | ||
| 489 | ? (RuntimeException) th | ||
| 490 | : new RuntimeException(th); | ||
| 491 | } | ||
| 492 | } | ||
| 493 | return null; | ||
| 494 | } | ||
| 495 | |||
| 496 | /** | ||
| 497 | * Creates an implementation of <code>listenerInterface</code> in which | ||
| 498 | * <em>all</em> of the methods in the listener interface apply | ||
| 499 | * the handler's <code>action</code> to the <code>target</code>. This | ||
| 500 | * method is implemented by calling the other, more general, | ||
| 501 | * implementation of the <code>create</code> method with both | ||
| 502 | * the <code>eventPropertyName</code> and the <code>listenerMethodName</code> | ||
| 503 | * taking the value <code>null</code>. Refer to | ||
| 504 | * {@link java.beans.EventHandler#create(Class, Object, String, String) | ||
| 505 | * the general version of create} for a complete description of | ||
| 506 | * the <code>action</code> parameter. | ||
| 507 | * <p> | ||
| 508 | * To create an <code>ActionListener</code> that shows a | ||
| 509 | * <code>JDialog</code> with <code>dialog.show()</code>, | ||
| 510 | * one can write: | ||
| 511 | * | ||
| 512 | *<blockquote> | ||
| 513 | *<pre> | ||
| 514 | *EventHandler.create(ActionListener.class, dialog, "show") | ||
| 515 | *</pre> | ||
| 516 | *</blockquote> | ||
| 517 | * | ||
| 518 | * @param listenerInterface the listener interface to create a proxy for | ||
| 519 | * @param target the object that will perform the action | ||
| 520 | * @param action the name of a (possibly qualified) property or method on | ||
| 521 | * the target | ||
| 522 | * @return an object that implements <code>listenerInterface</code> | ||
| 523 | * | ||
| 524 | * @throws NullPointerException if <code>listenerInterface</code> is null | ||
| 525 | * @throws NullPointerException if <code>target</code> is null | ||
| 526 | * @throws NullPointerException if <code>action</code> is null | ||
| 527 | * | ||
| 528 | * @see #create(Class, Object, String, String) | ||
| 529 | */ | ||
| 530 | public static <T> T create(Class<T> listenerInterface, | ||
| 531 | Object target, String action) | ||
| 532 | { | ||
| 533 | return create(listenerInterface, target, action, null, null); | ||
| 534 | } | ||
| 535 | |||
| 536 | /** | ||
| 537 | /** | ||
| 538 | * Creates an implementation of <code>listenerInterface</code> in which | ||
| 539 | * <em>all</em> of the methods pass the value of the event | ||
| 540 | * expression, <code>eventPropertyName</code>, to the final method in the | ||
| 541 | * statement, <code>action</code>, which is applied to the <code>target</code>. | ||
| 542 | * This method is implemented by calling the | ||
| 543 | * more general, implementation of the <code>create</code> method with | ||
| 544 | * the <code>listenerMethodName</code> taking the value <code>null</code>. | ||
| 545 | * Refer to | ||
| 546 | * {@link java.beans.EventHandler#create(Class, Object, String, String) | ||
| 547 | * the general version of create} for a complete description of | ||
| 548 | * the <code>action</code> and <code>eventPropertyName</code> parameters. | ||
| 549 | * <p> | ||
| 550 | * To create an <code>ActionListener</code> that sets the | ||
| 551 | * the text of a <code>JLabel</code> to the text value of | ||
| 552 | * the <code>JTextField</code> source of the incoming event, | ||
| 553 | * you can use the following code: | ||
| 554 | * | ||
| 555 | *<blockquote> | ||
| 556 | *<pre> | ||
| 557 | *EventHandler.create(ActionListener.class, label, "text", "source.text"); | ||
| 558 | *</pre> | ||
| 559 | *</blockquote> | ||
| 560 | * | ||
| 561 | * This is equivalent to the following code: | ||
| 562 | *<blockquote> | ||
| 563 | *<pre> | ||
| 564 | //Equivalent code using an inner class instead of EventHandler. | ||
| 565 | *new ActionListener() { | ||
| 566 | * public void actionPerformed(ActionEvent event) { | ||
| 567 | * label.setText(((JTextField)(event.getSource())).getText()); | ||
| 568 | * } | ||
| 569 | *}; | ||
| 570 | *</pre> | ||
| 571 | *</blockquote> | ||
| 572 | * | ||
| 573 | * @param listenerInterface the listener interface to create a proxy for | ||
| 574 | * @param target the object that will perform the action | ||
| 575 | * @param action the name of a (possibly qualified) property or method on | ||
| 576 | * the target | ||
| 577 | * @param eventPropertyName the (possibly qualified) name of a readable property of the incoming event | ||
| 578 | * | ||
| 579 | * @return an object that implements <code>listenerInterface</code> | ||
| 580 | * | ||
| 581 | * @throws NullPointerException if <code>listenerInterface</code> is null | ||
| 582 | * @throws NullPointerException if <code>target</code> is null | ||
| 583 | * @throws NullPointerException if <code>action</code> is null | ||
| 584 | * | ||
| 585 | * @see #create(Class, Object, String, String, String) | ||
| 586 | */ | ||
| 587 | public static <T> T create(Class<T> listenerInterface, | ||
| 588 | Object target, String action, | ||
| 589 | String eventPropertyName) | ||
| 590 | { | ||
| 591 | return create(listenerInterface, target, action, eventPropertyName, null); | ||
| 592 | } | ||
| 593 | |||
| 594 | /** | ||
| 595 | * Creates an implementation of <code>listenerInterface</code> in which | ||
| 596 | * the method named <code>listenerMethodName</code> | ||
| 597 | * passes the value of the event expression, <code>eventPropertyName</code>, | ||
| 598 | * to the final method in the statement, <code>action</code>, which | ||
| 599 | * is applied to the <code>target</code>. All of the other listener | ||
| 600 | * methods do nothing. | ||
| 601 | * <p> | ||
| 602 | * The <code>eventPropertyName</code> string is used to extract a value | ||
| 603 | * from the incoming event object that is passed to the target | ||
| 604 | * method. The common case is the target method takes no arguments, in | ||
| 605 | * which case a value of null should be used for the | ||
| 606 | * <code>eventPropertyName</code>. Alternatively if you want | ||
| 607 | * the incoming event object passed directly to the target method use | ||
| 608 | * the empty string. | ||
| 609 | * The format of the <code>eventPropertyName</code> string is a sequence of | ||
| 610 | * methods or properties where each method or | ||
| 611 | * property is applied to the value returned by the preceeding method | ||
| 612 | * starting from the incoming event object. | ||
| 613 | * The syntax is: <code>propertyName{.propertyName}*</code> | ||
| 614 | * where <code>propertyName</code> matches a method or | ||
| 615 | * property. For example, to extract the <code>point</code> | ||
| 616 | * property from a <code>MouseEvent</code>, you could use either | ||
| 617 | * <code>"point"</code> or <code>"getPoint"</code> as the | ||
| 618 | * <code>eventPropertyName</code>. To extract the "text" property from | ||
| 619 | * a <code>MouseEvent</code> with a <code>JLabel</code> source use any | ||
| 620 | * of the following as <code>eventPropertyName</code>: | ||
| 621 | * <code>"source.text"</code>, | ||
| 622 | * <code>"getSource.text"</code> <code>"getSource.getText"</code> or | ||
| 623 | * <code>"source.getText"</code>. If a method can not be found, or an | ||
| 624 | * exception is generated as part of invoking a method a | ||
| 625 | * <code>RuntimeException</code> will be thrown at dispatch time. For | ||
| 626 | * example, if the incoming event object is null, and | ||
| 627 | * <code>eventPropertyName</code> is non-null and not empty, a | ||
| 628 | * <code>RuntimeException</code> will be thrown. | ||
| 629 | * <p> | ||
| 630 | * The <code>action</code> argument is of the same format as the | ||
| 631 | * <code>eventPropertyName</code> argument where the last property name | ||
| 632 | * identifies either a method name or writable property. | ||
| 633 | * <p> | ||
| 634 | * If the <code>listenerMethodName</code> is <code>null</code> | ||
| 635 | * <em>all</em> methods in the interface trigger the <code>action</code> to be | ||
| 636 | * executed on the <code>target</code>. | ||
| 637 | * <p> | ||
| 638 | * For example, to create a <code>MouseListener</code> that sets the target | ||
| 639 | * object's <code>origin</code> property to the incoming <code>MouseEvent</code>'s | ||
| 640 | * location (that's the value of <code>mouseEvent.getPoint()</code>) each | ||
| 641 | * time a mouse button is pressed, one would write: | ||
| 642 | *<blockquote> | ||
| 643 | *<pre> | ||
| 644 | *EventHandler.create(MouseListener.class, target, "origin", "point", "mousePressed"); | ||
| 645 | *</pre> | ||
| 646 | *</blockquote> | ||
| 647 | * | ||
| 648 | * This is comparable to writing a <code>MouseListener</code> in which all | ||
| 649 | * of the methods except <code>mousePressed</code> are no-ops: | ||
| 650 | * | ||
| 651 | *<blockquote> | ||
| 652 | *<pre> | ||
| 653 | //Equivalent code using an inner class instead of EventHandler. | ||
| 654 | *new MouseAdapter() { | ||
| 655 | * public void mousePressed(MouseEvent e) { | ||
| 656 | * target.setOrigin(e.getPoint()); | ||
| 657 | * } | ||
| 658 | *}; | ||
| 659 | * </pre> | ||
| 660 | *</blockquote> | ||
| 661 | * | ||
| 662 | * @param listenerInterface the listener interface to create a proxy for | ||
| 663 | * @param target the object that will perform the action | ||
| 664 | * @param action the name of a (possibly qualified) property or method on | ||
| 665 | * the target | ||
| 666 | * @param eventPropertyName the (possibly qualified) name of a readable property of the incoming event | ||
| 667 | * @param listenerMethodName the name of the method in the listener interface that should trigger the action | ||
| 668 | * | ||
| 669 | * @return an object that implements <code>listenerInterface</code> | ||
| 670 | * | ||
| 671 | * @throws NullPointerException if <code>listenerInterface</code> is null | ||
| 672 | * @throws NullPointerException if <code>target</code> is null | ||
| 673 | * @throws NullPointerException if <code>action</code> is null | ||
| 674 | * | ||
| 675 | * @see EventHandler | ||
| 676 | */ | ||
| 677 | public static <T> T create(Class<T> listenerInterface, | ||
| 678 | Object target, String action, | ||
| 679 | String eventPropertyName, | ||
| 680 | String listenerMethodName) | ||
| 681 | { | ||
| 682 | // Create this first to verify target/action are non-null | ||
| 683 | EventHandler eventHandler = new EventHandler(target, action, | ||
| 684 | eventPropertyName, | ||
| 685 | listenerMethodName); | ||
| 686 | if (listenerInterface == null) { | ||
| 687 | throw new NullPointerException( | ||
| 688 | "listenerInterface must be non-null"); | ||
| 689 | } | ||
| 690 | return (T)Proxy.newProxyInstance(target.getClass().getClassLoader(), | ||
| 691 | new Class[] {listenerInterface}, | ||
| 692 | eventHandler); | ||
| 693 | } | ||
| 694 | } | ||