J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 2000-2006 Sun Microsystems, Inc. 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. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 23 | * have any questions. |
| 24 | */ |
| 25 | package java.beans; |
| 26 | |
| 27 | import java.util.*; |
| 28 | import java.lang.reflect.*; |
| 29 | import sun.reflect.misc.*; |
| 30 | |
| 31 | |
| 32 | /** |
| 33 | * The <code>DefaultPersistenceDelegate</code> is a concrete implementation of |
| 34 | * the abstract <code>PersistenceDelegate</code> class and |
| 35 | * is the delegate used by default for classes about |
| 36 | * which no information is available. The <code>DefaultPersistenceDelegate</code> |
| 37 | * provides, version resilient, public API-based persistence for |
| 38 | * classes that follow the JavaBeans conventions without any class specific |
| 39 | * configuration. |
| 40 | * <p> |
| 41 | * The key assumptions are that the class has a nullary constructor |
| 42 | * and that its state is accurately represented by matching pairs |
| 43 | * of "setter" and "getter" methods in the order they are returned |
| 44 | * by the Introspector. |
| 45 | * In addition to providing code-free persistence for JavaBeans, |
| 46 | * the <code>DefaultPersistenceDelegate</code> provides a convenient means |
| 47 | * to effect persistent storage for classes that have a constructor |
| 48 | * that, while not nullary, simply requires some property values |
| 49 | * as arguments. |
| 50 | * |
| 51 | * @see #DefaultPersistenceDelegate(String[]) |
| 52 | * @see java.beans.Introspector |
| 53 | * |
| 54 | * @since 1.4 |
| 55 | * |
| 56 | * @author Philip Milne |
| 57 | */ |
| 58 | |
| 59 | public class DefaultPersistenceDelegate extends PersistenceDelegate { |
| 60 | private String[] constructor; |
| 61 | private Boolean definesEquals; |
| 62 | |
| 63 | /** |
| 64 | * Creates a persistence delegate for a class with a nullary constructor. |
| 65 | * |
| 66 | * @see #DefaultPersistenceDelegate(java.lang.String[]) |
| 67 | */ |
| 68 | public DefaultPersistenceDelegate() { |
| 69 | this(new String[0]); |
| 70 | } |
| 71 | |
| 72 | /** |
| 73 | * Creates a default persistence delegate for a class with a |
| 74 | * constructor whose arguments are the values of the property |
| 75 | * names as specified by <code>constructorPropertyNames</code>. |
| 76 | * The constructor arguments are created by |
| 77 | * evaluating the property names in the order they are supplied. |
| 78 | * To use this class to specify a single preferred constructor for use |
| 79 | * in the serialization of a particular type, we state the |
| 80 | * names of the properties that make up the constructor's |
| 81 | * arguments. For example, the <code>Font</code> class which |
| 82 | * does not define a nullary constructor can be handled |
| 83 | * with the following persistence delegate: |
| 84 | * |
| 85 | * <pre> |
| 86 | * new DefaultPersistenceDelegate(new String[]{"name", "style", "size"}); |
| 87 | * </pre> |
| 88 | * |
| 89 | * @param constructorPropertyNames The property names for the arguments of this constructor. |
| 90 | * |
| 91 | * @see #instantiate |
| 92 | */ |
| 93 | public DefaultPersistenceDelegate(String[] constructorPropertyNames) { |
| 94 | this.constructor = constructorPropertyNames; |
| 95 | } |
| 96 | |
| 97 | private static boolean definesEquals(Class type) { |
| 98 | try { |
| 99 | return type == type.getMethod("equals", Object.class).getDeclaringClass(); |
| 100 | } |
| 101 | catch(NoSuchMethodException e) { |
| 102 | return false; |
| 103 | } |
| 104 | } |
| 105 | |
| 106 | private boolean definesEquals(Object instance) { |
| 107 | if (definesEquals != null) { |
| 108 | return (definesEquals == Boolean.TRUE); |
| 109 | } |
| 110 | else { |
| 111 | boolean result = definesEquals(instance.getClass()); |
| 112 | definesEquals = result ? Boolean.TRUE : Boolean.FALSE; |
| 113 | return result; |
| 114 | } |
| 115 | } |
| 116 | |
| 117 | /** |
| 118 | * If the number of arguments in the specified constructor is non-zero and |
| 119 | * the class of <code>oldInstance</code> explicitly declares an "equals" method |
| 120 | * this method returns the value of <code>oldInstance.equals(newInstance)</code>. |
| 121 | * Otherwise, this method uses the superclass's definition which returns true if the |
| 122 | * classes of the two instances are equal. |
| 123 | * |
| 124 | * @param oldInstance The instance to be copied. |
| 125 | * @param newInstance The instance that is to be modified. |
| 126 | * @return True if an equivalent copy of <code>newInstance</code> may be |
| 127 | * created by applying a series of mutations to <code>oldInstance</code>. |
| 128 | * |
| 129 | * @see #DefaultPersistenceDelegate(String[]) |
| 130 | */ |
| 131 | protected boolean mutatesTo(Object oldInstance, Object newInstance) { |
| 132 | // Assume the instance is either mutable or a singleton |
| 133 | // if it has a nullary constructor. |
| 134 | return (constructor.length == 0) || !definesEquals(oldInstance) ? |
| 135 | super.mutatesTo(oldInstance, newInstance) : |
| 136 | oldInstance.equals(newInstance); |
| 137 | } |
| 138 | |
| 139 | /** |
| 140 | * This default implementation of the <code>instantiate</code> method returns |
| 141 | * an expression containing the predefined method name "new" which denotes a |
| 142 | * call to a constructor with the arguments as specified in |
| 143 | * the <code>DefaultPersistenceDelegate</code>'s constructor. |
| 144 | * |
| 145 | * @param oldInstance The instance to be instantiated. |
| 146 | * @param out The code output stream. |
| 147 | * @return An expression whose value is <code>oldInstance</code>. |
| 148 | * |
| 149 | * @see #DefaultPersistenceDelegate(String[]) |
| 150 | */ |
| 151 | protected Expression instantiate(Object oldInstance, Encoder out) { |
| 152 | int nArgs = constructor.length; |
| 153 | Class type = oldInstance.getClass(); |
| 154 | Object[] constructorArgs = new Object[nArgs]; |
| 155 | for(int i = 0; i < nArgs; i++) { |
| 156 | try { |
| 157 | Method method = findMethod(type, this.constructor[i]); |
| 158 | constructorArgs[i] = MethodUtil.invoke(method, oldInstance, new Object[0]); |
| 159 | } |
| 160 | catch (Exception e) { |
| 161 | out.getExceptionListener().exceptionThrown(e); |
| 162 | } |
| 163 | } |
| 164 | return new Expression(oldInstance, oldInstance.getClass(), "new", constructorArgs); |
| 165 | } |
| 166 | |
| 167 | private Method findMethod(Class type, String property) throws IntrospectionException { |
| 168 | if (property == null) { |
| 169 | throw new IllegalArgumentException("Property name is null"); |
| 170 | } |
| 171 | BeanInfo info = Introspector.getBeanInfo(type); |
| 172 | for (PropertyDescriptor pd : info.getPropertyDescriptors()) { |
| 173 | if (property.equals(pd.getName())) { |
| 174 | Method method = pd.getReadMethod(); |
| 175 | if (method != null) { |
| 176 | return method; |
| 177 | } |
| 178 | throw new IllegalStateException("Could not find getter for the property " + property); |
| 179 | } |
| 180 | } |
| 181 | throw new IllegalStateException("Could not find property by the name " + property); |
| 182 | } |
| 183 | |
| 184 | // This is a workaround for a bug in the introspector. |
| 185 | // PropertyDescriptors are not shared amongst subclasses. |
| 186 | private boolean isTransient(Class type, PropertyDescriptor pd) { |
| 187 | if (type == null) { |
| 188 | return false; |
| 189 | } |
| 190 | // This code was mistakenly deleted - it may be fine and |
| 191 | // is more efficient than the code below. This should |
| 192 | // all disappear anyway when property descriptors are shared |
| 193 | // by the introspector. |
| 194 | /* |
| 195 | Method getter = pd.getReadMethod(); |
| 196 | Class declaringClass = getter.getDeclaringClass(); |
| 197 | if (declaringClass == type) { |
| 198 | return Boolean.TRUE.equals(pd.getValue("transient")); |
| 199 | } |
| 200 | */ |
| 201 | String pName = pd.getName(); |
| 202 | BeanInfo info = MetaData.getBeanInfo(type); |
| 203 | PropertyDescriptor[] propertyDescriptors = info.getPropertyDescriptors(); |
| 204 | for (int i = 0; i < propertyDescriptors.length; ++i ) { |
| 205 | PropertyDescriptor pd2 = propertyDescriptors[i]; |
| 206 | if (pName.equals(pd2.getName())) { |
| 207 | Object value = pd2.getValue("transient"); |
| 208 | if (value != null) { |
| 209 | return Boolean.TRUE.equals(value); |
| 210 | } |
| 211 | } |
| 212 | } |
| 213 | return isTransient(type.getSuperclass(), pd); |
| 214 | } |
| 215 | |
| 216 | private static boolean equals(Object o1, Object o2) { |
| 217 | return (o1 == null) ? (o2 == null) : o1.equals(o2); |
| 218 | } |
| 219 | |
| 220 | private void doProperty(Class type, PropertyDescriptor pd, Object oldInstance, Object newInstance, Encoder out) throws Exception { |
| 221 | Method getter = pd.getReadMethod(); |
| 222 | Method setter = pd.getWriteMethod(); |
| 223 | |
| 224 | if (getter != null && setter != null && !isTransient(type, pd)) { |
| 225 | Expression oldGetExp = new Expression(oldInstance, getter.getName(), new Object[]{}); |
| 226 | Expression newGetExp = new Expression(newInstance, getter.getName(), new Object[]{}); |
| 227 | Object oldValue = oldGetExp.getValue(); |
| 228 | Object newValue = newGetExp.getValue(); |
| 229 | out.writeExpression(oldGetExp); |
| 230 | if (!equals(newValue, out.get(oldValue))) { |
| 231 | // Search for a static constant with this value; |
| 232 | Object e = (Object[])pd.getValue("enumerationValues"); |
| 233 | if (e instanceof Object[] && Array.getLength(e) % 3 == 0) { |
| 234 | Object[] a = (Object[])e; |
| 235 | for(int i = 0; i < a.length; i = i + 3) { |
| 236 | try { |
| 237 | Field f = type.getField((String)a[i]); |
| 238 | if (f.get(null).equals(oldValue)) { |
| 239 | out.remove(oldValue); |
| 240 | out.writeExpression(new Expression(oldValue, f, "get", new Object[]{null})); |
| 241 | } |
| 242 | } |
| 243 | catch (Exception ex) {} |
| 244 | } |
| 245 | } |
| 246 | invokeStatement(oldInstance, setter.getName(), new Object[]{oldValue}, out); |
| 247 | } |
| 248 | } |
| 249 | } |
| 250 | |
| 251 | static void invokeStatement(Object instance, String methodName, Object[] args, Encoder out) { |
| 252 | out.writeStatement(new Statement(instance, methodName, args)); |
| 253 | } |
| 254 | |
| 255 | // Write out the properties of this instance. |
| 256 | private void initBean(Class type, Object oldInstance, Object newInstance, Encoder out) { |
| 257 | // System.out.println("initBean: " + oldInstance); |
| 258 | BeanInfo info = MetaData.getBeanInfo(type); |
| 259 | |
| 260 | // Properties |
| 261 | PropertyDescriptor[] propertyDescriptors = info.getPropertyDescriptors(); |
| 262 | for (int i = 0; i < propertyDescriptors.length; ++i ) { |
| 263 | try { |
| 264 | doProperty(type, propertyDescriptors[i], oldInstance, newInstance, out); |
| 265 | } |
| 266 | catch (Exception e) { |
| 267 | out.getExceptionListener().exceptionThrown(e); |
| 268 | } |
| 269 | } |
| 270 | |
| 271 | // Listeners |
| 272 | /* |
| 273 | Pending(milne). There is a general problem with the archival of |
| 274 | listeners which is unresolved as of 1.4. Many of the methods |
| 275 | which install one object inside another (typically "add" methods |
| 276 | or setters) automatically install a listener on the "child" object |
| 277 | so that its "parent" may respond to changes that are made to it. |
| 278 | For example the JTable:setModel() method automatically adds a |
| 279 | TableModelListener (the JTable itself in this case) to the supplied |
| 280 | table model. |
| 281 | |
| 282 | We do not need to explictly add these listeners to the model in an |
| 283 | archive as they will be added automatically by, in the above case, |
| 284 | the JTable's "setModel" method. In some cases, we must specifically |
| 285 | avoid trying to do this since the listener may be an inner class |
| 286 | that cannot be instantiated using public API. |
| 287 | |
| 288 | No general mechanism currently |
| 289 | exists for differentiating between these kind of listeners and |
| 290 | those which were added explicitly by the user. A mechanism must |
| 291 | be created to provide a general means to differentiate these |
| 292 | special cases so as to provide reliable persistence of listeners |
| 293 | for the general case. |
| 294 | */ |
| 295 | if (!java.awt.Component.class.isAssignableFrom(type)) { |
| 296 | return; // Just handle the listeners of Components for now. |
| 297 | } |
| 298 | EventSetDescriptor[] eventSetDescriptors = info.getEventSetDescriptors(); |
| 299 | for (int e = 0; e < eventSetDescriptors.length; e++) { |
| 300 | EventSetDescriptor d = eventSetDescriptors[e]; |
| 301 | Class listenerType = d.getListenerType(); |
| 302 | |
| 303 | |
| 304 | // The ComponentListener is added automatically, when |
| 305 | // Contatiner:add is called on the parent. |
| 306 | if (listenerType == java.awt.event.ComponentListener.class) { |
| 307 | continue; |
| 308 | } |
| 309 | |
| 310 | // JMenuItems have a change listener added to them in |
| 311 | // their "add" methods to enable accessibility support - |
| 312 | // see the add method in JMenuItem for details. We cannot |
| 313 | // instantiate this instance as it is a private inner class |
| 314 | // and do not need to do this anyway since it will be created |
| 315 | // and installed by the "add" method. Special case this for now, |
| 316 | // ignoring all change listeners on JMenuItems. |
| 317 | if (listenerType == javax.swing.event.ChangeListener.class && |
| 318 | type == javax.swing.JMenuItem.class) { |
| 319 | continue; |
| 320 | } |
| 321 | |
| 322 | EventListener[] oldL = new EventListener[0]; |
| 323 | EventListener[] newL = new EventListener[0]; |
| 324 | try { |
| 325 | Method m = d.getGetListenerMethod(); |
| 326 | oldL = (EventListener[])MethodUtil.invoke(m, oldInstance, new Object[]{}); |
| 327 | newL = (EventListener[])MethodUtil.invoke(m, newInstance, new Object[]{}); |
| 328 | } |
| 329 | catch (Throwable e2) { |
| 330 | try { |
| 331 | Method m = type.getMethod("getListeners", new Class[]{Class.class}); |
| 332 | oldL = (EventListener[])MethodUtil.invoke(m, oldInstance, new Object[]{listenerType}); |
| 333 | newL = (EventListener[])MethodUtil.invoke(m, newInstance, new Object[]{listenerType}); |
| 334 | } |
| 335 | catch (Exception e3) { |
| 336 | return; |
| 337 | } |
| 338 | } |
| 339 | |
| 340 | // Asssume the listeners are in the same order and that there are no gaps. |
| 341 | // Eventually, this may need to do true differencing. |
| 342 | String addListenerMethodName = d.getAddListenerMethod().getName(); |
| 343 | for (int i = newL.length; i < oldL.length; i++) { |
| 344 | // System.out.println("Adding listener: " + addListenerMethodName + oldL[i]); |
| 345 | invokeStatement(oldInstance, addListenerMethodName, new Object[]{oldL[i]}, out); |
| 346 | } |
| 347 | |
| 348 | String removeListenerMethodName = d.getRemoveListenerMethod().getName(); |
| 349 | for (int i = oldL.length; i < newL.length; i++) { |
| 350 | invokeStatement(oldInstance, removeListenerMethodName, new Object[]{newL[i]}, out); |
| 351 | } |
| 352 | } |
| 353 | } |
| 354 | |
| 355 | /** |
| 356 | * This default implementation of the <code>initialize</code> method assumes |
| 357 | * all state held in objects of this type is exposed via the |
| 358 | * matching pairs of "setter" and "getter" methods in the order |
| 359 | * they are returned by the Introspector. If a property descriptor |
| 360 | * defines a "transient" attribute with a value equal to |
| 361 | * <code>Boolean.TRUE</code> the property is ignored by this |
| 362 | * default implementation. Note that this use of the word |
| 363 | * "transient" is quite independent of the field modifier |
| 364 | * that is used by the <code>ObjectOutputStream</code>. |
| 365 | * <p> |
| 366 | * For each non-transient property, an expression is created |
| 367 | * in which the nullary "getter" method is applied |
| 368 | * to the <code>oldInstance</code>. The value of this |
| 369 | * expression is the value of the property in the instance that is |
| 370 | * being serialized. If the value of this expression |
| 371 | * in the cloned environment <code>mutatesTo</code> the |
| 372 | * target value, the new value is initialized to make it |
| 373 | * equivalent to the old value. In this case, because |
| 374 | * the property value has not changed there is no need to |
| 375 | * call the corresponding "setter" method and no statement |
| 376 | * is emitted. If not however, the expression for this value |
| 377 | * is replaced with another expression (normally a constructor) |
| 378 | * and the corresponding "setter" method is called to install |
| 379 | * the new property value in the object. This scheme removes |
| 380 | * default information from the output produced by streams |
| 381 | * using this delegate. |
| 382 | * <p> |
| 383 | * In passing these statements to the output stream, where they |
| 384 | * will be executed, side effects are made to the <code>newInstance</code>. |
| 385 | * In most cases this allows the problem of properties |
| 386 | * whose values depend on each other to actually help the |
| 387 | * serialization process by making the number of statements |
| 388 | * that need to be written to the output smaller. In general, |
| 389 | * the problem of handling interdependent properties is reduced to |
| 390 | * that of finding an order for the properties in |
| 391 | * a class such that no property value depends on the value of |
| 392 | * a subsequent property. |
| 393 | * |
| 394 | * @param oldInstance The instance to be copied. |
| 395 | * @param newInstance The instance that is to be modified. |
| 396 | * @param out The stream to which any initialization statements should be written. |
| 397 | * |
| 398 | * @see java.beans.Introspector#getBeanInfo |
| 399 | * @see java.beans.PropertyDescriptor |
| 400 | */ |
| 401 | protected void initialize(Class<?> type, |
| 402 | Object oldInstance, Object newInstance, |
| 403 | Encoder out) |
| 404 | { |
| 405 | // System.out.println("DefulatPD:initialize" + type); |
| 406 | super.initialize(type, oldInstance, newInstance, out); |
| 407 | if (oldInstance.getClass() == type) { // !type.isInterface()) { |
| 408 | initBean(type, oldInstance, newInstance, out); |
| 409 | } |
| 410 | } |
| 411 | } |