+ * Here is an example of {@code VetoableChangeSupport} usage that follows + * the rules and recommendations laid out in the JavaBeans™ specification: + *
+ * public class MyBean {
+ * private final VetoableChangeSupport vcs = new VetoableChangeSupport(this);
+ *
+ * public void addVetoableChangeListener(VetoableChangeListener listener) {
+ * this.vcs.addVetoableChangeListener(listener);
+ * }
+ *
+ * public void removeVetoableChangeListener(VetoableChangeListener listener) {
+ * this.vcs.removeVetoableChangeListener(listener);
+ * }
+ *
+ * private String value;
+ *
+ * public String getValue() {
+ * return this.value;
+ * }
+ *
+ * public void setValue(String newValue) throws PropertyVetoException {
+ * String oldValue = this.value;
+ * this.vcs.fireVetoableChange("value", oldValue, newValue);
+ * this.value = newValue;
+ * }
+ *
+ * [...]
+ * }
+ *
+ * + * A {@code VetoableChangeSupport} instance is thread-safe. + *
+ * This class is serializable. When it is serialized it will save
+ * (and restore) any listeners that are themselves serializable. Any
+ * non-serializable listeners will be skipped during serialization.
+ *
+ * @see PropertyChangeSupport
+ */
+public class VetoableChangeSupport implements Serializable {
+ private VetoableChangeListenerMap map = new VetoableChangeListenerMap();
+
+ /**
+ * Constructs a VetoableChangeSupport object.
+ *
+ * @param sourceBean The bean to be given as the source for any events.
+ */
+ public VetoableChangeSupport(Object sourceBean) {
+ if (sourceBean == null) {
+ throw new NullPointerException();
+ }
+ source = sourceBean;
+ }
+
+ /**
+ * Add a VetoableChangeListener to the listener list.
+ * The listener is registered for all properties.
+ * The same listener object may be added more than once, and will be called
+ * as many times as it is added.
+ * If listener is null, no exception is thrown and no action
+ * is taken.
+ *
+ * @param listener The VetoableChangeListener to be added
+ */
+ public void addVetoableChangeListener(VetoableChangeListener listener) {
+ if (listener == null) {
+ return;
+ }
+ if (listener instanceof VetoableChangeListenerProxy) {
+ VetoableChangeListenerProxy proxy =
+ (VetoableChangeListenerProxy)listener;
+ // Call two argument add method.
+ addVetoableChangeListener(proxy.getPropertyName(),
+ proxy.getListener());
+ } else {
+ this.map.add(null, listener);
+ }
+ }
+
+ /**
+ * Remove a VetoableChangeListener from the listener list.
+ * This removes a VetoableChangeListener that was registered
+ * for all properties.
+ * If listener was added more than once to the same event
+ * source, it will be notified one less time after being removed.
+ * If listener is null, or was never added, no exception is
+ * thrown and no action is taken.
+ *
+ * @param listener The VetoableChangeListener to be removed
+ */
+ public void removeVetoableChangeListener(VetoableChangeListener listener) {
+ if (listener == null) {
+ return;
+ }
+ if (listener instanceof VetoableChangeListenerProxy) {
+ VetoableChangeListenerProxy proxy =
+ (VetoableChangeListenerProxy)listener;
+ // Call two argument remove method.
+ removeVetoableChangeListener(proxy.getPropertyName(),
+ proxy.getListener());
+ } else {
+ this.map.remove(null, listener);
+ }
+ }
+
+ /**
+ * Returns an array of all the listeners that were added to the
+ * VetoableChangeSupport object with addVetoableChangeListener().
+ *
+ * If some listeners have been added with a named property, then
+ * the returned array will be a mixture of VetoableChangeListeners
+ * and VetoableChangeListenerProxys. If the calling
+ * method is interested in distinguishing the listeners then it must
+ * test each element to see if it's a
+ * VetoableChangeListenerProxy, perform the cast, and examine
+ * the parameter.
+ *
+ *
+ * VetoableChangeListener[] listeners = bean.getVetoableChangeListeners();
+ * for (int i = 0; i < listeners.length; i++) {
+ * if (listeners[i] instanceof VetoableChangeListenerProxy) {
+ * VetoableChangeListenerProxy proxy =
+ * (VetoableChangeListenerProxy)listeners[i];
+ * if (proxy.getPropertyName().equals("foo")) {
+ * // proxy is a VetoableChangeListener which was associated
+ * // with the property named "foo"
+ * }
+ * }
+ * }
+ *
+ *
+ * @see VetoableChangeListenerProxy
+ * @return all of the VetoableChangeListeners added or an
+ * empty array if no listeners have been added
+ * @since 1.4
+ */
+ public VetoableChangeListener[] getVetoableChangeListeners(){
+ return this.map.getListeners();
+ }
+
+ /**
+ * Add a VetoableChangeListener for a specific property. The listener
+ * will be invoked only when a call on fireVetoableChange names that
+ * specific property.
+ * The same listener object may be added more than once. For each
+ * property, the listener will be invoked the number of times it was added
+ * for that property.
+ * If propertyName or listener is null, no
+ * exception is thrown and no action is taken.
+ *
+ * @param propertyName The name of the property to listen on.
+ * @param listener The VetoableChangeListener to be added
+ */
+ public void addVetoableChangeListener(
+ String propertyName,
+ VetoableChangeListener listener) {
+ if (listener == null || propertyName == null) {
+ return;
+ }
+ listener = this.map.extract(listener);
+ if (listener != null) {
+ this.map.add(propertyName, listener);
+ }
+ }
+
+ /**
+ * Remove a VetoableChangeListener for a specific property.
+ * If listener was added more than once to the same event
+ * source for the specified property, it will be notified one less time
+ * after being removed.
+ * If propertyName is null, no exception is thrown and no
+ * action is taken.
+ * If listener is null, or was never added for the specified
+ * property, no exception is thrown and no action is taken.
+ *
+ * @param propertyName The name of the property that was listened on.
+ * @param listener The VetoableChangeListener to be removed
+ */
+ public void removeVetoableChangeListener(
+ String propertyName,
+ VetoableChangeListener listener) {
+ if (listener == null || propertyName == null) {
+ return;
+ }
+ listener = this.map.extract(listener);
+ if (listener != null) {
+ this.map.remove(propertyName, listener);
+ }
+ }
+
+ /**
+ * Returns an array of all the listeners which have been associated
+ * with the named property.
+ *
+ * @param propertyName The name of the property being listened to
+ * @return all the VetoableChangeListeners associated with
+ * the named property. If no such listeners have been added,
+ * or if propertyName is null, an empty array is
+ * returned.
+ * @since 1.4
+ */
+ public VetoableChangeListener[] getVetoableChangeListeners(String propertyName) {
+ return this.map.getListeners(propertyName);
+ }
+
+ /**
+ * Reports a constrained property update to listeners
+ * that have been registered to track updates of
+ * all properties or a property with the specified name.
+ * + * Any listener can throw a {@code PropertyVetoException} to veto the update. + * If one of the listeners vetoes the update, this method passes + * a new "undo" {@code PropertyChangeEvent} that reverts to the old value + * to all listeners that already confirmed this update + * and throws the {@code PropertyVetoException} again. + *
+ * No event is fired if old and new values are equal and non-null. + *
+ * This is merely a convenience wrapper around the more general + * {@link #fireVetoableChange(PropertyChangeEvent)} method. + * + * @param propertyName the programmatic name of the property that is about to change + * @param oldValue the old value of the property + * @param newValue the new value of the property + * @throws PropertyVetoException if one of listeners vetoes the property update + */ + public void fireVetoableChange(String propertyName, Object oldValue, Object newValue) + throws PropertyVetoException { + if (oldValue == null || newValue == null || !oldValue.equals(newValue)) { + fireVetoableChange(new PropertyChangeEvent(this.source, propertyName, oldValue, newValue)); + } + } + + /** + * Reports an integer constrained property update to listeners + * that have been registered to track updates of + * all properties or a property with the specified name. + *
+ * Any listener can throw a {@code PropertyVetoException} to veto the update. + * If one of the listeners vetoes the update, this method passes + * a new "undo" {@code PropertyChangeEvent} that reverts to the old value + * to all listeners that already confirmed this update + * and throws the {@code PropertyVetoException} again. + *
+ * No event is fired if old and new values are equal. + *
+ * This is merely a convenience wrapper around the more general + * {@link #fireVetoableChange(String, Object, Object)} method. + * + * @param propertyName the programmatic name of the property that is about to change + * @param oldValue the old value of the property + * @param newValue the new value of the property + * @throws PropertyVetoException if one of listeners vetoes the property update + */ + public void fireVetoableChange(String propertyName, int oldValue, int newValue) + throws PropertyVetoException { + if (oldValue != newValue) { + fireVetoableChange(propertyName, Integer.valueOf(oldValue), Integer.valueOf(newValue)); + } + } + + /** + * Reports a boolean constrained property update to listeners + * that have been registered to track updates of + * all properties or a property with the specified name. + *
+ * Any listener can throw a {@code PropertyVetoException} to veto the update. + * If one of the listeners vetoes the update, this method passes + * a new "undo" {@code PropertyChangeEvent} that reverts to the old value + * to all listeners that already confirmed this update + * and throws the {@code PropertyVetoException} again. + *
+ * No event is fired if old and new values are equal. + *
+ * This is merely a convenience wrapper around the more general + * {@link #fireVetoableChange(String, Object, Object)} method. + * + * @param propertyName the programmatic name of the property that is about to change + * @param oldValue the old value of the property + * @param newValue the new value of the property + * @throws PropertyVetoException if one of listeners vetoes the property update + */ + public void fireVetoableChange(String propertyName, boolean oldValue, boolean newValue) + throws PropertyVetoException { + if (oldValue != newValue) { + fireVetoableChange(propertyName, Boolean.valueOf(oldValue), Boolean.valueOf(newValue)); + } + } + + /** + * Fires a property change event to listeners + * that have been registered to track updates of + * all properties or a property with the specified name. + *
+ * Any listener can throw a {@code PropertyVetoException} to veto the update. + * If one of the listeners vetoes the update, this method passes + * a new "undo" {@code PropertyChangeEvent} that reverts to the old value + * to all listeners that already confirmed this update + * and throws the {@code PropertyVetoException} again. + *
+ * No event is fired if the given event's old and new values are equal and non-null.
+ *
+ * @param event the {@code PropertyChangeEvent} to be fired
+ * @throws PropertyVetoException if one of listeners vetoes the property update
+ */
+ public void fireVetoableChange(PropertyChangeEvent event)
+ throws PropertyVetoException {
+ Object oldValue = event.getOldValue();
+ Object newValue = event.getNewValue();
+ if (oldValue == null || newValue == null || !oldValue.equals(newValue)) {
+ String name = event.getPropertyName();
+
+ VetoableChangeListener[] common = this.map.get(null);
+ VetoableChangeListener[] named = (name != null)
+ ? this.map.get(name)
+ : null;
+
+ VetoableChangeListener[] listeners;
+ if (common == null) {
+ listeners = named;
+ }
+ else if (named == null) {
+ listeners = common;
+ }
+ else {
+ listeners = new VetoableChangeListener[common.length + named.length];
+ System.arraycopy(common, 0, listeners, 0, common.length);
+ System.arraycopy(named, 0, listeners, common.length, named.length);
+ }
+ if (listeners != null) {
+ int current = 0;
+ try {
+ while (current < listeners.length) {
+ listeners[current].vetoableChange(event);
+ current++;
+ }
+ }
+ catch (PropertyVetoException veto) {
+ event = new PropertyChangeEvent(this.source, name, newValue, oldValue);
+ for (int i = 0; i < current; i++) {
+ try {
+ listeners[i].vetoableChange(event);
+ }
+ catch (PropertyVetoException exception) {
+ // ignore exceptions that occur during rolling back
+ }
+ }
+ throw veto; // rethrow the veto exception
+ }
+ }
+ }
+ }
+
+ /**
+ * Check if there are any listeners for a specific property, including
+ * those registered on all properties. If propertyName
+ * is null, only check for listeners registered on all properties.
+ *
+ * @param propertyName the property name.
+ * @return true if there are one or more listeners for the given property
+ */
+ public boolean hasListeners(String propertyName) {
+ return this.map.hasListeners(propertyName);
+ }
+
+ /**
+ * @serialData Null terminated list of VetoableChangeListeners.
+ *
+ * At serialization time we skip non-serializable listeners and
+ * only serialize the serializable listeners.
+ */
+ private void writeObject(ObjectOutputStream s) throws IOException {
+ Hashtable