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Diffstat (limited to 'libjava/classpath/java/beans/VetoableChangeSupport.java')
| -rw-r--r-- | libjava/classpath/java/beans/VetoableChangeSupport.java | 530 |
1 files changed, 530 insertions, 0 deletions
diff --git a/libjava/classpath/java/beans/VetoableChangeSupport.java b/libjava/classpath/java/beans/VetoableChangeSupport.java new file mode 100644 index 00000000000..dce8dffd341 --- /dev/null +++ b/libjava/classpath/java/beans/VetoableChangeSupport.java @@ -0,0 +1,530 @@ +/* VetoableChangeSupport.java -- support to manage vetoable change listeners + Copyright (C) 1998, 1999, 2000, 2002, 2005 Free Software Foundation, Inc. + +This file is part of GNU Classpath. + +GNU Classpath is free software; you can redistribute it and/or modify +it under the terms of the GNU General Public License as published by +the Free Software Foundation; either version 2, or (at your option) +any later version. + +GNU Classpath is distributed in the hope that it will be useful, but +WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +General Public License for more details. + +You should have received a copy of the GNU General Public License +along with GNU Classpath; see the file COPYING. If not, write to the +Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA +02110-1301 USA. + +Linking this library statically or dynamically with other modules is +making a combined work based on this library. Thus, the terms and +conditions of the GNU General Public License cover the whole +combination. + +As a special exception, the copyright holders of this library give you +permission to link this library with independent modules to produce an +executable, regardless of the license terms of these independent +modules, and to copy and distribute the resulting executable under +terms of your choice, provided that you also meet, for each linked +independent module, the terms and conditions of the license of that +module. An independent module is a module which is not derived from +or based on this library. If you modify this library, you may extend +this exception to your version of the library, but you are not +obligated to do so. If you do not wish to do so, delete this +exception statement from your version. */ + + +package java.beans; + +import java.io.IOException; +import java.io.ObjectInputStream; +import java.io.ObjectOutputStream; +import java.io.Serializable; +import java.util.ArrayList; +import java.util.Arrays; +import java.util.Hashtable; +import java.util.Iterator; +import java.util.Map.Entry; +import java.util.Vector; + +/** + * VetoableChangeSupport makes it easy to fire vetoable change events and + * handle listeners. It allows chaining of listeners, as well as filtering + * by property name. In addition, it will serialize only those listeners + * which are serializable, ignoring the others without problem. This class + * is thread-safe. + * + * @author John Keiser + * @author Eric Blake (ebb9@email.byu.edu) + * @since 1.1 + * @status updated to 1.4 + */ +public class VetoableChangeSupport implements Serializable +{ + /** + * Compatible with JDK 1.1+. + */ + private static final long serialVersionUID = -5090210921595982017L; + + /** + * Maps property names (String) to named listeners (VetoableChangeSupport). + * If this is a child instance, this field will be null. + * + * @serial the map of property names to named listener managers + * @since 1.2 + */ + private Hashtable children; + + /** + * The non-null source object for any generated events. + * + * @serial the event source + */ + private final Object source; + + /** + * A field to compare serialization versions - this class uses version 2. + * + * @serial the serialization format + */ + private static final int vetoableChangeSupportSerializedDataVersion = 2; + + /** + * The list of all registered vetoable listeners. If this instance was + * created by user code, this only holds the global listeners (ie. not tied + * to a name), and may be null. If it was created by this class, as a + * helper for named properties, then this vector will be non-null, and this + * instance appears as a value in the <code>children</code> hashtable of + * another instance, so that the listeners are tied to the key of that + * hashtable entry. + */ + private transient Vector listeners; + + /** + * Create a VetoableChangeSupport to work with a specific source bean. + * + * @param source the source bean to use + * @throws NullPointerException if source is null + */ + public VetoableChangeSupport(Object source) + { + this.source = source; + if (source == null) + throw new NullPointerException(); + } + + /** + * Adds a VetoableChangeListener to the list of global listeners. All + * vetoable change events will be sent to this listener. The listener add + * is not unique: that is, <em>n</em> adds with the same listener will + * result in <em>n</em> events being sent to that listener for every + * vetoable change. Adding a null listener may cause a NullPointerException + * down the road. This method will unwrap a VetoableChangeListenerProxy, + * registering the underlying delegate to the named property list. + * + * @param l the listener to add + */ + public synchronized void addVetoableChangeListener(VetoableChangeListener l) + { + if (l instanceof VetoableChangeListenerProxy) + { + VetoableChangeListenerProxy p = (VetoableChangeListenerProxy) l; + addVetoableChangeListener(p.propertyName, + (VetoableChangeListener) p.getListener()); + } + else + { + if (listeners == null) + listeners = new Vector(); + listeners.add(l); + } + } + + /** + * Removes a VetoableChangeListener from the list of global listeners. If + * any specific properties are being listened on, they must be deregistered + * by themselves; this will only remove the general listener to all + * properties. If <code>add()</code> has been called multiple times for a + * particular listener, <code>remove()</code> will have to be called the + * same number of times to deregister it. This method will unwrap a + * VetoableChangeListenerProxy, removing the underlying delegate from the + * named property list. + * + * @param l the listener to remove + */ + public synchronized void + removeVetoableChangeListener(VetoableChangeListener l) + { + if (l instanceof VetoableChangeListenerProxy) + { + VetoableChangeListenerProxy p = (VetoableChangeListenerProxy) l; + removeVetoableChangeListener(p.propertyName, + (VetoableChangeListener) p.getListener()); + } + else if (listeners != null) + { + listeners.remove(l); + if (listeners.isEmpty()) + listeners = null; + } + } + + /** + * Returns an array of all registered vetoable change listeners. Those that + * were registered under a name will be wrapped in a + * <code>VetoableChangeListenerProxy</code>, so you must check whether the + * listener is an instance of the proxy class in order to see what name the + * real listener is registered under. If there are no registered listeners, + * this returns an empty array. + * + * @return the array of registered listeners + * @see VetoableChangeListenerProxy + * @since 1.4 + */ + public synchronized VetoableChangeListener[] getVetoableChangeListeners() + { + ArrayList list = new ArrayList(); + if (listeners != null) + list.addAll(listeners); + if (children != null) + { + int i = children.size(); + Iterator iter = children.entrySet().iterator(); + while (--i >= 0) + { + Entry e = (Entry) iter.next(); + String name = (String) e.getKey(); + Vector v = ((VetoableChangeSupport) e.getValue()).listeners; + int j = v.size(); + while (--j >= 0) + list.add(new VetoableChangeListenerProxy + (name, (VetoableChangeListener) v.get(j))); + } + } + return (VetoableChangeListener[]) + list.toArray(new VetoableChangeListener[list.size()]); + } + + /** + * Adds a VetoableChangeListener listening on the specified property. Events + * will be sent to the listener only if the property name matches. The + * listener add is not unique; that is, <em>n</em> adds on a particular + * property for a particular listener will result in <em>n</em> events + * being sent to that listener when that property is changed. The effect is + * cumulative, too; if you are registered to listen to receive events on + * all vetoable changes, and then you register on a particular property, + * you will receive change events for that property twice. Adding a null + * listener may cause a NullPointerException down the road. This method + * will unwrap a VetoableChangeListenerProxy, registering the underlying + * delegate to the named property list if the names match, and discarding + * it otherwise. + * + * @param propertyName the name of the property to listen on + * @param l the listener to add + * @throws NullPointerException if propertyName is null + */ + public synchronized void addVetoableChangeListener(String propertyName, + VetoableChangeListener l) + { + while (l instanceof VetoableChangeListenerProxy) + { + VetoableChangeListenerProxy p = (VetoableChangeListenerProxy) l; + if (propertyName == null ? p.propertyName != null + : ! propertyName.equals(p.propertyName)) + return; + l = (VetoableChangeListener) p.getListener(); + } + VetoableChangeSupport s = null; + if (children == null) + children = new Hashtable(); + else + s = (VetoableChangeSupport) children.get(propertyName); + if (s == null) + { + s = new VetoableChangeSupport(source); + s.listeners = new Vector(); + children.put(propertyName, s); + } + s.listeners.add(l); + } + + /** + * Removes a VetoableChangeListener from listening to a specific property. + * If <code>add()</code> has been called multiple times for a particular + * listener on a property, <code>remove()</code> will have to be called the + * same number of times to deregister it. This method will unwrap a + * VetoableChangeListenerProxy, removing the underlying delegate from the + * named property list if the names match. + * + * @param propertyName the property to stop listening on + * @param l the listener to remove + * @throws NullPointerException if propertyName is null + */ + public synchronized void + removeVetoableChangeListener(String propertyName, VetoableChangeListener l) + { + if (children == null) + return; + VetoableChangeSupport s + = (VetoableChangeSupport) children.get(propertyName); + if (s == null) + return; + while (l instanceof VetoableChangeListenerProxy) + { + VetoableChangeListenerProxy p = (VetoableChangeListenerProxy) l; + if (propertyName == null ? p.propertyName != null + : ! propertyName.equals(p.propertyName)) + return; + l = (VetoableChangeListener) p.getListener(); + } + s.listeners.remove(l); + if (s.listeners.isEmpty()) + { + children.remove(propertyName); + if (children.isEmpty()) + children = null; + } + } + + /** + * Returns an array of all vetoable change listeners registered under the + * given property name. If there are no registered listeners, this returns + * an empty array. + * + * @return the array of registered listeners + * @throws NullPointerException if propertyName is null + * @since 1.4 + */ + public synchronized VetoableChangeListener[] + getVetoableChangeListeners(String propertyName) + { + if (children == null) + return new VetoableChangeListener[0]; + VetoableChangeSupport s + = (VetoableChangeSupport) children.get(propertyName); + if (s == null) + return new VetoableChangeListener[0]; + return (VetoableChangeListener[]) + s.listeners.toArray(new VetoableChangeListener[s.listeners.size()]); + } + + /** + * Fire a PropertyChangeEvent containing the old and new values of the + * property to all the global listeners, and to all the listeners for the + * specified property name. This does nothing if old and new are non-null + * and equal. If the change is vetoed, a new event is fired to notify + * listeners about the rollback before the exception is thrown. + * + * @param propertyName the name of the property that changed + * @param oldVal the old value + * @param newVal the new value + * @throws PropertyVetoException if the change is vetoed by a listener + */ + public void fireVetoableChange(String propertyName, + Object oldVal, Object newVal) + throws PropertyVetoException + { + fireVetoableChange(new PropertyChangeEvent(source, propertyName, + oldVal, newVal)); + } + + /** + * Fire a PropertyChangeEvent containing the old and new values of the + * property to all the global listeners, and to all the listeners for the + * specified property name. This does nothing if old and new are equal. + * If the change is vetoed, a new event is fired to notify listeners about + * the rollback before the exception is thrown. + * + * @param propertyName the name of the property that changed + * @param oldVal the old value + * @param newVal the new value + * @throws PropertyVetoException if the change is vetoed by a listener + */ + public void fireVetoableChange(String propertyName, int oldVal, int newVal) + throws PropertyVetoException + { + if (oldVal != newVal) + fireVetoableChange(new PropertyChangeEvent(source, propertyName, + new Integer(oldVal), + new Integer(newVal))); + } + + /** + * Fire a PropertyChangeEvent containing the old and new values of the + * property to all the global listeners, and to all the listeners for the + * specified property name. This does nothing if old and new are equal. + * If the change is vetoed, a new event is fired to notify listeners about + * the rollback before the exception is thrown. + * + * @param propertyName the name of the property that changed + * @param oldVal the old value + * @param newVal the new value + * @throws PropertyVetoException if the change is vetoed by a listener + */ + public void fireVetoableChange(String propertyName, + boolean oldVal, boolean newVal) + throws PropertyVetoException + { + if (oldVal != newVal) + fireVetoableChange(new PropertyChangeEvent(source, propertyName, + Boolean.valueOf(oldVal), + Boolean.valueOf(newVal))); + } + + /** + * Fire a PropertyChangeEvent to all the global listeners, and to all the + * listeners for the specified property name. This does nothing if old and + * new values of the event are equal. If the change is vetoed, a new event + * is fired to notify listeners about the rollback before the exception is + * thrown. + * + * @param event the event to fire + * @throws NullPointerException if event is null + * @throws PropertyVetoException if the change is vetoed by a listener + */ + public void fireVetoableChange(PropertyChangeEvent event) + throws PropertyVetoException + { + if (event.oldValue != null && event.oldValue.equals(event.newValue)) + return; + Vector v = listeners; // Be thread-safe. + if (v != null) + { + int i = v.size(); + try + { + while (--i >= 0) + ((VetoableChangeListener) v.get(i)).vetoableChange(event); + } + catch (PropertyVetoException e) + { + event = event.rollback(); + int limit = i; + i = v.size(); + while (--i >= limit) + ((VetoableChangeListener) v.get(i)).vetoableChange(event); + throw e; + } + } + Hashtable h = children; // Be thread-safe. + if (h != null && event.propertyName != null) + { + VetoableChangeSupport s + = (VetoableChangeSupport) h.get(event.propertyName); + if (s != null) + { + Vector v1 = s.listeners; // Be thread-safe. + int i = v1 == null ? 0 : v1.size(); + try + { + while (--i >= 0) + ((VetoableChangeListener) v1.get(i)).vetoableChange(event); + } + catch (PropertyVetoException e) + { + event = event.rollback(); + int limit = i; + i = v.size(); + while (--i >= 0) + ((VetoableChangeListener) v.get(i)).vetoableChange(event); + i = v1.size(); + while (--i >= limit) + ((VetoableChangeListener) v1.get(i)).vetoableChange(event); + throw e; + } + } + } + } + + /** + * Tell whether the specified property is being listened on or not. This + * will only return <code>true</code> if there are listeners on all + * properties or if there is a listener specifically on this property. + * + * @param propertyName the property that may be listened on + * @return whether the property is being listened on + * @throws NullPointerException if propertyName is null + */ + public synchronized boolean hasListeners(String propertyName) + { + return listeners != null || (children != null + && children.get(propertyName) != null); + } + + /** + * Saves the state of the object to the stream. + * + * @param s the stream to write to + * @throws IOException if anything goes wrong + * @serialData this writes out a null-terminated list of serializable + * global vetoable change listeners (the listeners for a named + * property are written out as the global listeners of the + * children, when the children hashtable is saved) + */ + private synchronized void writeObject(ObjectOutputStream s) + throws IOException + { + s.defaultWriteObject(); + if (listeners != null) + { + int i = listeners.size(); + while (--i >= 0) + if (listeners.get(i) instanceof Serializable) + s.writeObject(listeners.get(i)); + } + s.writeObject(null); + } + + /** + * Reads the object back from stream (deserialization). + * + * XXX Since serialization for 1.1 streams was not documented, this may + * not work if vetoableChangeSupportSerializedDataVersion is 1. + * + * @param s the stream to read from + * @throws IOException if reading the stream fails + * @throws ClassNotFoundException if deserialization fails + * @serialData this reads in a null-terminated list of serializable + * global vetoable change listeners (the listeners for a named + * property are written out as the global listeners of the + * children, when the children hashtable is saved) + */ + private void readObject(ObjectInputStream s) + throws IOException, ClassNotFoundException + { + s.defaultReadObject(); + VetoableChangeListener l = (VetoableChangeListener) s.readObject(); + while (l != null) + { + addVetoableChangeListener(l); + l = (VetoableChangeListener) s.readObject(); + } + // Sun is not as careful with children as we are, and lets some proxys + // in that can never receive events. So, we clean up anything that got + // serialized, to make sure our invariants hold. + if (children != null) + { + int i = children.size(); + Iterator iter = children.entrySet().iterator(); + while (--i >= 0) + { + Entry e = (Entry) iter.next(); + String name = (String) e.getKey(); + VetoableChangeSupport vcs = (VetoableChangeSupport) e.getValue(); + if (vcs.listeners == null) + vcs.listeners = new Vector(); + if (vcs.children != null) + vcs.listeners.addAll + (Arrays.asList(vcs.getVetoableChangeListeners(name))); + if (vcs.listeners.size() == 0) + iter.remove(); + else + vcs.children = null; + } + if (children.size() == 0) + children = null; + } + } +} // class VetoableChangeSupport |