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authorupstream source tree <ports@midipix.org>2015-03-15 20:14:05 -0400
committerupstream source tree <ports@midipix.org>2015-03-15 20:14:05 -0400
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tree976dc5ab7fddf506dadce60ae936f43f58787092 /libjava/classpath/java/beans/VetoableChangeSupport.java
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+/* VetoableChangeSupport.java -- support to manage vetoable change listeners
+ Copyright (C) 1998, 1999, 2000, 2002, 2005, 2006,
+ 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. This method will unwrap a VetoableChangeListenerProxy,
+ * registering the underlying delegate to the named property list.
+ *
+ * @param l the listener to add (<code>null</code> ignored).
+ */
+ public synchronized void addVetoableChangeListener(VetoableChangeListener l)
+ {
+ if (l == null)
+ return;
+ 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. 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
+ */
+ public synchronized void addVetoableChangeListener(String propertyName,
+ VetoableChangeListener l)
+ {
+ if (propertyName == null || l == 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();
+ }
+ 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,
+ Integer.valueOf(oldVal),
+ Integer.valueOf(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