| /* |
| * Copyright (c) 1999, 2017, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code 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 |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| package javax.swing; |
| |
| import java.beans.PropertyChangeEvent; |
| import java.beans.PropertyChangeListener; |
| import java.io.*; |
| import java.lang.ref.WeakReference; |
| import java.lang.ref.ReferenceQueue; |
| |
| /** |
| * A package-private PropertyChangeListener which listens for |
| * property changes on an Action and updates the properties |
| * of an ActionEvent source. |
| * <p> |
| * Subclasses must override the actionPropertyChanged method, |
| * which is invoked from the propertyChange method as long as |
| * the target is still valid. |
| * </p> |
| * <p> |
| * WARNING WARNING WARNING WARNING WARNING WARNING:<br> |
| * Do NOT create an annonymous inner class that extends this! If you do |
| * a strong reference will be held to the containing class, which in most |
| * cases defeats the purpose of this class. |
| * |
| * @param <T> the type of JComponent the underlying Action is attached to |
| * |
| * @author Georges Saab |
| * @see AbstractButton |
| */ |
| @SuppressWarnings("serial") // Bound of type variable is not serializable across versions |
| abstract class ActionPropertyChangeListener<T extends JComponent> |
| implements PropertyChangeListener, Serializable { |
| private static ReferenceQueue<JComponent> queue; |
| |
| // WeakReference's aren't serializable. |
| private transient OwnedWeakReference<T> target; |
| // The Component's that reference an Action do so through a strong |
| // reference, so that there is no need to check for serialized. |
| private Action action; |
| |
| private static ReferenceQueue<JComponent> getQueue() { |
| synchronized(ActionPropertyChangeListener.class) { |
| if (queue == null) { |
| queue = new ReferenceQueue<JComponent>(); |
| } |
| } |
| return queue; |
| } |
| |
| public ActionPropertyChangeListener(T c, Action a) { |
| super(); |
| setTarget(c); |
| this.action = a; |
| } |
| |
| /** |
| * PropertyChangeListener method. If the target has been gc'ed this |
| * will remove the <code>PropertyChangeListener</code> from the Action, |
| * otherwise this will invoke actionPropertyChanged. |
| */ |
| public final void propertyChange(PropertyChangeEvent e) { |
| T target = getTarget(); |
| if (target == null) { |
| getAction().removePropertyChangeListener(this); |
| } else { |
| actionPropertyChanged(target, getAction(), e); |
| } |
| } |
| |
| /** |
| * Invoked when a property changes on the Action and the target |
| * still exists. |
| */ |
| protected abstract void actionPropertyChanged(T target, Action action, |
| PropertyChangeEvent e); |
| |
| private void setTarget(T c) { |
| ReferenceQueue<JComponent> queue = getQueue(); |
| // Check to see whether any old buttons have |
| // been enqueued for GC. If so, look up their |
| // PCL instance and remove it from its Action. |
| OwnedWeakReference<?> r; |
| while ((r = (OwnedWeakReference)queue.poll()) != null) { |
| ActionPropertyChangeListener<?> oldPCL = r.getOwner(); |
| Action oldAction = oldPCL.getAction(); |
| if (oldAction!=null) { |
| oldAction.removePropertyChangeListener(oldPCL); |
| } |
| } |
| this.target = new OwnedWeakReference<T>(c, queue, this); |
| } |
| |
| public T getTarget() { |
| if (target == null) { |
| // Will only happen if serialized and real target was null |
| return null; |
| } |
| return this.target.get(); |
| } |
| |
| public Action getAction() { |
| return action; |
| } |
| |
| private void writeObject(ObjectOutputStream s) throws IOException { |
| s.defaultWriteObject(); |
| s.writeObject(getTarget()); |
| } |
| |
| @SuppressWarnings("unchecked") |
| private void readObject(ObjectInputStream s) |
| throws IOException, ClassNotFoundException { |
| s.defaultReadObject(); |
| T target = (T)s.readObject(); |
| if (target != null) { |
| setTarget(target); |
| } |
| } |
| |
| |
| private static class OwnedWeakReference<U extends JComponent> extends |
| WeakReference<U> { |
| private ActionPropertyChangeListener<?> owner; |
| |
| OwnedWeakReference(U target, ReferenceQueue<? super U> queue, |
| ActionPropertyChangeListener<?> owner) { |
| super(target, queue); |
| this.owner = owner; |
| } |
| |
| public ActionPropertyChangeListener<?> getOwner() { |
| return owner; |
| } |
| } |
| } |