| /* java.beans.beancontext.BeanContextChildSupport |
| Copyright (C) 1999 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.beancontext; |
| |
| import java.beans.PropertyChangeEvent; |
| import java.beans.PropertyChangeListener; |
| import java.beans.PropertyChangeSupport; |
| import java.beans.PropertyVetoException; |
| import java.beans.VetoableChangeListener; |
| import java.beans.VetoableChangeSupport; |
| import java.io.Serializable; |
| |
| /** |
| * Support for creating a <code>BeanContextChild</code>. |
| * This class contains the most common implementations of the methods in |
| * the <code>BeanContextChild</code> |
| * |
| * @specnote This class is not very well specified. I had to "fill in the |
| * blanks" in most places with what I thought was reasonable |
| * behavior. If there are problems, let me know. |
| * |
| * @author John Keiser |
| * @since 1.2 |
| * @see java.beans.beancontext.BeanContextChild |
| */ |
| public class BeanContextChildSupport |
| implements BeanContextChild, BeanContextServicesListener, Serializable |
| { |
| static final long serialVersionUID = 6328947014421475877L; |
| |
| /** |
| * The peer on which to perform <code>set</code> actions. |
| * This is here so that this class can be used as a peer. |
| * <P> |
| * |
| * When extending this class, this variable will be set to |
| * <code>this</code>. |
| */ |
| public BeanContextChild beanContextChildPeer; |
| |
| /** |
| * The parent <code>BeanContext</code>. |
| */ |
| protected transient BeanContext beanContext; |
| |
| /** |
| * If <code>setBeanContext()</code> was vetoed once before, this |
| * is set to <code>true</code> so that the next time, vetoes will |
| * be ignored. |
| */ |
| protected transient boolean rejectedSetBCOnce; |
| |
| /** |
| * Listeners are registered here and events are fired through here. |
| */ |
| protected PropertyChangeSupport pcSupport; |
| |
| /** |
| * Listeners are registered here and events are fired through here. |
| */ |
| protected VetoableChangeSupport vcSupport; |
| |
| /** |
| * Create a new <code>BeanContextChildSupport</code> with itself as the peer. |
| * This is meant to be used when you subclass |
| * <code>BeanContextChildSupport</code> to create your child. |
| */ |
| public BeanContextChildSupport() |
| { |
| this (null); |
| } |
| |
| /** |
| * Create a new <code>BeanContextChildSupport</code> with the specified peer. |
| * @param peer the peer to use, or <code>null</code> to specify |
| * <code>this</code>. |
| */ |
| public BeanContextChildSupport (BeanContextChild peer) |
| { |
| if (peer == null) |
| { |
| peer = this; |
| } |
| |
| beanContextChildPeer = peer; |
| pcSupport = new PropertyChangeSupport (peer); |
| vcSupport = new VetoableChangeSupport (peer); |
| } |
| |
| /** |
| * Set the parent <code>BeanContext</code>. |
| * <P> |
| * |
| * When this Object is being added to a new BeanContext or moved |
| * from an old one, a non-null value will be passed in. |
| * <P> |
| * |
| * When this Object is being removed from the current |
| * <code>BeanContext</code>, <code>setBeanContext()</code> will |
| * receive the parameter <code>null</code>. |
| * <P> |
| * |
| * Order of events: |
| * <OL> |
| * <LI> |
| * If the new <code>BeanContext</code> is the same as the old |
| * one, nothing happens. |
| * </LI> |
| * <LI> |
| * If the change has not been rejected or vetoed before, call |
| * <code>validatePendingSetBeanContext()</code>. If this call |
| * returns <code>false</code>, the change is rejected and a |
| * <code>PropertyVetoException</code> is thrown. |
| * </LI> |
| * <LI> |
| * If the change has not been rejected or vetoed before, |
| * <code>VetoableChangeEvent</code>s are fired with the name |
| * <code>"beanContext"</code>, using the |
| * <code>fireVetoableChange()</code> method. If a veto |
| * occurs, reversion events are fired using the same method, |
| * the change is rejected, and the veto is rethrown. |
| * </LI> |
| * <LI> |
| * <code>releaseBeanContextResources()</code> is called. |
| * </LI> |
| * <LI> |
| * The change is made. |
| * </LI> |
| * <LI> |
| * <code>PropertyChangeEvent</code>s are fired using the |
| * <code>firePropertyChange()</code> method. |
| * </LI> |
| * <LI> |
| * <code>initializeBeanContextResources()</code> is called. |
| * </LI> |
| * </OL> |
| * <P> |
| * |
| * @param newBeanContext the new parent for the |
| * <code>BeanContextChild</code>, or <code>null</code> to |
| * signify removal from a tree. |
| * @exception PropertyVetoException if the |
| * <code>BeanContextChild</code> implementor does not |
| * wish to have its parent changed. |
| */ |
| public void setBeanContext(BeanContext newBeanContext) |
| throws PropertyVetoException |
| { |
| synchronized (beanContextChildPeer) |
| { |
| if (newBeanContext == beanContext) |
| return; |
| |
| if (!rejectedSetBCOnce) |
| { |
| if (!validatePendingSetBeanContext (newBeanContext)) |
| { |
| rejectedSetBCOnce = true; |
| throw new PropertyVetoException ("validatePendingSetBeanContext() rejected change", |
| new PropertyChangeEvent(beanContextChildPeer, "beanContext", beanContext, newBeanContext)); |
| } |
| |
| try |
| { |
| fireVetoableChange ("beanContext", beanContext, newBeanContext); |
| } |
| catch (PropertyVetoException e) |
| { |
| rejectedSetBCOnce = true; |
| throw e; |
| } |
| } |
| |
| releaseBeanContextResources (); |
| |
| beanContext = newBeanContext; |
| rejectedSetBCOnce = false; |
| |
| firePropertyChange ("beanContext", beanContext, newBeanContext); |
| |
| initializeBeanContextResources (); |
| } |
| } |
| |
| /** |
| * Get the parent <code>BeanContext</code>. |
| * @return the parent <code>BeanContext</code>. |
| */ |
| public BeanContext getBeanContext() |
| { |
| return beanContext; |
| } |
| |
| /** |
| * Get the peer (or <code>this</code> if there is no peer). |
| * @return the peer, or <code>this</code> if there is no peer. |
| */ |
| public BeanContextChild getBeanContextChildPeer() { |
| return beanContextChildPeer; |
| } |
| |
| /** |
| * Determine whether there is a peer. |
| * This is true iff <code>getBeanContextChildPeer() == this</code>. |
| * @return whether there is a peer. |
| */ |
| public boolean isDelegated() { |
| return beanContextChildPeer == this; |
| } |
| |
| /** |
| * Add a listener that will be notified when a specific property changes. |
| * @param propertyName the name of the property to listen on. |
| * @param listener the listener to listen on the property. |
| */ |
| public void addPropertyChangeListener(String propertyName, PropertyChangeListener listener) { |
| pcSupport.addPropertyChangeListener(propertyName, listener); |
| } |
| |
| /** |
| * Remove a listener to a certain property. |
| * |
| * @param propertyName the name of the property being listened on. |
| * @param listener the listener listening on the property. |
| */ |
| public void removePropertyChangeListener(String propertyName, PropertyChangeListener listener) { |
| pcSupport.removePropertyChangeListener(propertyName, listener); |
| } |
| |
| /** |
| * Add a listener that will be notified when a specific property |
| * change is requested (a PropertyVetoException may be thrown) as |
| * well as after the change is successfully made. |
| * |
| * @param propertyName the name of the property to listen on. |
| * @param listener the listener to listen on the property. |
| */ |
| public void addVetoableChangeListener(String propertyName, VetoableChangeListener listener) { |
| vcSupport.addVetoableChangeListener(propertyName, listener); |
| } |
| |
| /** |
| * Remove a listener to a certain property. |
| * |
| * @param propertyName the name of the property being listened on |
| * @param listener the listener listening on the property. |
| */ |
| public void removeVetoableChangeListener(String propertyName, VetoableChangeListener listener) { |
| vcSupport.removeVetoableChangeListener(propertyName, listener); |
| } |
| |
| /** |
| * Fire a property change. |
| * |
| * @param propertyName the name of the property that changed |
| * @param oldVal the old value of the property |
| * @param newVal the new value of the property |
| */ |
| public void firePropertyChange(String propertyName, Object oldVal, Object newVal) { |
| pcSupport.firePropertyChange(propertyName, oldVal, newVal); |
| } |
| |
| /** |
| * Fire a vetoable property change. |
| * |
| * @param propertyName the name of the property that changed |
| * @param oldVal the old value of the property |
| * @param newVal the new value of the property |
| * @exception PropertyVetoException if the change is vetoed. |
| */ |
| public void fireVetoableChange(String propertyName, Object oldVal, Object newVal) |
| throws PropertyVetoException { |
| vcSupport.fireVetoableChange(propertyName, oldVal, newVal); |
| } |
| |
| /** |
| * Called by <code>BeanContextServices.revokeService()</code> to indicate that a service has been revoked. |
| * If you have a reference to such a service, it should be |
| * discarded and may no longer function properly. |
| * <code>getService()</code> will no longer work on the specified |
| * service class after this event has been fired. |
| * <P> |
| * |
| * <EM>This method is meant to be overriden.</EM> |
| * <code>BeanContextChildSupport</code>'s implementation does |
| * nothing. |
| * |
| * @param event the service revoked event. |
| * @see java.beans.beancontext.BeanContextServices#revokeService(java.lang.Class,java.beans.beancontext.BeanContextServiceProvider,boolean) |
| */ |
| public void serviceRevoked(BeanContextServiceRevokedEvent event) { |
| } |
| |
| /** |
| * Called by <code>BeanContextServices</code> whenever a service is made available. |
| * <P> |
| * |
| * <EM>This method is meant to be overriden.</EM> |
| * <code>BeanContextChildSupport</code>'s implementation does |
| * nothing. |
| * |
| * @param event the service revoked event, with useful information |
| * about the new service. |
| */ |
| public void serviceAvailable(BeanContextServiceAvailableEvent event) { |
| } |
| |
| /** |
| * Called by <code>setBeanContext()</code> to determine whether the set should be rejected. |
| * <P> |
| * |
| * <EM>This method is meant to be overriden.</EM> |
| * <code>BeanContextChildSupport</code>'s implementation simply |
| * returns <code>true</code>. |
| * |
| * @param newBeanContext the new parent. |
| * @return whether to allow the parent to be changed to the new |
| * value. |
| */ |
| public boolean validatePendingSetBeanContext(BeanContext newBeanContext) { |
| return true; |
| } |
| |
| /** |
| * Called by <code>setBeanContext()</code> to release resources of a what will soon no longer be the parent. |
| * <P> |
| * |
| * <EM>This method is meant to be overriden.</EM> |
| * <code>BeanContextChildSupport</code>'s implementation does |
| * nothing. |
| */ |
| protected void releaseBeanContextResources() { |
| } |
| |
| /** |
| * Called by <code>setBeanContext()</code> to grab resources when the parent has been set. |
| * <P> |
| * |
| * <EM>This method is meant to be overriden.</EM> |
| * <code>BeanContextChildSupport</code>'s implementation does |
| * nothing. |
| */ |
| protected void initializeBeanContextResources() { |
| } |
| } |