/* 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 BeanContextChild. * This class contains the most common implementations of the methods in * the BeanContextChild * * @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 set actions. * This is here so that this class can be used as a peer. *

* * When extending this class, this variable will be set to * this. */ public BeanContextChild beanContextChildPeer; /** * The parent BeanContext. */ protected transient BeanContext beanContext; /** * If setBeanContext() was vetoed once before, this * is set to true 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 BeanContextChildSupport with itself as the peer. * This is meant to be used when you subclass * BeanContextChildSupport to create your child. */ public BeanContextChildSupport() { this (null); } /** * Create a new BeanContextChildSupport with the specified peer. * @param peer the peer to use, or null to specify * this. */ public BeanContextChildSupport (BeanContextChild peer) { if (peer == null) { peer = this; } beanContextChildPeer = peer; pcSupport = new PropertyChangeSupport (peer); vcSupport = new VetoableChangeSupport (peer); } /** * Set the parent BeanContext. *

* * When this Object is being added to a new BeanContext or moved * from an old one, a non-null value will be passed in. *

* * When this Object is being removed from the current * BeanContext, setBeanContext() will * receive the parameter null. *

* * Order of events: *

    *
  1. * If the new BeanContext is the same as the old * one, nothing happens. *
    2. *
  2. * If the change has not been rejected or vetoed before, call * validatePendingSetBeanContext(). If this call * returns false, the change is rejected and a * PropertyVetoException is thrown. *
    3. *
  3. * If the change has not been rejected or vetoed before, * VetoableChangeEvents are fired with the name * "beanContext", using the * fireVetoableChange() method. If a veto * occurs, reversion events are fired using the same method, * the change is rejected, and the veto is rethrown. *
    4. *
  4. * releaseBeanContextResources() is called. *
    5. *
  5. * The change is made. *
    6. *
  6. * PropertyChangeEvents are fired using the * firePropertyChange() method. *
    7. *
  7. * initializeBeanContextResources() is called. *
    8. *
*

* * @param newBeanContext the new parent for the * BeanContextChild, or null to * signify removal from a tree. * @exception PropertyVetoException if the * BeanContextChild 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 BeanContext. * @return the parent BeanContext. */ public BeanContext getBeanContext() { return beanContext; } /** * Get the peer (or this if there is no peer). * @return the peer, or this if there is no peer. */ public BeanContextChild getBeanContextChildPeer() { return beanContextChildPeer; } /** * Determine whether there is a peer. * This is true iff getBeanContextChildPeer() == this. * @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 BeanContextServices.revokeService() 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. * getService() will no longer work on the specified * service class after this event has been fired. *

* * This method is meant to be overriden. * BeanContextChildSupport'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 BeanContextServices whenever a service is made available. *

* * This method is meant to be overriden. * BeanContextChildSupport's implementation does * nothing. * * @param event the service revoked event, with useful information * about the new service. */ public void serviceAvailable(BeanContextServiceAvailableEvent event) { } /** * Called by setBeanContext() to determine whether the set should be rejected. *

* * This method is meant to be overriden. * BeanContextChildSupport's implementation simply * returns true. * * @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 setBeanContext() to release resources of a what will soon no longer be the parent. *

* * This method is meant to be overriden. * BeanContextChildSupport's implementation does * nothing. */ protected void releaseBeanContextResources() { } /** * Called by setBeanContext() to grab resources when the parent has been set. *

* * This method is meant to be overriden. * BeanContextChildSupport's implementation does * nothing. */ protected void initializeBeanContextResources() { } }