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Diffstat (limited to 'libjava/classpath/java/beans/beancontext/BeanContextChildSupport.java')
| -rw-r--r-- | libjava/classpath/java/beans/beancontext/BeanContextChildSupport.java | 381 |
1 files changed, 381 insertions, 0 deletions
diff --git a/libjava/classpath/java/beans/beancontext/BeanContextChildSupport.java b/libjava/classpath/java/beans/beancontext/BeanContextChildSupport.java new file mode 100644 index 000000000..8cd887d0c --- /dev/null +++ b/libjava/classpath/java/beans/beancontext/BeanContextChildSupport.java @@ -0,0 +1,381 @@ +/* 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() { + } +} |