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 JDK1.2
- * @see java.beans.beancontext.BeanContextChild
- */
-
-public class BeanContextChildSupport implements BeanContextChild, BeanContextServicesListener, Serializable {
- /**
- * 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: - *
BeanContext is the same as the old
- * one, nothing happens.
- * validatePendingSetBeanContext(). If this call
- * returns false, the change is rejected and a
- * PropertyVetoException is thrown.
- * 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.
- * releaseBeanContextResources() is called.
- * PropertyChangeEvents are fired using the
- * firePropertyChange() method.
- * initializeBeanContextResources() is called.
- *
- *
- * @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() {
- }
-}