java.beans.beancontext

Class BeanContextChildSupport

public class BeanContextChildSupport extends Object implements BeanContextChild, BeanContextServicesListener, Serializable

Support for creating a BeanContextChild. This class contains the most common implementations of the methods in the BeanContextChild

Since: 1.2

See Also: BeanContextChild

UNKNOWN: 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.

Field Summary
protected BeanContext	beanContext The parent `BeanContext`.
BeanContextChild	beanContextChildPeer The peer on which to perform `set` actions.
protected PropertyChangeSupport	pcSupport Listeners are registered here and events are fired through here.
protected boolean	rejectedSetBCOnce If `setBeanContext()` was vetoed once before, this is set to `true` so that the next time, vetoes will be ignored.
protected VetoableChangeSupport	vcSupport Listeners are registered here and events are fired through here.

Constructor Summary
	BeanContextChildSupport() Create a new `BeanContextChildSupport` with itself as the peer.
	BeanContextChildSupport(BeanContextChild peer) Create a new `BeanContextChildSupport` with the specified peer.

Method Summary
void	addPropertyChangeListener(String propertyName, PropertyChangeListener listener) Add a listener that will be notified when a specific property changes.
void	addVetoableChangeListener(String propertyName, VetoableChangeListener 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.
void	firePropertyChange(String propertyName, Object oldVal, Object newVal) Fire a property change.
void	fireVetoableChange(String propertyName, Object oldVal, Object newVal) Fire a vetoable property change.
BeanContext	getBeanContext() Get the parent `BeanContext`.
BeanContextChild	getBeanContextChildPeer() Get the peer (or `this` if there is no peer).
protected void	initializeBeanContextResources() Called by `setBeanContext()` to grab resources when the parent has been set.
boolean	isDelegated() Determine whether there is a peer.
protected void	releaseBeanContextResources() Called by `setBeanContext()` to release resources of a what will soon no longer be the parent.
void	removePropertyChangeListener(String propertyName, PropertyChangeListener listener) Remove a listener to a certain property.
void	removeVetoableChangeListener(String propertyName, VetoableChangeListener listener) Remove a listener to a certain property.
void	serviceAvailable(BeanContextServiceAvailableEvent event) Called by `BeanContextServices` whenever a service is made available.
void	serviceRevoked(BeanContextServiceRevokedEvent event) Called by `BeanContextServices.revokeService()` to indicate that a service has been revoked.
void	setBeanContext(BeanContext newBeanContext) Set the parent `BeanContext`.
boolean	validatePendingSetBeanContext(BeanContext newBeanContext) Called by `setBeanContext()` to determine whether the set should be rejected.

Field Detail

beanContext

protected transient BeanContext beanContext

The parent BeanContext.

beanContextChildPeer

public BeanContextChild beanContextChildPeer

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.

pcSupport

protected PropertyChangeSupport pcSupport

Listeners are registered here and events are fired through here.

rejectedSetBCOnce

protected transient boolean rejectedSetBCOnce

If setBeanContext() was vetoed once before, this is set to true so that the next time, vetoes will be ignored.

vcSupport

protected VetoableChangeSupport vcSupport

Listeners are registered here and events are fired through here.

Constructor Detail

BeanContextChildSupport

public BeanContextChildSupport()

Create a new BeanContextChildSupport with itself as the peer. This is meant to be used when you subclass BeanContextChildSupport to create your child.

BeanContextChildSupport

public BeanContextChildSupport(BeanContextChild peer)

Create a new BeanContextChildSupport with the specified peer.

Parameters: peer the peer to use, or null to specify this.

Method Detail

addPropertyChangeListener

public void addPropertyChangeListener(String propertyName, PropertyChangeListener listener)

Add a listener that will be notified when a specific property changes.

Parameters: propertyName the name of the property to listen on. listener the listener to listen on the property.

addVetoableChangeListener

public void addVetoableChangeListener(String propertyName, VetoableChangeListener 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.

Parameters: propertyName the name of the property to listen on. listener the listener to listen on the property.

firePropertyChange

public void firePropertyChange(String propertyName, Object oldVal, Object newVal)

Fire a property change.

Parameters: propertyName the name of the property that changed oldVal the old value of the property newVal the new value of the property

fireVetoableChange

public void fireVetoableChange(String propertyName, Object oldVal, Object newVal)

Fire a vetoable property change.

Parameters: propertyName the name of the property that changed oldVal the old value of the property newVal the new value of the property

Throws: PropertyVetoException if the change is vetoed.

getBeanContext

public BeanContext getBeanContext()

Get the parent BeanContext.

Returns: the parent BeanContext.

getBeanContextChildPeer

public BeanContextChild getBeanContextChildPeer()

Get the peer (or this if there is no peer).

Returns: the peer, or this if there is no peer.

initializeBeanContextResources

protected void initializeBeanContextResources()

Called by setBeanContext() to grab resources when the parent has been set.

This method is meant to be overriden. BeanContextChildSupport's implementation does nothing.

isDelegated

public boolean isDelegated()

Determine whether there is a peer. This is true iff getBeanContextChildPeer() == this.

Returns: whether there is a peer.

releaseBeanContextResources

protected void releaseBeanContextResources()

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.

removePropertyChangeListener

public void removePropertyChangeListener(String propertyName, PropertyChangeListener listener)

Remove a listener to a certain property.

Parameters: propertyName the name of the property being listened on. listener the listener listening on the property.

removeVetoableChangeListener

public void removeVetoableChangeListener(String propertyName, VetoableChangeListener listener)

Remove a listener to a certain property.

Parameters: propertyName the name of the property being listened on listener the listener listening on the property.

serviceAvailable

public void serviceAvailable(BeanContextServiceAvailableEvent event)

Called by BeanContextServices whenever a service is made available.

This method is meant to be overriden. BeanContextChildSupport's implementation does nothing.

Parameters: event the service revoked event, with useful information about the new service.

serviceRevoked

public void serviceRevoked(BeanContextServiceRevokedEvent event)

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.

Parameters: event the service revoked event.

setBeanContext

public void setBeanContext(BeanContext newBeanContext)

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:

If the new BeanContext is the same as the old one, nothing happens.
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.
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.
releaseBeanContextResources() is called.
The change is made.
PropertyChangeEvents are fired using the firePropertyChange() method.
initializeBeanContextResources() is called.

Parameters: newBeanContext the new parent for the BeanContextChild, or null to signify removal from a tree.

Throws: PropertyVetoException if the BeanContextChild implementor does not wish to have its parent changed.

validatePendingSetBeanContext

public boolean validatePendingSetBeanContext(BeanContext newBeanContext)

Called by setBeanContext() to determine whether the set should be rejected.

This method is meant to be overriden. BeanContextChildSupport's implementation simply returns true.

Parameters: newBeanContext the new parent.

Returns: whether to allow the parent to be changed to the new value.