/*
* @(#)BeanContextChildSupport.java 1.16 04/03/04
*
* Copyright 2004 Sun Microsystems, Inc. All rights reserved.
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
package java.beans.beancontext;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.beans.PropertyChangeSupport;
import java.beans.VetoableChangeListener;
import java.beans.VetoableChangeSupport;
import java.beans.PropertyVetoException;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
/**
* <p>
* This is a general support class to provide support for implementing the
* BeanContextChild protocol.
*
* This class may either be directly subclassed, or encapsulated and delegated
* to in order to implement this interface for a given component.
* </p>
*
* @author Laurence P. G. Cable
* @version 1.16, 03/04/04
* @since 1.2
*
* @see java.beans.beancontext.BeanContext
* @see java.beans.beancontext.BeanContextServices
* @see java.beans.beancontext.BeanContextChild
*/
public class BeanContextChildSupport implements BeanContextChild, BeanContextServicesListener, Serializable {
static final long serialVersionUID = 6328947014421475877L;
/**
* construct a BeanContextChildSupport where this class has been
* subclassed in order to implement the JavaBean component itself.
*/
public BeanContextChildSupport() {
super();
beanContextChildPeer = this;
pcSupport = new PropertyChangeSupport(beanContextChildPeer);
vcSupport = new VetoableChangeSupport(beanContextChildPeer);
}
/**
* construct a BeanContextChildSupport where the JavaBean component
* itself implements BeanContextChild, and encapsulates this, delegating
* that interface to this implementation
*/
public BeanContextChildSupport(BeanContextChild bcc) {
super();
beanContextChildPeer = (bcc != null) ? bcc : this;
pcSupport = new PropertyChangeSupport(beanContextChildPeer);
vcSupport = new VetoableChangeSupport(beanContextChildPeer);
}
/**
* Sets the <code>BeanContext</code> for
* this <code>BeanContextChildSupport</code>.
* @param bc the new value to be assigned to the <code>BeanContext</code>
* property
* @throws <code>PropertyVetoException</code> if the change is rejected
*/
public synchronized void setBeanContext(BeanContext bc) throws PropertyVetoException {
if (bc == beanContext) return;
BeanContext oldValue = beanContext;
BeanContext newValue = bc;
if (!rejectedSetBCOnce) {
if (rejectedSetBCOnce = !validatePendingSetBeanContext(bc)) {
throw new PropertyVetoException(
"setBeanContext() change rejected:",
new PropertyChangeEvent(beanContextChildPeer, "beanContext", oldValue, newValue)
);
}
try {
fireVetoableChange("beanContext",
oldValue,
newValue
);
} catch (PropertyVetoException pve) {
rejectedSetBCOnce = true;
throw pve; // re-throw
}
}
if (beanContext != null) releaseBeanContextResources();
beanContext = newValue;
rejectedSetBCOnce = false;
firePropertyChange("beanContext",
oldValue,
newValue
);
if (beanContext != null) initializeBeanContextResources();
}
/**
* Gets the nesting <code>BeanContext</code>
* for this <code>BeanContextChildSupport</code>.
* @return the nesting <code>BeanContext</code> for
* this <code>BeanContextChildSupport</code>.
*/
public synchronized BeanContext getBeanContext() { return beanContext; }
/**
* Add a PropertyChangeListener for a specific property.
* The same listener object may be added more than once. For each
* property, the listener will be invoked the number of times it was added
* for that property.
* If <code>name</code> or <code>pcl</code> is null, no exception is thrown
* and no action is taken.
*
* @param name The name of the property to listen on
* @param pcl The <code>PropertyChangeListener</code> to be added
*/
public void addPropertyChangeListener(String name, PropertyChangeListener pcl) {
pcSupport.addPropertyChangeListener(name, pcl);
}
/**
* Remove a PropertyChangeListener for a specific property.
* If <code>pcl</code> was added more than once to the same event
* source for the specified property, it will be notified one less time
* after being removed.
* If <code>name</code> is null, no exception is thrown
* and no action is taken.
* If <code>pcl</code> is null, or was never added for the specified
* property, no exception is thrown and no action is taken.
*
* @param name The name of the property that was listened on
* @param pcl The PropertyChangeListener to be removed
*/
public void removePropertyChangeListener(String name, PropertyChangeListener pcl) {
pcSupport.removePropertyChangeListener(name, pcl);
}
/**
* Add a VetoableChangeListener for a specific property.
* The same listener object may be added more than once. For each
* property, the listener will be invoked the number of times it was added
* for that property.
* If <code>name</code> or <code>vcl</code> is null, no exception is thrown
* and no action is taken.
*
* @param name The name of the property to listen on
* @param vcl The <code>VetoableChangeListener</code> to be added
*/
public void addVetoableChangeListener(String name, VetoableChangeListener vcl) {
vcSupport.addVetoableChangeListener(name, vcl);
}
/**
* Removes a <code>VetoableChangeListener</code>.
* If <code>pcl</code> was added more than once to the same event
* source for the specified property, it will be notified one less time
* after being removed.
* If <code>name</code> is null, no exception is thrown
* and no action is taken.
* If <code>vcl</code> is null, or was never added for the specified
* property, no exception is thrown and no action is taken.
*
* @param name The name of the property that was listened on
* @param vcl The <code>VetoableChangeListener</code> to be removed
*/
public void removeVetoableChangeListener(String name, VetoableChangeListener vcl) {
vcSupport.removeVetoableChangeListener(name, vcl);
}
/**
* A service provided by the nesting BeanContext has been revoked.
*
* Subclasses may override this method in order to implement their own
* behaviors.
* @param bcsre The <code>BeanContextServiceRevokedEvent</code> fired as a
* result of a service being revoked
*/
public void serviceRevoked(BeanContextServiceRevokedEvent bcsre) { }
/**
* A new service is available from the nesting BeanContext.
*
* Subclasses may override this method in order to implement their own
* behaviors
* @param bcsae The BeanContextServiceAvailableEvent fired as a
* result of a service becoming available
*
*/
public void serviceAvailable(BeanContextServiceAvailableEvent bcsae) { }
/**
* Gets the <tt>BeanContextChild</tt> associated with this
* <tt>BeanContextChildSupport</tt>.
*
* @return the <tt>BeanContextChild</tt> peer of this class
*/
public BeanContextChild getBeanContextChildPeer() { return beanContextChildPeer; }
/**
* Reports whether or not this class is a delegate of another.
*
* @return true if this class is a delegate of another
*/
public boolean isDelegated() { return !this.equals(beanContextChildPeer); }
/**
* Report a bound property update to any registered listeners. No event is
* fired if old and new are equal and non-null.
* @param name The programmatic name of the property that was changed
* @param oldValue The old value of the property
* @param newValue The new value of the property
*/
public void firePropertyChange(String name, Object oldValue, Object newValue) {
pcSupport.firePropertyChange(name, oldValue, newValue);
}
/**
* Report a vetoable property update to any registered listeners.
* If anyone vetos the change, then fire a new event
* reverting everyone to the old value and then rethrow
* the PropertyVetoException. <P>
*
* No event is fired if old and new are equal and non-null.
* <P>
* @param name The programmatic name of the property that is about to
* change
*
* @param oldValue The old value of the property
* @param newValue - The new value of the property
*
* @throws PropertyVetoException if the recipient wishes the property
* change to be rolled back.
*/
public void fireVetoableChange(String name, Object oldValue, Object newValue) throws PropertyVetoException {
vcSupport.fireVetoableChange(name, oldValue, newValue);
}
/**
* Called from setBeanContext to validate (or otherwise) the
* pending change in the nesting BeanContext property value.
* Returning false will cause setBeanContext to throw
* PropertyVetoException.
* @param newValue the new value that has been requested for
* the BeanContext property
* @return <code>true</code> if the change operation is to be vetoed
*/
public boolean validatePendingSetBeanContext(BeanContext newValue) {
return true;
}
/**
* This method may be overridden by subclasses to provide their own
* release behaviors. When invoked any resources held by this instance
* obtained from its current BeanContext property should be released
* since the object is no longer nested within that BeanContext.
*/
protected void releaseBeanContextResources() {
// do nothing
}
/**
* This method may be overridden by subclasses to provide their own
* initialization behaviors. When invoked any resources requried by the
* BeanContextChild should be obtained from the current BeanContext.
*/
protected void initializeBeanContextResources() {
// do nothing
}
/**
* Write the persistence state of the object.
*/
private void writeObject(ObjectOutputStream oos) throws IOException {
/*
* dont serialize if we are delegated and the delegator isnt also
* serializable.
*/
if (!equals(beanContextChildPeer) && !(beanContextChildPeer instanceof Serializable))
throw new IOException("BeanContextChildSupport beanContextChildPeer not Serializable");
else
oos.defaultWriteObject();
}
/**
* Restore a persistent object, must wait for subsequent setBeanContext()
* to fully restore any resources obtained from the new nesting
* BeanContext
*/
private void readObject(ObjectInputStream ois) throws IOException, ClassNotFoundException {
ois.defaultReadObject();
}
/*
* fields
*/
/**
* The <code>BeanContext</code> in which
* this <code>BeanContextChild</code> is nested.
*/
public BeanContextChild beanContextChildPeer;
/**
* The <tt>PropertyChangeSupport</tt> associated with this
* <tt>BeanContextChildSupport</tt>.
*/
protected PropertyChangeSupport pcSupport;
/**
* The <tt>VetoableChangeSupport</tt> associated with this
* <tt>BeanContextChildSupport</tt>.
*/
protected VetoableChangeSupport vcSupport;
protected transient BeanContext beanContext;
/**
* A flag indicating that there has been
* at least one <code>PropertyChangeVetoException</code>
* thrown for the attempted setBeanContext operation.
*/
protected transient boolean rejectedSetBCOnce;
}
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