API Enhancements to the JavaBeans^TM Component API in v1.4

This document describes changes to the java.beans package that were introduced in version 1.4 of the Java 2 Platform, Standard Edition.
To support long-term persistence, the following classes were added:

Class Description
Statement An object that represents a method call, possibly with arguments, upon an object. For example: a.setFoo(b).
     Expression A statement that returns a result. For example: a.getFoo().
XMLDecoder Reads XML documents that were created using XMLEncoder.
Encoder Uses persistence delegates to break an object graph down into a series of Statements and Expressions that can be used to recreate it.
     XMLEncoder An Encoder that produces statements and expressions in an XML encoding.
PersistenceDelegate An abstract class that defines objects that can express the state of another object using the public methods of that object's class.
    DefaultPersistenceDelegate The persistence delegate used, by default, for beans.

See JavaBeans Component API for links to where you can find more information about long-term persistence.
The following classes were also added in v1.4:

Class Description
EventHandler Provides support for dynamically generating event listeners that have a small footprint and can be saved automatically by the persistence scheme.
ExceptionListener Defines a listener to be notified when a exception was thrown but then recovered from. You can register an exception listener on an XMLEncoder or XMLDecoder object to be notified when the object encounters a recoverable problem while writing or reading a bean.
PropertyChangeListenerProxy A proxy that implements PropertyChangeListener and serves to group another PropertyChangeListener (the real event handler) with a specific property; the proxy forwards property change events to the real event handler.
VetoableChangeListenerProxy A proxy that implements VetoableChangeListener and serves to group another VetoableChangeListener (the real event handler) with a specific constrained property; the proxy forwards vetoable property change events to the real event handler.

The following classes have additional methods:

The PropertyChangeSupport class now contains a no-argument method to get all the registered property change listeners: getPropertyChangeListeners.
Similarly, the VetoableChangeSupport class now contains a no-argument method to get all the registered vetoable change listeners: getVetoableChangeListeners.
The Introspector class has been reimplemented, and its performance has improved. The new implementation has caused the following changes in the behavior of the introspector:

FeatureDescriptors are now shared, rather than copied. This change cuts down on the space requirements of BeanInfos. It also means that when a value in a PropertyDescriptor changes, that change is perpetuated throughout the BeanInfo.

The getBeanInfo methods no longer create a copy of the requested BeanInfo. Instead, they cache the BeanInfo and return it. If necessary, you can get the old behavior by storing a reference to the returned BeanInfo and using the flushFromCaches method to flush the bean's class from the introspector's cache.

If the instantiate method can't instantiate a particular class using the sibling or bootstrap class loader, it now tries to load the class using the current thread's class loader.

Java Software

Class	Description
`Statement`	An object that represents a method call, possibly with arguments, upon an object. For example: `a.setFoo(b)`.
`Expression`	A statement that returns a result. For example: `a.getFoo()`.
`XMLDecoder`	Reads XML documents that were created using `XMLEncoder`.
`Encoder`	Uses persistence delegates to break an object graph down into a series of `Statement`s and `Expression`s that can be used to recreate it.
`XMLEncoder`	An `Encoder` that produces statements and expressions in an XML encoding.
`PersistenceDelegate`	An abstract class that defines objects that can express the state of another object using the public methods of that object's class.
`DefaultPersistenceDelegate`	The persistence delegate used, by default, for beans.

Class	Description
`EventHandler`	Provides support for dynamically generating event listeners that have a small footprint and can be saved automatically by the persistence scheme.
`ExceptionListener`	Defines a listener to be notified when a exception was thrown but then recovered from. You can register an exception listener on an `XMLEncoder` or `XMLDecoder` object to be notified when the object encounters a recoverable problem while writing or reading a bean.
`PropertyChangeListenerProxy`	A proxy that implements `PropertyChangeListener` and serves to group another `PropertyChangeListener` (the real event handler) with a specific property; the proxy forwards property change events to the real event handler.
`VetoableChangeListenerProxy`	A proxy that implements `VetoableChangeListener` and serves to group another `VetoableChangeListener` (the real event handler) with a specific constrained property; the proxy forwards vetoable property change events to the real event handler.

API Enhancements to the JavaBeansTM Component API in v1.4

API Enhancements to the JavaBeans^TM Component API in v1.4