Description Tim Hollosy 2008-04-08 16:52:17 EDT

A common requirement to use model objects (Entities) with the Databinding Frameworks such as JFace Databinding is is to have the Model Object provide bound property support through the PropertyChangeSupport class.

See:
http://java.sun.com/j2se/1.5.0/docs/api/java/beans/PropertyChangeSupport.html

This entails having your setters in a pattern like:

public void setName(String name) {
  if (this.name == null && name == null) {
    return;
  }
  firePropertyChange("name", this.name, this.name = name);
}

And having your Model (Entity in this case) extend a base class that implements the methods:

		private PropertyChangeSupport propertyChangeSupport = new PropertyChangeSupport(
				this);

		public void addPropertyChangeListener(PropertyChangeListener listener) {
			propertyChangeSupport.addPropertyChangeListener(listener);
		}

		public void addPropertyChangeListener(String propertyName,
				PropertyChangeListener listener) {
			propertyChangeSupport.addPropertyChangeListener(propertyName,
					listener);
		}

		public void removePropertyChangeListener(PropertyChangeListener listener) {
			propertyChangeSupport.removePropertyChangeListener(listener);
		}

		public void removePropertyChangeListener(String propertyName,
				PropertyChangeListener listener) {
			propertyChangeSupport.removePropertyChangeListener(propertyName,
					listener);
		}

		protected void firePropertyChange(String propertyName, Object oldValue,
				Object newValue) {
			propertyChangeSupport.firePropertyChange(propertyName, oldValue,
					newValue);
		}


Other similar plugins like HiberObjects currently offer PropertyChangeSupport implementations in their Entity generation, it would be nice if JPA Tools did the same.