The Java EE 5 Tutorial (PDF) - Oracle Software Downloads

The value attributes of the area tags refer to the beans in the application scope, as shown in this
area tag from chooselocale.jsp:
To reference the ImageArea model object bean values from the component class, you
implement a getValue method in the component class. This method calls super.getValue.
The superclass of
tut-install/javaeetutorial5/examples/web/bookstore6/src/java/com/sun/bookstore6/componen
UIOutput, has a getValue method that does the work of finding the ImageArea object
associated with AreaComponent. The AreaRenderer class, which needs to render the alt, shape,
and coords values from the ImageArea object, calls the getValue method of AreaComponent to
retrieve the ImageArea object.
ImageArea iarea = (ImageArea) area.getValue();
ImageArea is only a simple bean, so you can access the shape, coordinates, and alternative text
values by calling the appropriate accessor methods of ImageArea. “Creating the Renderer Class”
on page 425 explains how to do this in the AreaRenderer class.
Summary of the Application Classes
Table 13–2 summarizes all the classes needed to implement the image map component.
TABLE 13–2 Image Map Classes
Class Function
AreaSelectedEvent The ActionEvent indicating that an AreaComponent from the MapComponent has been
selected.
AreaTag The tag handler that implements the area custom tag.
MapTag The tag handler that implements the map custom tag.
AreaComponent The class that defines AreaComponent, which corresponds to the area custom tag.
MapComponent The class that defines MapComponent, which corresponds to the map custom tag.
AreaRenderer This Renderer performs the delegated rendering for AreaComponent.
ImageArea The bean that stores the shape and coordinates of the hotspots.
LocaleBean The backing bean for the chooselocale.jsp page.
Understanding the Image Map Example
Chapter 13 • Creating Custom UI Components 415