Registering a Custom Component - The J2EE 1.4 Tutorial

Registering a Custom Component

In addition to registering custom renderers (as explained in the preceding section), you also must register the custom components that are usually associated with the custom renderers.

Here is the component element from the application configuration resource file that registers AreaComponent:
<component>
  <component-type>DemoArea</component-type>
  <component-class>
    components.AreaComponent
  </component-class>
  <property>
    <property-name>alt</property-name>
    <property-class>java.lang.String</property-class>
  </property>
  <property>
    <property-name>coords</property-name>
    <property-class>java.lang.String</property-class>
  </property>
  <property>
    <property-name>shape</property-name>
    <property-class>java.lang.String</property-class>
  </property>

  <component-extension>
    <component-family>Area</component-family>
    <renderer-type>DemoArea</renderer-type>
  </component-extension>

</component> 
The component-type element indicates the name under which the component should be registered. Other objects referring to this component use this name. For example, the component-type element in the configuration for AreaComponent defines a value of DemoArea, which matches the value returned by the AreaTag class's getComponentType method.

The component-class element indicates the fully qualified class name of the component. The property elements specify the component properties and their types.

If the custom component can include facets, you can configure the facets in the component configuration using facet elements, which are allowed after the component-class elements. See Registering a Custom Renderer with a Render Kit for further details on configuring facets.

The component-extension element identifies a component family and a renderer type. The component family represents a component or set of components that a renderer can render. The renderer type specifies the renderer that can render the components included in the component family.

The component family specified by the component-family element must match that returned by the components' getFamily methods. The renderer-type must match that returned by the tag handler's getRendererType method. By using the component family and renderer type to look up renderers for components, the JavaServer Faces implementation allows a component to be rendered by multiple renderers and allows a renderer to render multiple components.