Package jakarta.faces.view.facelets

Class ComponentHandler

java.lang.Object
jakarta.faces.view.facelets.TagHandler
jakarta.faces.view.facelets.MetaTagHandler
jakarta.faces.view.facelets.DelegatingMetaTagHandler
jakarta.faces.view.facelets.ComponentHandler
All Implemented Interfaces:
FaceletHandler
public class ComponentHandler extends DelegatingMetaTagHandler

Public base class for markup element instances that map to UIComponent instances in the view.

Instances of this class are created and passed to TagHandlerDelegateFactory.createComponentHandlerDelegate(jakarta.faces.view.facelets.ComponentHandler) when a tag corresponding to this particular component is encountered in a Facelet view. A custom tag handler for a component, converter, validator, or behavior must extend from this class. In this way, this instance acts as a delegate for the implementation private tag handler. Such a subclass may choose to override as many or as few methods from this base class as desired. If the subclass wants to completely override the action of the implementation specific tag for which this component is the delegate, it must override the apply() method and make it take the following actions, in this order. These actions must only happen the first time this facelet is applied for each user. Subsequent applications must take no action.

  1. The UIComponent represented by this element is created with the appropriate Application.createComponent() method.

  2. Each attribute specified in the markup is correctly applied to the component instance, as specified in the VDLDocs for this element.

  3. If project stage is ProjectStage.Development, Put the Location for this element into the component attribute Map under the key given by the value of the symbolic constant UIComponent.VIEW_LOCATION_KEY.

  4. Set the id of the component. If the id is specified manually by the page author, that value must be set as the id. Otherwise, the closest ancestor component that is an instance of UniqueIdVendor must be located and its UniqueIdVendor.createUniqueId(jakarta.faces.context.FacesContext, java.lang.String) method must be called to derive the id. If no such instance can be found, call UIViewRoot.createUniqueId() to derive the id.

  5. The rendererType property of the component is set properly.

  6. onComponentCreated(jakarta.faces.view.facelets.FaceletContext, jakarta.faces.component.UIComponent, jakarta.faces.component.UIComponent) is called.

  7. UIComponent.pushComponentToEL(jakarta.faces.context.FacesContext, jakarta.faces.component.UIComponent) is called on the newly created component.

  8. The next handler in the facelet chain is applied. This will cause the component to be populated with children.

  9. The component is added to its parent in the view.

  10. UIComponent.popComponentFromEL(jakarta.faces.context.FacesContext) is called on the newly created component.

  11. Call UIComponent.markInitialState().

A common use case for extending this class is to gain access to the process by which the Facelets runtime creates component instances corresponding to markup in a Facelets view. These three methods are useful in such cases.

Since:
2.0

  • Constructor Details

    • ComponentHandler

      public ComponentHandler(ComponentConfig config)

      Leverage the TagHandlerDelegateFactory provided by the implementation to create an instance of TagHandlerDelegate designed for use with ComponentHandler.

      Parameters:
      config - the configuration for this handler.
      Since:
      2.0

  • Method Details

    • getTagHandlerDelegate

      protected TagHandlerDelegate getTagHandlerDelegate()
      Description copied from class: DelegatingMetaTagHandler

      Get the tag handler delegate.

      Code that extends from DelegatingMetaTagHandler (directly or indirectly, as through extending ComponentHandler) must take care to decorate, not replace, the TagHandlerDelegate instance returned by this method. Failure to do so may produce unexpected results.

      Specified by:
      getTagHandlerDelegate in class DelegatingMetaTagHandler
      Returns:
      the tag handler delegate.

    • getComponentConfig

      public ComponentConfig getComponentConfig()
      Returns the component configuration, a component-type/renderer-type pair.
      Returns:
      the component configuration

    • createComponent

      public UIComponent createComponent(FaceletContext ctx)

      Subclasses that wish to take over the task of instantiating the UIComponent instance corresponding to this tag handler my override this method to do so. A null return from this method will cause the TagHandlerDelegate for instance to create the component instead.

      Parameters:
      ctx - the FaceletContext for this view execution
      Returns:
      the newly created UIComponent
      Since:
      2.2

    • onComponentCreated

      public void onComponentCreated(FaceletContext ctx, UIComponent c, UIComponent parent)

      This method is guaranteed to be called after the component has been created but before it has been populated with children.

      Parameters:
      ctx - the FaceletContext for this view execution
      c - the UIComponent that has just been created.
      parent - the parent UIComponent of the component represented by this element instance.
      Since:
      2.0

    • onComponentPopulated

      public void onComponentPopulated(FaceletContext ctx, UIComponent c, UIComponent parent)

      This method is guaranteed to be called after the component has been populated with children.

      Parameters:
      ctx - the FaceletContext for this view execution
      c - the UIComponent that has just been populated with children.
      parent - the parent UIComponent of the component represented by this element instance.
      Since:
      2.0

    • isNew

      public static boolean isNew(UIComponent component)

      Determine if the passed component is not null and if it's new to the tree. This operation can be used for determining if attributes should be wired to the component.

      Parameters:
      component - the component you wish to modify
      Returns:
      true if and only if the argument is not null and the component is new during this run of the lifecycle.
      Since:
      2.0