jakarta.faces.view.facelets.ComponentHandler Maven / Gradle / Ivy
/*
* Copyright (c) 1997, 2020 Oracle and/or its affiliates. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v. 2.0, which is available at
* http://www.eclipse.org/legal/epl-2.0.
*
* This Source Code may also be made available under the following Secondary
* Licenses when the conditions for such availability set forth in the
* Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
* version 2 with the GNU Classpath Exception, which is available at
* https://www.gnu.org/software/classpath/license.html.
*
* SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
*/
package jakarta.faces.view.facelets;
import jakarta.faces.component.UIComponent;
/**
*
* Public base class for markup element instances that map to
* {@link UIComponent} instances in the view.
*
*
*
*
*
* Instances of this class are created and passed to
* {@link TagHandlerDelegateFactory#createComponentHandlerDelegate} 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.
*
*
*
*
* -
*
* The UIComponent represented by this element is created with the appropriate
* Application.createComponent() method.
*
*
*
* -
*
* Each attribute specified in the markup is correctly applied to the component instance, as specified in the VDLDocs
* for this element.
*
*
*
* -
*
* If project stage is {@link jakarta.faces.application.ProjectStage#Development}, Put the
* {@link jakarta.faces.view.Location} for this element into the component attribute Map under the key
* given by the value of the symbolic constant {@link jakarta.faces.component.UIComponent#VIEW_LOCATION_KEY}.
*
*
*
* -
*
* 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 {@link jakarta.faces.component.UniqueIdVendor} must
* be located and its {@link jakarta.faces.component.UniqueIdVendor#createUniqueId} method must be called to derive the
* id. If no such instance can be found, call {@link jakarta.faces.component.UIViewRoot#createUniqueId} to derive the
* id.
*
*
*
* -
*
* The rendererType property of the component is set properly.
*
*
*
* -
*
* {@link #onComponentCreated} is called.
*
*
*
* -
*
* {@link UIComponent#pushComponentToEL} is called on the newly created component.
*
*
*
* -
*
* The next handler in the facelet chain is applied. This will cause the component to be populated with children.
*
*
*
* -
*
* The component is added to its parent in the view.
*
*
*
* -
*
* {@link UIComponent#popComponentFromEL} is called on the newly created component.
*
*
*
* -
*
* Call {@link 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.
*
*
*
*
* -
*
* To control the instantiation of the UIComponent instance, subclasses may override
* {@link #createComponent}. If this method is not overridden, the tag handler for which this instance is the delegate
* will take the necessary action to instantiate the UIComponent.
*
*
*
* -
*
* To be notified of creation of the UIComponentinstance, subclasses may override
* {@link #onComponentCreated}.
*
*
*
* -
*
* To be notified that the freshly created UIComponent instance has been populated with children as a
* result of execution of child tag handlers, subclasses may override {@link #onComponentPopulated}.
*
*
*
*
*
*
*
* @since 2.0
*/
public class ComponentHandler extends DelegatingMetaTagHandler {
private TagHandlerDelegate helper = null;
private ComponentConfig componentConfig = null;
/**
*
* Leverage the {@link TagHandlerDelegateFactory} provided by the implementation to create an instance of
* {@link TagHandlerDelegate} designed for use with ComponentHandler.
*
*
* @param config the configuration for this handler.
*
* @since 2.0
*/
public ComponentHandler(ComponentConfig config) {
super(config);
componentConfig = config;
}
@Override
protected TagHandlerDelegate getTagHandlerDelegate() {
if (null == helper) {
helper = delegateFactory.createComponentHandlerDelegate(this);
}
return helper;
}
public ComponentConfig getComponentConfig() {
return componentConfig;
}
/**
*
* 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.
*
*
* @param ctx the FaceletContext for this view execution
*
* @return the newly created {@link UIComponent}
*
* @since 2.2
*/
public UIComponent createComponent(FaceletContext ctx) {
return null;
}
/**
*
* This method is guaranteed to be called after the component has been created but before it has been populated with
* children.
*
*
* @param ctx the FaceletContext for this view execution
*
* @param c the UIComponent that has just been created.
*
* @param parent the parent UIComponent of the component represented by this element instance.
*
* @since 2.0
*/
public void onComponentCreated(FaceletContext ctx, UIComponent c, UIComponent parent) {
}
/**
*
* This method is guaranteed to be called after the component has been populated with children.
*
*
* @param ctx the FaceletContext for this view execution
*
* @param c the UIComponent that has just been populated with children.
*
* @param parent the parent UIComponent of the component represented by this element instance.
*
* @since 2.0
*/
public void onComponentPopulated(FaceletContext ctx, UIComponent c, UIComponent parent) {
}
/**
*
* 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.
*
*
* @param component the component you wish to modify
*
* @return true if and only if the argument is not {@code null} and the component is new during this run of the
* lifecycle.
*
* @since 2.0
*/
public static boolean isNew(UIComponent component) {
UIComponent c = component;
if (c != null) {
UIComponent parent = c.getParent();
if (parent != null) {
if (UIComponent.isCompositeComponent(parent)) {
c = parent;
}
}
return c.getParent() == null;
} else {
return false;
}
}
}