ibehavior.java

Wicket一个开发Java Web应用程序框架。它使得开发web应用程序变得容易而轻松。 Wicket利用一个POJO data beans组件使得它可以与任何持久层技术相结合。

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.wicket.behavior;

import org.apache.wicket.Component;
import org.apache.wicket.IClusterable;
import org.apache.wicket.markup.ComponentTag;

/**
 * Behaviors are kind of plug-ins for Components. They allow to be added to a component and get
 * essential events forwarded by the component. they can be bound to a concrete component (using the
 * bind method is called when the behavior is attached), but they don't need to. They can modify the
 * components markup by changing the rendered ComponentTag. Behaviors can have their own models as
 * well, and they are notified when these are to be detached by the component.
 * <p>
 * It is recommended that you extend from {@link org.apache.wicket.behavior.AbstractBehavior}
 * instead of directly implementing this interface.
 * </p>
 * 
 * @see org.apache.wicket.behavior.IBehaviorListener
 * @see org.apache.wicket.markup.html.IHeaderContributor
 * @see org.apache.wicket.behavior.AbstractAjaxBehavior
 * @see org.apache.wicket.AttributeModifier
 * 
 * @author Ralf Ebert
 * @author Eelco Hillenius
 * @author Igor Vaynberg (ivaynberg)
 */
public interface IBehavior extends IClusterable
{
	/**
	 * Called when a component is about to render.
	 * 
	 * @param component
	 *            the component that has this behavior coupled
	 */
	void beforeRender(Component component);

	/**
	 * Called when a component that has this behavior coupled was rendered.
	 * 
	 * @param component
	 *            the component that has this behavior coupled
	 */
	void afterRender(Component component);

	/**
	 * Bind this handler to the given component. This method is called by the host component
	 * immediately after this behavior is added to it. This method is useful if you need to do
	 * initialization based on the component it is attached and you can't wait to do it at render
	 * time. Keep in mind that if you decide to keep a reference to the host component, it is not
	 * thread safe anymore, and should thus only be used in situations where you do not reuse the
	 * behavior for multiple components.
	 * 
	 * @param component
	 *            the component to bind to
	 */
	void bind(Component component);

	/**
	 * Allows the behavior to detach any state it has attached during request processing.
	 * 
	 * @param component
	 *            the component that initiates the detachment of this behavior
	 */
	void detach(Component component);

	/**
	 * In case an unexpected exception happened anywhere between onComponentTag() and rendered(),
	 * onException() will be called for any behavior. Typically, if you clean up resources in
	 * {@link #afterRender(Component)}, you should do the same in the implementation of this
	 * method.
	 * 
	 * @param component
	 *            the component that has a reference to this behavior and during which processing
	 *            the exception occurred
	 * @param exception
	 *            the unexpected exception
	 */
	void exception(Component component, RuntimeException exception);

	/**
	 * This method returns false if the behavior generates a callback url (for example ajax
	 * behaviors)
	 * 
	 * @param component
	 *            the component that has this behavior coupled.
	 * 
	 * @return boolean true or false.
	 */
	boolean getStatelessHint(Component component);

	/**
	 * Called when a components is rendering and wants to render this behavior. If false is returned
	 * this behavior will be ignored.
	 * 
	 * @param component
	 *            the component that has this behavior coupled
	 * 
	 * @return true if this behavior must be executed/rendered
	 */
	boolean isEnabled(Component component);

	/**
	 * Called any time a component that has this behavior registered is rendering the component tag.
	 * 
	 * @param component
	 *            the component that renders this tag currently
	 * @param tag
	 *            the tag that is rendered
	 */
	void onComponentTag(Component component, ComponentTag tag);

	/**
	 * Specifies whether or not this behavior is temporary. Temporary behaviors are removed at the
	 * end of request. Such behaviors are useful for modifying component rendering only when it
	 * renders next. Usecases include javascript effects, initial clientside dom setup, etc.
	 * 
	 * @return true if this behavior is temporary
	 */
	boolean isTemporary();
}