abstractajaxbehavior.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.RequestListenerInterface;
import org.apache.wicket.Response;
import org.apache.wicket.markup.ComponentTag;
import org.apache.wicket.markup.html.IHeaderContributor;
import org.apache.wicket.markup.html.IHeaderResponse;

/**
 * Abstract class for handling Ajax roundtrips. This class serves as a base for javascript specific
 * implementations, like ones based on Dojo or Scriptaculous, or Wicket's default.
 * 
 * @author Eelco Hillenius
 * @author Ralf Ebert
 * @author Igor Vaynberg
 */
public abstract class AbstractAjaxBehavior extends AbstractBehavior
		implements
			IBehaviorListener,
			IHeaderContributor
{
	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;
	/** the component that this handler is bound to. */
	private Component component;

	/**
	 * Construct.
	 */
	public AbstractAjaxBehavior()
	{
	}

	/**
	 * Bind this handler to the given component.
	 * 
	 * @param hostComponent
	 *            the component to bind to
	 */
	public final void bind(final Component hostComponent)
	{
		if (hostComponent == null)
		{
			throw new IllegalArgumentException("Argument hostComponent must be not null");
		}

		if (component != null)
		{
			throw new IllegalStateException("this kind of handler cannot be attached to " +
					"multiple components; it is already attached to component " + component +
					", but component " + hostComponent + " wants to be attached too");

		}

		component = hostComponent;

		// call the callback
		onBind();
	}

	/**
	 * Gets the url that references this handler.
	 * 
	 * @return the url that references this handler
	 */
	public CharSequence getCallbackUrl()
	{
		return getCallbackUrl(true);
	}

	/**
	 * Gets the url that references this handler.
	 * 
	 * @param onlyTargetActivePage
	 *            if true the callback to this behavior will be ignore if the page is not the last
	 *            one the user accessed
	 * 
	 * @return the url that references this handler
	 */
	public final CharSequence getCallbackUrl(final boolean onlyTargetActivePage)
	{
		if (getComponent() == null)
		{
			throw new IllegalArgumentException(
					"Behavior must be bound to a component to create the URL");
		}

		final RequestListenerInterface rli;

		if (onlyTargetActivePage)
		{
			rli = IActivePageBehaviorListener.INTERFACE;
		}
		else
		{
			rli = IBehaviorListener.INTERFACE;
		}

		return getComponent().urlFor(this, rli);
	}

	/**
	 * @see org.apache.wicket.behavior.IBehavior#onComponentTag(org.apache.wicket.Component,
	 *      org.apache.wicket.markup.ComponentTag)
	 */
	public final void onComponentTag(final Component component, final ComponentTag tag)
	{
		onComponentTag(tag);
	}

	/**
	 * @see org.apache.wicket.behavior.AbstractBehavior#onRendered(org.apache.wicket.Component)
	 */
	public final void onRendered(final Component hostComponent)
	{
		onComponentRendered();
	}

	/**
	 * @see org.apache.wicket.markup.html.IHeaderContributor#renderHead(IHeaderResponse)
	 */
	public void renderHead(final IHeaderResponse response)
	{
	}

	/**
	 * Gets the component that this handler is bound to.
	 * 
	 * @return the component that this handler is bound to
	 */
	protected final Component getComponent()
	{
		return component;
	}

	/**
	 * Called any time a component that has this handler registered is rendering the component tag.
	 * Use this method e.g. to bind to javascript event handlers of the tag
	 * 
	 * @param tag
	 *            the tag that is rendered
	 */
	protected void onComponentTag(final ComponentTag tag)
	{
	}

	/**
	 * Called when the component was bound to it's host component. You can get the bound host
	 * component by calling getComponent.
	 */
	protected void onBind()
	{
	}

	/**
	 * Called to indicate that the component that has this handler registered has been rendered. Use
	 * this method to do any cleaning up of temporary state
	 */
	protected void onComponentRendered()
	{
	}

	/**
	 * @see org.apache.wicket.behavior.AbstractBehavior#getStatelessHint(Component)
	 */
	public boolean getStatelessHint(Component component)
	{
		return false;
	}


	// TODO the next three methods will be removed with next commit. Here as
	// final to help with refactoring

	protected final String getImplementationId()
	{
		return "foo";
	}

	protected final void onRenderHeadContribution(final Response response)
	{
	}

	protected final void onRenderHeadInitContribution(final Response response)
	{
	}
}