org.apache.wicket.ajax.AjaxEventBehavior Maven / Gradle / Ivy

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Wicket is a Java web application framework that takes simplicity, separation of concerns and ease of development to a whole new level. Wicket pages can be mocked up, previewed and later revised using standard WYSIWYG HTML design tools. Dynamic content processing and form handling is all handled in Java code using a first-class component model backed by POJO data beans that can easily be persisted using your favorite technology.

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/*
 * 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.ajax;

import java.util.ArrayList;
import java.util.List;

import org.apache.wicket.Component;
import org.apache.wicket.ajax.attributes.AjaxRequestAttributes;
import org.apache.wicket.markup.head.IHeaderResponse;
import org.apache.wicket.markup.head.OnDomReadyHeaderItem;
import org.apache.wicket.util.lang.Args;
import org.apache.wicket.util.lang.Checks;
import org.apache.wicket.util.string.Strings;

/**
 * An ajax behavior that is attached to a certain client-side (usually javascript) event, such as
 * click, change, keydown, etc.
 * 
 * Example:
 * 
 * 
 *         WebMarkupContainer div=new WebMarkupContainer(...);
 *         div.setOutputMarkupId(true);
 *         div.add(new AjaxEventBehavior("click") {
 *             protected void onEvent(AjaxRequestTarget target) {
 *                 System.out.println("ajax here!");
 *             }
 *         }
 * 
 * 
 * This behavior will be linked to the click javascript event of the div WebMarkupContainer
 * represents, and so anytime a user clicks this div the {@link #onEvent(AjaxRequestTarget)} of the
 * behavior is invoked.
 *
 * 
 * Note: {@link #getEvent()} method cuts any on prefix from the given event name(s).
 * This is being done for easier migration of applications coming from Wicket 1.5.x where Wicket used
 * inline attributes like 'onclick=...'. If the application needs to use custom events with names starting with
 * on then {@link #getEvent()} should be overridden.
 * 
 *
 * @since 1.2
 * 
 * @author Igor Vaynberg (ivaynberg)
 * @see #onEvent(AjaxRequestTarget)
 */
public abstract class AjaxEventBehavior extends AbstractDefaultAjaxBehavior
{
	private static final long serialVersionUID = 1L;

	private final String event;

	/**
	 * Construct.
	 * 
	 * @param event
	 *      the event this behavior will be attached to
	 */
	public AjaxEventBehavior(String event)
	{
		Args.notEmpty(event, "event");

		onCheckEvent(event);

		this.event = event;
	}

	@Override
	public void renderHead(final Component component, final IHeaderResponse response)
	{
		super.renderHead(component, response);

		if (component.isEnabledInHierarchy())
		{
			CharSequence js = getCallbackScript(component);

			response.render(OnDomReadyHeaderItem.forScript(js.toString()));
		}
	}

	@Override
	protected void updateAjaxAttributes(AjaxRequestAttributes attributes)
	{
		super.updateAjaxAttributes(attributes);

		String evt = getEvent();
		Checks.notEmpty(evt, "getEvent() should return non-empty event name(s)");
		attributes.setEventNames(evt);
	}

	/**
	 * 
	 * @param event
	 *      the event this behavior will be attached to
	 */
	protected void onCheckEvent(final String event)
	{
	}

	/**
	 * @return event
	 *      the event this behavior is attached to
	 */
	public String getEvent()
	{
		String[] splitEvents = event.split("\\s+");
		List cleanedEvents = new ArrayList(splitEvents.length);
		for (String evt : splitEvents)
		{
			if (Strings.isEmpty(evt) == false)
			{
				if (evt.startsWith("on"))
				{
					evt = evt.substring(2);
				}
				cleanedEvents.add(evt);
			}
		}

		return Strings.join(" ", cleanedEvents);
	}

	/**
	 * 
	 * @see org.apache.wicket.ajax.AbstractDefaultAjaxBehavior#respond(AjaxRequestTarget)
	 */
	@Override
	protected final void respond(final AjaxRequestTarget target)
	{
		onEvent(target);
	}

	/**
	 * Listener method for the ajax event
	 * 
	 * @param target
	 *      the current request handler
	 */
	protected abstract void onEvent(final AjaxRequestTarget target);
}