org.apache.wicket.ajax.AjaxEventBehavior.java Source code

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Here is the source code for org.apache.wicket.ajax.AjaxEventBehavior.java

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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;
import org.danekja.java.util.function.serializable.SerializableConsumer;

/**
 * An ajax behavior that is attached to a certain client-side (usually javascript) event, such as
 * click, change, keydown, etc.
 * <p>
 * Example:
 * 
 * <pre>
 *         WebMarkupContainer div=new WebMarkupContainer(...);
 *         div.setOutputMarkupId(true);
 *         div.add(new AjaxEventBehavior(&quot;click&quot;) {
 *             protected void onEvent(AjaxRequestTarget target) {
 *                 System.out.println(&quot;ajax here!&quot;);
 *             }
 *         }
 * </pre>
 * 
 * This behavior will be linked to the <em>click</em> javascript event of the div WebMarkupContainer
 * represents, and so anytime a user clicks this div the {@link #onEvent(AjaxRequestTarget)} of the
 * behavior is invoked.
 *
 * <p>
 * <strong>Note</strong>: {@link #getEvent()} method cuts any <em>on</em> 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
 * <em>on</em> then {@link #getEvent()} should be overridden.
 * </p>
 *
 * @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");

        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);
    }

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

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

    @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);

    /**
     * Creates an {@link AjaxEventBehavior} based on lambda expressions
     * 
     * @param eventName
     *            the event name
     * @param onEvent
     *            the {@code SerializableConsumer} which accepts the {@link AjaxRequestTarget}
     * @return the {@link AjaxEventBehavior}
     */
    public static AjaxEventBehavior onEvent(String eventName, SerializableConsumer<AjaxRequestTarget> onEvent) {
        Args.notNull(onEvent, "onEvent");

        return new AjaxEventBehavior(eventName) {
            private static final long serialVersionUID = 1L;

            @Override
            protected void onEvent(AjaxRequestTarget target) {
                onEvent.accept(target);
            }
        };
    }
}