org.obiba.onyx.wicket.behavior.AbstractAjaxTimerBehavior.java Source code

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Here is the source code for org.obiba.onyx.wicket.behavior.AbstractAjaxTimerBehavior.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.obiba.onyx.wicket.behavior;

import org.apache.wicket.Page;
import org.apache.wicket.RequestCycle;
import org.apache.wicket.ajax.AbstractDefaultAjaxBehavior;
import org.apache.wicket.ajax.AjaxRequestTarget;
import org.apache.wicket.ajax.IAjaxCallDecorator;
import org.apache.wicket.ajax.calldecorator.AjaxCallDecorator;
import org.apache.wicket.markup.html.IHeaderResponse;
import org.apache.wicket.protocol.http.WebRequest;
import org.apache.wicket.util.time.Duration;

/**
 * A behavior that generates an AJAX update callback at a regular interval.
 * 
 * @since 1.2
 * 
 * @author Igor Vaynberg (ivaynberg)
 * 
 */
public abstract class AbstractAjaxTimerBehavior extends AbstractDefaultAjaxBehavior {
    /**
     * 
     */
    private static final long serialVersionUID = 1L;

    /** The update interval */
    private Duration updateInterval;

    private boolean stopped = false;

    private boolean headRendered = false;

    /**
     * Construct.
     * 
     * @param updateInterval Duration between AJAX callbacks
     */
    public AbstractAjaxTimerBehavior(final Duration updateInterval) {
        if (updateInterval == null || updateInterval.getMilliseconds() <= 0) {
            throw new IllegalArgumentException("Invalid update interval");
        }
        this.updateInterval = updateInterval;
    }

    @Override
    protected IAjaxCallDecorator getAjaxCallDecorator() {
        return new AjaxCallDecorator() {
            /**
             * 
             */
            private static final long serialVersionUID = 1L;

            @Override
            public CharSequence decorateScript(CharSequence script) {
                return "var timeout;";
            }
        };
    }

    /**
     * Stops the timer
     */
    public final void stop() {
        stopped = true;
    }

    public final void start(final AjaxRequestTarget target) {
        stopped = false;
        target.getHeaderResponse().renderOnLoadJavascript(getJsTimeoutCall(updateInterval));
    }

    /**
     * Sets the update interval duration. This method should only be called within the {@link #onTimer(AjaxRequestTarget)}
     * method.
     * 
     * @param updateInterval
     */
    protected final void setUpdateInterval(Duration updateInterval) {
        if (updateInterval == null || updateInterval.getMilliseconds() <= 0) {
            throw new IllegalArgumentException("Invalid update interval");
        }
        this.updateInterval = updateInterval;
    }

    /**
     * Returns the update interval
     * 
     * @return The update interval
     */
    public final Duration getUpdateInterval() {
        return updateInterval;
    }

    /**
     * @see org.apache.wicket.behavior.AbstractAjaxBehavior#renderHead(org.apache.wicket.markup.html.IHeaderResponse)
     */
    public void renderHead(IHeaderResponse response) {
        super.renderHead(response);

        WebRequest request = (WebRequest) RequestCycle.get().getRequest();

        if (!stopped && (!headRendered || !request.isAjax())) {
            headRendered = true;
            response.renderOnLoadJavascript(getJsTimeoutCall(updateInterval));
        }
    }

    /**
     * @param updateInterval Duration between AJAX callbacks
     * @return JS script
     */
    protected final String getJsTimeoutCall(final Duration updateInterval) {
        // this might look strange, but it is necessary for IE not to leak :(
        return "timeout = setTimeout(\"" + getCallbackScript() + "\", " + updateInterval.getMilliseconds() + ");";
    }

    protected CharSequence getCallbackScript() {
        return generateCallbackScript("wicketAjaxGet('" + getCallbackUrl(onlyTargetActivePage()) + "'");
    }

    /**
     * @see org.apache.wicket.ajax.AbstractDefaultAjaxBehavior#getPreconditionScript()
     */
    protected CharSequence getPreconditionScript() {
        String precondition = null;
        if (!(getComponent() instanceof Page)) {
            String componentId = getComponent().getMarkupId();
            precondition = "var c = Wicket.$('" + componentId + "'); return typeof(c) != 'undefined' && c != null";
        }
        return precondition;
    }

    protected boolean onlyTargetActivePage() {
        return true;
    }

    /**
     * 
     * @see org.apache.wicket.ajax.AbstractDefaultAjaxBehavior#respond(org.apache.wicket.ajax.AjaxRequestTarget)
     */
    protected final void respond(final AjaxRequestTarget target) {
        onTimer(target);
        if (!stopped) {
            target.getHeaderResponse().renderOnLoadJavascript(getJsTimeoutCall(updateInterval));
        }
    }

    /**
     * Listener method for the AJAX timer event.
     * 
     * @param target The request target
     */
    protected abstract void onTimer(final AjaxRequestTarget target);
}