org.antbear.jee.wicket.GeolocationAjaxBehavior.java Source code

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Here is the source code for org.antbear.jee.wicket.GeolocationAjaxBehavior.java

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/*
 * Copyright 2011 Marcus Geiger.
 *
 * Licensed 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.antbear.jee.wicket;

import org.apache.wicket.Component;
import org.apache.wicket.ajax.AbstractDefaultAjaxBehavior;
import org.apache.wicket.ajax.AjaxRequestTarget;
import org.apache.wicket.markup.html.IHeaderResponse;
import org.apache.wicket.request.IRequestParameters;
import org.apache.wicket.request.Request;
import org.apache.wicket.request.cycle.RequestCycle;
import org.apache.wicket.request.resource.PackageResourceReference;
import org.apache.wicket.util.string.StringValue;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Provides geographic location information via HTML5 Geolocation services.
 *
 * @author Marcus Geiger
 */
public abstract class GeolocationAjaxBehavior extends AbstractDefaultAjaxBehavior {
    private static final long serialVersionUID = 1L;

    private static Logger log = LoggerFactory.getLogger(GeolocationAjaxBehavior.class);

    protected abstract void onLocation(AjaxRequestTarget target, double latitude, double longitude);

    protected abstract void onError(AjaxRequestTarget target, String message); // TODO provide enum for kind of error

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

        // Create javascript function that calls wicket to provide geolocation information
        CharSequence url = getCallbackUrl();
        response.renderJavaScript("function geolocationCallWicket(status, message, position) {" + "var args = '';"
                + "if (status) {" + "var lat = position.coords.latitude;" + "var lon = position.coords.longitude;"
                + "args = '&status=1&lat='+lat+'&lon='+lon;" + "} else {" + "args = '&status=0&msg=' + message;"
                + "}" + "var wcall = wicketAjaxGet('" + url + "' + args, function() {}, function() {});" + "}",
                null);

        // Include the geolocation javascript file
        response.renderJavaScriptReference(new PackageResourceReference(GeolocationAjaxBehavior.class,
                GeolocationAjaxBehavior.class.getSimpleName() + ".js"));

        // Initialize geolocation
        response.renderOnDomReadyJavaScript("initGeolocationAjaxBehavior()");
    }

    @Override
    protected void respond(AjaxRequestTarget target) {
        log.debug("respond");

        Request request = RequestCycle.get().getRequest();
        IRequestParameters requestParameters = request.getRequestParameters();

        StringValue svStatus = requestParameters.getParameterValue("status");
        if (svStatus == null || svStatus.isNull() || svStatus.isEmpty())
            throw new RuntimeException("Invariant violation: status is a required parameter");
        Integer status = svStatus.toInteger();

        if (status == 0) {
            StringValue svMessage = requestParameters.getParameterValue("msg");
            if (svMessage == null || svMessage.isNull() || svMessage.isEmpty())
                throw new RuntimeException("Invariant violation: message is a required parameter");

            log.debug("Geolocation failed: " + svMessage.toString());
            onError(target, svMessage.toString());

        } else {
            StringValue svLatitude = requestParameters.getParameterValue("lat");
            if (svLatitude == null || svLatitude.isNull() || svLatitude.isEmpty())
                throw new RuntimeException("Invariant violation: message is a required parameter");

            StringValue svLongitude = requestParameters.getParameterValue("lon");
            if (svLongitude == null || svLongitude.isNull() || svLongitude.isEmpty())
                throw new RuntimeException("Invariant violation: message is a required parameter");

            log.debug("Geolocation received: lat " + svLatitude.toDouble() + ", lon " + svLongitude.toDouble());
            onLocation(target, svLatitude.toDouble(), svLongitude.toDouble());
        }
    }
}