mx.org.pescadormvp.examples.jsonp.client.query.GetLatLonActionHelperImpl.java Source code

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Here is the source code for mx.org.pescadormvp.examples.jsonp.client.query.GetLatLonActionHelperImpl.java

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/*******************************************************************************
 * Copyright 2013 Instituto de Investigaciones Dr. Jos Mara Luis Mora
 * See LICENSE.txt for redistribution conditions.
 * 
 * D.R. 2013 Instituto de Investigaciones Dr. Jos Mara Luis Mora
 * Vase LICENSE.txt para los trminos bajo los cuales se permite
 * la redistribucin.
 ******************************************************************************/
package mx.org.pescadormvp.examples.jsonp.client.query;

import net.customware.gwt.dispatch.shared.Result;

import com.google.gwt.core.client.JavaScriptObject;
import com.google.gwt.safehtml.shared.UriUtils;

/**
 * Helps perform {@link GetLatLonAction}s.
 */
public class GetLatLonActionHelperImpl implements GetLatLonActionHelper {

    // This class is meant to be used only with this site, and with a specific
    // version of the API, so it's OK to hardcode these here.
    final static String BASE_URL = "http://nominatim.openstreetmap.org/search?format=json&limit=1&q=";
    final static String CALLBACK_PARAM = "json_callback";

    /**
     * Create the {@link Result} from the received {@link JavaScriptObject}.
     */
    @Override
    public GetLatLonResult insantiateResult(JavaScriptObject jsResult) {

        LatLonInfo latLonInfo = jsResult.cast();
        GetLatLonResult result = new GetLatLonResult();

        result.setHasData(latLonInfo.getCount() > 0);

        if (result.hasData()) {
            result.setDisplayName(latLonInfo.getDisplayName());
            result.setLat(Double.valueOf(latLonInfo.getLat()));
            result.setLon(Double.valueOf(latLonInfo.getLon()));
        }

        return result;
    }

    @Override
    public String getRequestURL(GetLatLonAction action) {
        return UriUtils.sanitizeUri(BASE_URL + action.getLocation());
    }

    @Override
    public String getCallbackParameter() {
        return CALLBACK_PARAM;
    }

    @Override
    public Class<GetLatLonAction> getActionType() {
        return GetLatLonAction.class;
    }

    /**
     * Overlay Java type for accessing contents of Javascript object
     * returned over JSONP.
     * 
     * @author Andrew Green
     */
    // TODO more error handling if JS object is malformed
    static private class LatLonInfo extends JavaScriptObject {

        protected LatLonInfo() {
        }

        public final native int getCount() /*-{
                                           return this.length;
                                           }-*/;

        public final native String getDisplayName() /*-{
                                                    return this[0].display_name;
                                                    }-*/;

        public final native String getLat() /*-{
                                            return this[0].lat;
                                            }-*/;

        public final native String getLon() /*-{
                                            return this[0].lon;
                                            }-*/;
    }
}