com.nanosheep.bikeroute.parser.GoogleElevationParser.java Source code

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Here is the source code for com.nanosheep.bikeroute.parser.GoogleElevationParser.java

Source

package com.nanosheep.bikeroute.parser;

import android.util.Log;
import com.nanosheep.bikeroute.constants.BikeRouteConsts;
import com.nanosheep.bikeroute.utility.route.Route;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;

/**
 * Parse a google elevations json object to an xy data series.
 * 
 * This file is part of BikeRoute.
 * 
 * Copyright (C) 2011  Jonathan Gray
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 * 
 * @author jono@nanosheep.net
 * @version Jun 25, 2010
 */
public class GoogleElevationParser extends XMLParser implements Parser {
    /** Distance covered. **/
    private double distance;
    /** Route to work on. **/
    private final Route route;

    public GoogleElevationParser(final String feedUrl, final Route route) {
        super(feedUrl);
        this.route = route;
    }

    /**
     * Parses a url pointing to a Google JSON object to a Route object.
     * @return a Route object based on the JSON object.
     */

    @Override
    public Route parse() {
        // turn the stream into a string
        final String result = convertStreamToString(this.getInputStream());
        try {
            //Tranform the string into a json object
            final JSONObject json = new JSONObject(result);
            //Get the results object
            final JSONArray jsonResult = json.getJSONArray("results");
            JSONObject location = jsonResult.getJSONObject(0).getJSONObject("location");
            //Get the first point, use it as a basis for calculating the distance
            //Store incremented distance with retrieved elevation.
            double lastLat = location.getDouble("lat");
            double lastLng = location.getDouble("lng");
            for (int i = 0; i < jsonResult.length(); i++) {
                location = jsonResult.getJSONObject(i).getJSONObject("location");
                final double lat = location.getDouble("lat");
                final double lng = location.getDouble("lng");
                final double elevation = jsonResult.getJSONObject(i).getDouble("elevation");
                distance += pointDiff(lat, lng, lastLat, lastLng);
                lastLat = lat;
                lastLng = lng;
                route.addElevation(elevation, distance);
            }
        } catch (JSONException e) {
            Log.e(e.getMessage(), "Google Elevation Parser - " + feedUrl);
        }
        return route;
    }

    /**
     * Convert an inputstream to a string.
     * @param input inputstream to convert.
     * @return a String of the inputstream.
     */

    private static String convertStreamToString(final InputStream input) {
        final BufferedReader reader = new BufferedReader(new InputStreamReader(input));
        final StringBuilder sBuf = new StringBuilder();

        String line = null;
        try {
            while ((line = reader.readLine()) != null) {
                sBuf.append(line);
            }
        } catch (IOException e) {
            Log.e(e.getMessage(), "Google parser, stream2string");
        } finally {
            try {
                input.close();
            } catch (IOException e) {
                Log.e(e.getMessage(), "Google parser, stream2string");
            }
        }
        return sBuf.toString();
    }

    /**
     * Calculate the distance between two points of the earth using
     * the haversine formula.
     * @param lat Starting latitude.
     * @param lng Starting longitude.
     * @param latA End latitude,
     * @param lngA End longitude.
     * @return The distance between the two points in m.
     */

    private double pointDiff(final double lat, final double lng, final double latA, final double lngA) {
        final double dLat = Math.toRadians(latA - lat);
        final double dLon = Math.toRadians(lngA - lng);
        final double a = Math.sin(dLat / 2) * Math.sin(dLat / 2) + Math.cos(Math.toRadians(lat))
                * Math.cos(Math.toRadians(latA)) * Math.sin(dLon / 2) * Math.sin(dLon / 2);
        final double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
        return BikeRouteConsts.EARTH_RADIUS * c * 1000;
    }
}