org.jdal.gis.google.DirectionsService.java Source code

Introduction

Here is the source code for org.jdal.gis.google.DirectionsService.java

Source

/*
 * Copyright 2008-2011 the original author or authors.
 *
 * 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.jdal.gis.google;

import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.StringWriter;
import java.io.Writer;
import java.net.URL;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import net.sf.json.JSONArray;
import net.sf.json.JSONObject;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import com.vividsolutions.jts.geom.Coordinate;
import com.vividsolutions.jts.geom.GeometryFactory;
import com.vividsolutions.jts.geom.LineString;
import com.vividsolutions.jts.geom.MultiLineString;
import com.vividsolutions.jts.geom.PrecisionModel;
import com.vividsolutions.jts.geom.impl.CoordinateArraySequence;

public class DirectionsService {

    private static final Log log = LogFactory.getLog(DirectionsService.class);
    private String serverUrl = "http://maps.google.com/maps/api/directions/json";
    private GeometryFactory factory = new GeometryFactory(new PrecisionModel(), 4326);

    public DirectionsService() {
    }

    public MultiLineString getRoute(RouteRequest request) {

        try {
            URL url = new URL(serverUrl + "?" + request.toString());
            log.debug("Sending request: " + url.toString());
            return parseResponse(url.getContent());
        } catch (Exception e) {
            log.error(e);
        }
        return null;
    }

    @SuppressWarnings("rawtypes")
    private MultiLineString parseResponse(Object response) throws IOException {

        List<LineString> lines = new ArrayList<LineString>();

        String jsonString = responseToString(response);
        JSONObject json = JSONObject.fromObject(jsonString);

        if ("OK".equals(json.get("status"))) {
            JSONArray routes = json.getJSONArray("routes");
            JSONArray legs = routes.getJSONObject(0).getJSONArray("legs");
            JSONArray steps = legs.getJSONObject(0).getJSONArray("steps");

            if (log.isDebugEnabled())
                log.debug("Get route with " + steps.size() + " steps");

            Iterator iter = steps.iterator();

            while (iter.hasNext()) {
                JSONObject step = (JSONObject) iter.next();
                String polyline = step.getJSONObject("polyline").getString("points");
                LineString line = decodePolyline(polyline);
                lines.add(line);
            }
        }

        return new MultiLineString(lines.toArray(new LineString[] {}), factory);
    }

    private String responseToString(Object response) throws IOException {
        Writer writer = new StringWriter();
        InputStreamReader reader = new InputStreamReader((InputStream) response);
        int i;
        while ((i = reader.read()) != -1)
            writer.write(i);

        return writer.toString();

    }

    private LineString decodePolyline(String encoded) {

        List<Coordinate> coordinates = new ArrayList<Coordinate>();
        int index = 0, len = encoded.length();
        int lat = 0, lng = 0;

        while (index < len) {
            int b, shift = 0, result = 0;
            do {
                b = encoded.charAt(index++) - 63;
                result |= (b & 0x1f) << shift;
                shift += 5;
            } while (b >= 0x20);
            int dlat = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
            lat += dlat;

            shift = 0;
            result = 0;
            do {
                b = encoded.charAt(index++) - 63;
                result |= (b & 0x1f) << shift;
                shift += 5;
            } while (b >= 0x20);
            int dlng = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
            lng += dlng;

            coordinates.add(new Coordinate(lat / 1E5, lng / 1E5));
        }

        return new LineString(new CoordinateArraySequence(coordinates.toArray(new Coordinate[] {})), factory);
    }

    public static void main(String[] args) {
        RouteRequest request = new RouteRequest();
        request.setDestination(37.2582d, -6.9542);
        request.setOrigin(37.2546d, -6.9504d);

        DirectionsService service = new DirectionsService();
        service.getRoute(request);
    }

}