source: josm/src/org/openstreetmap/josm/io/OsmServerReader.java@ 75

package org.openstreetmap.josm.io;

import java.io.IOException;
import java.io.InputStreamReader;
import java.io.Reader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.Collection;
import java.util.LinkedList;

import org.jdom.JDOMException;
import org.openstreetmap.josm.Main;
import org.openstreetmap.josm.data.coor.LatLon;
import org.openstreetmap.josm.data.osm.DataSet;
import org.xml.sax.SAXException;

/**
 * This DataReader read directly from the REST API of the osm server.
 * 
 * @author imi
 */
public class OsmServerReader extends OsmConnection {

        /**
         * The boundings of the desired map data.
         */
        private final double lat1;
        private final double lon1;
        private final double lat2;
        private final double lon2;
        
        /**
         * Construct the reader and store the information for attaching
         */
        public OsmServerReader(double lat1, double lon1, double lat2, double lon2) {
                this.lon2 = lon2;
                this.lat2 = lat2;
                this.lon1 = lon1;
                this.lat1 = lat1;
        }


        /**
         * Retrieve raw gps waypoints from the server API.
         * @return A list of all primitives retrieved. Currently, the list of lists
         *              contain only one list, since the server cannot distinguish between
         *              ways.
         */
        public Collection<Collection<LatLon>> parseRawGps() throws IOException, JDOMException {
                String url = Main.pref.get("osm-server.url")+"/0.3/trackpoints?bbox="+lon1+","+lat1+","+lon2+","+lat2+"&page=";
                Collection<Collection<LatLon>> data = new LinkedList<Collection<LatLon>>();
                Collection<LatLon> list = new LinkedList<LatLon>();
                
                for (int i = 0;;++i) {
                        Reader r = getReader(url+i);
                        if (r == null)
                                break;
                        RawGpsReader gpsReader = new RawGpsReader(r);
                        Collection<Collection<LatLon>> allWays = gpsReader.parse();
                        boolean foundSomething = false;
                        for (Collection<LatLon> t : allWays) {
                                if (!t.isEmpty()) {
                                        foundSomething = true;
                                        list.addAll(t);
                                }
                        }
                        if (!foundSomething)
                                break;
                        r.close();
                }

                data.add(list);
                return data;
        }


        /**
         * Read the data from the osm server address.
         * @return A data set containing all data retrieved from that url
         */
        public DataSet parseOsm() throws SAXException, IOException {
                Reader r = getReader(Main.pref.get("osm-server.url")+"/0.3/map?bbox="+lon1+","+lat1+","+lon2+","+lat2);
                if (r == null)
                        return null;
                DataSet data = OsmReader.parseDataSet(r);
                r.close();
                return data;
        }


        /**
         * Open a connection to the given url and return a reader on the input stream
         * from that connection. In case of user cancel, return <code>null</code>.
         * @param url The exact url to connect to.
         * @return An reader reading the input stream (servers answer) or <code>null</code>.
         */
        private Reader getReader(String urlStr) throws IOException {
                System.out.println("download: "+urlStr);
                initAuthentication();
                URL url = new URL(urlStr);
                HttpURLConnection con = (HttpURLConnection)url.openConnection();
                con.setConnectTimeout(20000);
                if (con.getResponseCode() == 401 && isCancelled())
                        return null;
                return new InputStreamReader(con.getInputStream());
        }
}