RxJava implementation to locate user with http://ip.taobao.com/service/getIpInfo.php?ip=myip

RxLocation.java

import org.json.JSONObject;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;

import rx.Observable;
import rx.Scheduler;
import rx.Subscriber;
import rx.schedulers.Schedulers;

public class RxLocation implements Observable.OnSubscribe<RxLocation.GeoInfo> {

    public static Observable<GeoInfo> create() {
        return create(Schedulers.io());
    }

    public static Observable<GeoInfo> create(Scheduler scheduler) {
        return Observable.create(new RxLocation(scheduler));
    }

    Scheduler mScheduler;

    private RxLocation(Scheduler scheduler) {
        mScheduler = scheduler;
    }

    @Override
    public void call(Subscriber<? super GeoInfo> subscriber) {
        mScheduler.createWorker().schedule(() -> {
            try {
                String jsonString = fetch();
                JSONObject json = new JSONObject(jsonString);
                if (json.getInt("code") != 0) {
                    throw new AssertionError("GeoInfo request must success with code 0");
                }
                json = json.getJSONObject("data");
                GeoInfo data = new GeoInfo();
                data.ip = json.getString("ip");
                data.country = json.getString("country");
                data.area = json.getString("area");
                data.region = json.getString("region");
                data.city = json.getString("city");
                data.isp = json.getString("isp");
                data.countryId = json.getString("country_id");
                data.areaId = json.getString("area_id");
                data.regionId = json.getString("region_id");
                data.cityId = json.getString("city_id");
                data.ispId = json.getString("isp_id");
                subscriber.onNext(data);
                subscriber.onCompleted();
            } catch (Exception e) {
                subscriber.onError(e);
            }
        });
    }

    private String fetch() throws IOException {
        HttpURLConnection conn = null;
        try {
            URL url = new URL("http://ip.taobao.com/service/getIpInfo2.php?ip=myip");
            conn = (HttpURLConnection) url.openConnection();
            conn.setRequestMethod("GET");
            conn.setRequestProperty("Content-length", "0");
            conn.setUseCaches(false);
            conn.setAllowUserInteraction(false);
            conn.setConnectTimeout(500);
            conn.setReadTimeout(4500);
            conn.connect();
            int status = conn.getResponseCode();
            switch (status) {
                case 200:
                case 201:
                    BufferedReader br = new BufferedReader(new InputStreamReader(conn.getInputStream()));
                    StringBuilder sb = new StringBuilder();
                    String line;
                    while ((line = br.readLine()) != null) {
                        sb.append(line).append("\n");
                    }
                    br.close();
                    return sb.toString();
                default:
                    throw new IOException("should always have status == 200");
            }
        } finally {
            if (conn != null) {
                conn.disconnect();
            }
        }
    }

    public static final class GeoInfo {
        public String ip;
        public String country;
        public String area;
        public String region;
        public String city;
        public String isp;
        public String countryId;
        public String areaId;
        public String regionId;
        public String cityId;
        public String ispId;
    }

}