private void fetchDataFromNetWork(final CityEntity city) {
    Api.getIApi().getWeather(city.name, ApiKey.HE_KEY)
            .subscribeOn(Schedulers.io())
            .observeOn(AndroidSchedulers.mainThread())
            .filter(new Func1<WeatherData, Boolean>() {
                @Override
                public Boolean call(final WeatherData weatherData) {
                    boolean success = weatherData.weathers.get(0).status.equals("ok");
                    return success;
                }
            })
            .map(new Func1<WeatherData, Weather>() {
                @Override
                public Weather call(WeatherData weatherData) {
                    return weatherData.weathers.get(0);
                }
            })
            .doOnNext(new Action1<Weather>() {
                @Override
                public void call(Weather weather) {
                    mACache.put(city.name, weather);
                    SystemUtils.saveRefreshTime(WeatherActivity.this);
                }
            })
            .subscribe(new Subscriber<Weather>() {
                ...
                updateView(weather);
                ...
            });
}