How to find the closest city using android geolocation to get the weather data-CodePudding

I'm making a weather forcast app for my uni project and I wonder how to get the name of the closest city so I can get the weather data from sites like OpenWeatherMap, is there maybe other site that can return the data of the city that is closest to me?

CodePudding user response：

1. Using LocationManager, get the lat, lng of current location.

LocationManager mLocationManager = (LocationManager) mContext.getSystemService(Context.LOCATION_SERVICE);

Location location = mLocationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);

2. Use Geocoder api, to fetch the address list based on your current lat, lng.

Geocoder gcd = new Geocoder(context, Locale.getDefault());
List<Address> addresses = gcd.getFromLocation(location.getLatitude(), 
 location.getLongitude(), 1);
if (addresses.size() > 0) {
    for(Address adr : addresses){
     if(adr != null && adr.getLocality().length() > 0){
       cityName = adr.getLocality()
        break;
}
}

CodePudding user response：

Let's break down problem as below:

1. Request User location coordinate

With Geolocation API you can request user location. For sake of simplicity, let we use EXPO SDK as it provides a unified API for common tasks.

import * as Location from "expo-location";

export const hasLocationServiceEnable = async () =>
  await Location.hasServicesEnabledAsync();

const getUserLocation = async () => {
  let result = null;
  const isLocationAccessEnabled = await hasLocationServiceEnable();

  if (!isLocationAccessEnabled) {
    return result;
  } else {
    let { status } = await Location.requestForegroundPermissionsAsync();
    if (status !== "granted") {
      return result;
    } else {
      try {
        let { coords } = await Location.getCurrentPositionAsync({});
        result = coords || null;
      } catch (error) {
        console.log(error);
      }

      return result;
    }
  }
};

export default getUserLocation;

2. Geocode coordinates to physical address names

Geocoding requires third-party services, let us use Google Map Geocoding API and has react native wrapper package.


import Geocoder from "react-native-geocoding";


// Initialize the module (needs to be done only once)
Geocoder.init("xxxxxxxxxxxxxxxxxxxxxxxxx"); // use a valid API key

export const getPlaceFromCoordinate = async ({ longitude, latitude }) => {
  let place = null;
  const response = await Geocoder.from(
    parseFloat(latitude),
    parseFloat(longitude)
  );
  address = response.results[0].formatted_address || null;
  return address;
};
export default getPlaceFromCoordinate;

3. Request place weather data


export const WEATHER_API = `http://api.openweathermap.org/data/2.5/weather?APPID=${"YOUR_OPEN_WEATHER_MAP_API_KEY"}&units=metric`;


export const getWeatherForecast = (place) => {
  const requestUrl = `${WEATHER_API}&q=${place}`;
  let forecast = null;
  try {
    const todayForecast = await fetch(`${requestUrl}`);
    forecast = await todayForecast.json();
    return forecast;
  } catch (e) {
    console.log(e);
    return forecast;
  }
};

4. Connect all together


const getPlaceWeather = async () => {
  try {
    const coordinate = await getUserLocation();
    if (!coordinate) return;
    const place = await getPlaceFromCoordinate(coordinate);
    if (!place) return;

    const placeForecast = await getWeatherForecast(place);

    console.log({ placeForecast });
  } catch (error) {
    console.log(error);
  }
};

This is a high-level solution, there are a lot of features, I didn't cover including show weather icons, weather widget, and more.