Getting timezone offset from Google App Engine request headers?

Question

As per Google App Engine flexible docs, for any incoming request, as a service to the app, App Engine adds the following headers to all requests:

X-AppEngine-Country  as an ISO 3166-1 alpha-2 country code
X-AppEngine-Region    as an ISO-3166-2 standard
X-AppEngine-City
X-AppEngine-CityLatLong
X-Cloud-Trace-Context
X-Forwarded-For: [CLIENT_IP(s)], [global forwarding rule IP]
X-Forwarded-Proto [http | https]

Is there anyway I can get timezone offset using above info from request header using Java?

Answer 1

Add below to the pom.xml

  <dependency>
    <groupId>net.iakovlev</groupId>
    <artifactId>timeshape</artifactId>
    <version>2018d.1</version>
  </dependency>

And then run below type of code

package taruntest;

import net.iakovlev.timeshape.TimeZoneEngine;

import java.time.ZoneId;
import java.util.Optional;

public class ZoneInfo {
    public static TimeZoneEngine engine = null;
    private static Optional<ZoneId> ZoneID;

    public static void main(String[] args) {
        ZoneID = getZoneIdFromLatLong("12.971599,77.594563");
        System.out.println(ZoneID.toString());
    }

    public static Optional<ZoneId> getZoneIdFromLatLong(String latLong) {
        if (engine == null)
        {
            engine = TimeZoneEngine.initialize();
        }
        String[] latLongArr = latLong.split(",");
        double _lat = Double.parseDouble(latLongArr[0]);
        double _long = Double.parseDouble(latLongArr[1]);

        Optional<ZoneId> maybeZoneId = engine.query(_lat, _long);

        return maybeZoneId;
    }
}

The result is

Optional[Asia/Kolkata]

You can get your current coords using

https://mylocationtest.appspot.com/