多个设备的地理定位

Question

I am currently making an app that requires me to geolocalize multiple devices on the same map. The user clicks on an imageview, a new Activity pops up and a map is shown with the position of all of the app users. However after looking through the web I didn't find anything helpful.

I was wondering what was the better solution :

1) Each time a user starts the "MapsActivity" it triggers notifications to each user so it can request its position 2) Every 30 seconds each user's position is updated in a database and each time a user starts the "MapsActivity" it sends a query to the database => This solution might drain the battery ...

Thanks for your help

Answer 1

Make sure that when a users starts the MapsActivity , you want location of all users to be displayed. If you want the location of all users displayed then that would'nt be geolocalization at all, it will be simple geolocation.For now

For location of all users

Figure out what precision of location of the users you need. If you need Highly precise location then you will have to use the method you descibed above which apprently drains battery.

1) Each time a user starts the "MapsActivity" it triggers notifications to each user so it can request its position 2) Every 30 seconds each user's position is updated in a database and each time a user starts the "MapsActivity" it sends a query to the database => This solution might drain the battery

If highly precise data is not required, then periodically the users can send a geohash of their location to the servers and the servers can store data in > form. When a user starts the MapsActivity, geohash will be calculated locally and a query will be sent to the server which will return approximate positions in return. The only advantage you have here is that the period can be larger ie users can ping the servers every 5 minutes instead of 30 seconds thus saving bettery.

For location of all users

Use the similar geohash technique and ping the servers with geohashes of users' location. Then while retrieving, calculate the aproximate geohash using levenshtein distance and return users belonging to all of these approximate geohashes.

Heres some resources you might find useful

Geohash information

Geohash website

Geohash API for Java