requestLocationUpdates() method is giving updates without change in location - Android

问题

I have used onLocationChanged method of LocationListener for detecting change in location of my device. In requestLocationUpdates method I have set minimum Time = 5 seconds and minimum Distance = 2 meters, but requestLocationUpdates method is giving me updates even when my device is not moved at all (placed stationary). So please tell what is the issue with my code?

This my code:

public class LocationDetector implements LocationListener {
    @Override
    public void onLocationChanged(Location location) {
        Log.d("GPS: ",location.getLatitude()+", "+location.getLongitude());
    }

.

LocationManager manager = (LocationManager)getSystemService(Context.LOCATION_SERVICE);

.

manager.requestLocationUpdates("gps", 5000, 2, new LocationDetector());

回答1:

The GPS location can fluctuate. If you actually log the locations that you receive, you'll probably see that the location actually changes by 2 meters or more whenever a location update comes.

Edit: Ideas for dealing with the fluctuation added:

How to deal with GPS fluctuation depends on your application's needs. Some possible ideas include:

If you don't need a really accurate location, then use a higher distance limit in the requestLocationUpdates() call to not receive updates for very small location changes. You can think what's the absolutely necessary accuracy required by your use case and then use the highest possible distance limit.

If you don't expect the location to change very quickly or you don't need to react to location changes very quickly, then use a higher time limit in the requestLocationUpdates() call. This also makes sense if you have some very heavy code triggered by onLocationChanged() like if you always fetch some data over the network (reverse geocoding etc.).

The time limit also has more impact on the battery usage. Android documentation says:

...it is more difficult for location providers to save power using the minDistance parameter, so minTime should be the primary tool to conserving battery life.

If you really need an accurate location then there are some ways to decrease the fluctuation.

First of all the Location object received in onLocationChanged() usually has an estimated accuracy available by calling the Location.getAccuracy() method. You can simply ignore any location updates that have very poor accuracy (compared to the accuracies of previous location updates).

You can also do some filtering if you have a short buffer of the most recent locations. Calculating an average will reduce the amount of sudden changes but it also increases the response time. That is: a rapid change in the location will completely show up in the averaged location data only after some time. (Of course the averaged data starts to move towards the location right away, but it takes a while.) Also it will "let the spikes trough" to some amount.

If a fast response time is important and any major "spikes" in the data should be eliminated, then calculating the median is a better option. It will not smooth out the small changes in the data that much, but random spikes can be filtered out. If there's a real (permanent) sudden change in location, then the median filtering reacts to that with only a very small delay.

(These things are easy to try out in your favourite spreadsheet application.)

来源：https://stackoverflow.com/questions/37094660/requestlocationupdates-method-is-giving-updates-without-change-in-location-a