OpenScienceMap ExtendedMapView. Uses my custom preferences cache wrapper, just use your own implementation

ExtendedMapView.java

public class ExtendedMapView extends MapView {

    private BaseContext baseContext;

    public ExtendedMapView(Context context) {
        super(context);
        baseContext = (BaseContext) context.getApplicationContext();
        restorePosition();
    }

    public ExtendedMapView(Context context, AttributeSet attributeSet) {
        super(context, attributeSet);
        baseContext = (BaseContext) context.getApplicationContext();
        restorePosition();
    }

    private void restorePosition() {
        baseContext.mapsCache.restore();
        if (baseContext.mapsCache.mapScale != 1 ||
                baseContext.mapsCache.latitude != 0 ||
                baseContext.mapsCache.longitude != 0) {

            MapPosition mapPosition = new MapPosition();
            mapPosition.setPosition(baseContext.mapsCache.latitude / 1E6, baseContext.mapsCache.longitude / 1E6);
            mapPosition.setScale(baseContext.mapsCache.mapScale);

            mMap.setMapPosition(mapPosition);
        }

    }

    public void onPause() {
        MapPosition mapPosition = new MapPosition();
        mMap.viewport().getMapPosition(mapPosition);
        GeoPoint geoPoint = mapPosition.getGeoPoint();

        baseContext.mapsCache.latitude = geoPoint.latitudeE6;
        baseContext.mapsCache.longitude = geoPoint.longitudeE6;
        baseContext.mapsCache.mapScale = (float) mapPosition.scale;

        baseContext.mapsCache.save();

        mMap.pause(true);
    }

    public void onResume() {
        mMap.pause(false);
    }
}