我的目标是使用Google Places API进行自动完成预测，现在我想制定一种算法，该算法将获取当前位置的纬度和经度，并预测仅在100-200公里半径内的地点。
因此，目前我已获取了用户当前位置的纬度和经度，如何设置100-200公里的半径呢？
private void getCurrentLocation() {
mLastLocation = LocationServices.FusedLocationApi
.getLastLocation(mGoogleApiClient);
if (mLastLocation != null) {
double latitude = mLastLocation.getLatitude();
double longitude = mLastLocation.getLongitude();
mLatLonBounds = new LatLngBounds(new LatLng(latitude,longitude),
new LatLng(latitude,longitude));
Log.d("myTag","lat = "+mLatLonBounds.northeast.latitude+" ,lon = "+mLatLonBounds.northeast.longitude);
//Log.d("myTag","lat = "+mLatLonBounds.southwest.latitude+" ,lon = "+mLatLonBounds.southwest.longitude);
}else {
//some code
}
}
以下是我如何设置自动预测的边界:
@Nullable
private ArrayList<AutoCompletePlace> getAutocomplete(CharSequence constraint) {
if (mGoogleApiClient.isConnected()) {
Log.i(Constants.AUTO_COMPLETE_TAG, "Starting autocomplete query for: " + constraint);
// Submit the query to the autocomplete API and retrieve a PendingResult that will
// contain the results when the query completes.
PendingResult<AutocompletePredictionBuffer> results = Places.GeoDataApi
.getAutocompletePredictions(mGoogleApiClient, constraint.toString(),
**mBounds**, mPlaceFilter);
// This method should have been called off the main UI thread. Block and wait for at most 60s
// for a result from the API.
AutocompletePredictionBuffer autocompletePredictions = results.await(60, TimeUnit.SECONDS);
// Confirm that the query completed successfully, otherwise return null
final Status status = autocompletePredictions.getStatus();
if (!status.isSuccess()) {
Toast.makeText(getContext(), "Error contacting API: " + status.toString(),
Toast.LENGTH_SHORT).show();
Log.e(Constants.AUTO_COMPLETE_TAG, "Error getting autocomplete prediction API call: " + status.toString());
autocompletePredictions.release();
return null;
}
Log.i(Constants.AUTO_COMPLETE_TAG, "Query completed. Received " + autocompletePredictions.getCount()
+ " predictions.");
// Copy the results into our own data structure, because we can't hold onto the buffer.
// AutocompletePrediction objects encapsulate the API response (place ID and description).
Iterator<AutocompletePrediction> iterator = autocompletePredictions.iterator();
ArrayList resultList = new ArrayList<>(autocompletePredictions.getCount());
while (iterator.hasNext()) {
AutocompletePrediction prediction = iterator.next();
// Get the details of this prediction and copy it into a new PlaceAutocomplete object.
resultList.add(new AutoCompletePlace(prediction.getPlaceId(),
prediction.getDescription()));
}
// Release the buffer now that all data has been copied.
autocompletePredictions.release();
return resultList;
}
Log.e(Constants.AUTO_COMPLETE_TAG, "Google API client is not connected for autocomplete query.");
return null;
我的当前位置示例为48.6180288,22.2984587。
更新：在Francois Wouts给出答案之前，我在stackoverflow上找到了另一种解决方案，您也可以使用它。
public static final LatLngBounds setBounds(Location location, int mDistanceInMeters ){
double latRadian = Math.toRadians(location.getLatitude());
double degLatKm = 110.574235;
double degLongKm = 110.572833 * Math.cos(latRadian);
double deltaLat = mDistanceInMeters / 1000.0 / degLatKm;
double deltaLong = mDistanceInMeters / 1000.0 / degLongKm;
double minLat = location.getLatitude() - deltaLat;
double minLong = location.getLongitude() - deltaLong;
double maxLat = location.getLatitude() + deltaLat;
double maxLong = location.getLongitude() + deltaLong;
Log.d("Location", "Min: " + Double.toString(minLat) + "," + Double.toString(minLong));
Log.d("Location","Max: "+Double.toString(maxLat)+","+Double.toString(maxLong));
// Set up the adapter that will retrieve suggestions from the Places Geo Data API that cover
// the entire world.
return new LatLngBounds(new LatLng(minLat,minLong),new LatLng(maxLat,maxLong));