我想做什么：
我正试图开发一个应用程序，它只需要在一个活动开始时获取用户的位置。因此，仅当用户在活动范围内时，位置才会通过网络或GPS更新。相应地，用户可以选择室内地图。
我的问题是什么：
然而，我发现该应用程序始终使用历史位置，并且从未更新位置。我怀疑我的
location = locationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER)
有问题，但我不确定问题出在哪里。
相关代码片段：
在我的Activity中，我有：
locationDetector = new LocationDetector(MapSelectionActivity.this);
// try to get the current location
if (locationDetector.checkLocationServiceAvailability()) {
location = locationDetector.getLocation();
if (location != null) {
latitude = location.getLatitude();
longitude = location.getLongitude();
}
Log.d("MapSelectionActivity", latitude + " " + longitude);
//locationDetector.stopLocalization(); // stop the localization to save the energy
} else { // if no location service, requires the user to turn GPS on
locationDetector.showSettingsAlert();
}
我的LocationDetector类如下：
public final class LocationDetector implements LocationListener {
private final Context mContext;
private boolean isNetworkEnabled = false;
private boolean isGPSEnabled = false;
private boolean canGetLocation = false;
private Location location;
private String providerUsed;
// The minimum distance to change Updates in meters
private static final long MIN_DISTANCE_CHANGE_FOR_UPDATES = 0; // 0 meters
// The minimum time between updates in milliseconds
private static final long MIN_TIME_BW_UPDATES = (long) (1000 * 60 * 0.5); // 0.5 minute
// Declaring a Location Manager
protected LocationManager locationManager;
// constructor
public LocationDetector(Context context) {
this.mContext = context;
locationManager = (LocationManager) mContext.getSystemService(Context.LOCATION_SERVICE);
}
// NOTE call checkLocationServiceAvailability(); first before calling this!
public Location getLocation() {
// I SUSPECT SOMETHING IS WRONG HERE
if (isNetworkEnabled) { // use network
locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, MIN_TIME_BW_UPDATES, MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
Log.d("LocationDetector", "Using Network");
if (locationManager != null) {
location = locationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
}
providerUsed = "Network";
} else if (isGPSEnabled) { // use GPS
if (location == null) {
locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, MIN_TIME_BW_UPDATES, MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
Log.d("LocationDetector", "Using GPS");
if (locationManager != null) {
location = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
}
}
providerUsed = "GPS";
} else { // neither the network nor the GPS is on
providerUsed = null;
Toast.makeText(mContext, "Location service is unavaliable", Toast.LENGTH_SHORT).show();
}
return location;
}
// call this to restart requesting the detecting
public void startLocalization() {
if (locationManager != null) {
locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, MIN_TIME_BW_UPDATES, MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, MIN_TIME_BW_UPDATES, MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
}
}
// call this to stop the detecting to save power
public void stopLocalization() {
if (locationManager != null) {
locationManager.removeUpdates(LocationDetector.this);
}
}
// check location service availability
public boolean checkLocationServiceAvailability() {
// check GPS on or off
isGPSEnabled = locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);
// check Internet access
ConnectivityManager connectivityManager = (ConnectivityManager) mContext.getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo netInfo = connectivityManager.getActiveNetworkInfo();
if (netInfo != null && netInfo.isConnected()) {
isNetworkEnabled = true;
} else {
isNetworkEnabled = false;
}
if (isGPSEnabled || isNetworkEnabled) {
canGetLocation = true;
} else {
canGetLocation = false;
}
return canGetLocation;
}
public String getLocationProvider() {
return providerUsed;
}
// show alert dialog to direct the users to the settings
public void showSettingsAlert() {
AlertDialog.Builder alertDialog = new AlertDialog.Builder(mContext);
// make it uncancellable
alertDialog.setCancelable(false);
// Setting Dialog Title
alertDialog.setTitle("Forgot to turn GPS on?");
// Setting Dialog Message
alertDialog.setMessage("Currently there is no Internet access.\n\nLocalization requires GPS when Internet is unavailiable.\n\nDo you want to enable GPS so as to proceed?");
// On pressing Settings button
alertDialog.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
mContext.startActivity(intent);
Toast.makeText(mContext, "After enabling GPS, press the physical 'Back' button to return", Toast.LENGTH_LONG).show();
}
});
// on pressing cancel button
alertDialog.setNegativeButton("No", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
dialog.cancel();
Toast.makeText(mContext, "No location service, please choose map manually", Toast.LENGTH_LONG).show();
}
});
// Showing Alert Message
alertDialog.show();
}
@Override
public void onLocationChanged(Location _location) {
// IT NEVER GETS CALLED
location = _location;
// update the text view
MapSelectionActivity.coordinatesTextView.setText("(" + Math.round(location.getLatitude() * 1000) / 1000.0 + ", " + Math.round(location.getLongitude() * 1000) / 1000.0 + ")");
// update the marker on Google Maps
MapSelectionActivity.googleMap.clear();
MapSelectionActivity.googleMap.addMarker(new MarkerOptions().position(new LatLng(location.getLatitude(), location.getLongitude())).title("I am here!"));
MapSelectionActivity.googleMap.moveCamera(CameraUpdateFactory.newLatLngZoom(new LatLng(location.getLatitude(), location.getLongitude()), 15)); // 15 is the approporiate zooming level
// re-suggest the map
int recommendedMapSequenceNumber = MapSelectionActivity.mapDatabase.getMapSequenceNumber(location.getLatitude(), location.getLongitude());
MapSelectionActivity.recommendedMapTextView.setTextColor(Color.parseColor("red"));
if (recommendedMapSequenceNumber == -1) { // the so-called nearest is still too far
Toast.makeText(mContext, "Please manually select one to proceed", Toast.LENGTH_LONG).show();
MapSelectionActivity.recommendedMapTextView.setText("No recommended maps");
MapSelectionActivity.autoSelectButton.setEnabled(false);
} else { // suggest a map
Toast.makeText(mContext, "One suitable map found", Toast.LENGTH_SHORT).show();
MapSelectionActivity.recommendedMapTextView.setText(MapSelectionActivity.mapDatabase.getMapName(recommendedMapSequenceNumber));
}
Toast.makeText(mContext, "New location detected", Toast.LENGTH_SHORT).show();
}
@Override
public void onProviderDisabled(String provider) {
}
@Override
public void onProviderEnabled(String provider) {
}
@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
}
}
我从onLocationChanged()中无法看到Toast，这意味着它从未被调用！同时，从地图上可以看出位置没有更新。
if (locationManager != null) { location = locationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER); }，然后再尝试执行您的代码。 - Vigbyor