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每次用户打开应用程序时，我们都会检查是否获得了他的当前位置。如果没有，应用程序会要求他在应用程序中启用位置LocationManager并返回应用程序。问题：有时，在某些手机中，即使启用了位置并且用户返回应用程序，位置仍然是null. 所以用户陷入了一个循环。为什么位置仍然为空？我能做些什么？

String locationContext = Context.LOCATION_SERVICE;

locationManager = (LocationManager) getSystemService(locationContext);
Location location = locationManager.getLastKnownLocation(locationProvider);

if (location != null) {
  double latitude = location.getLatitude();
  double longitude = location.getLongitude();

  final String lat = String.valueOf(latitude);
  final String lon = String.valueOf(longitude);

  System.out.println("Localisation:  " + lat + " " + lon);

  SharedPreferences preferences = PreferenceManager
      .getDefaultSharedPreferences(getBaseContext());
  String id = preferences.getString("id", null);
  new sendLocation().execute(id, lat, lon);
} else {
  System.out.println("NO LOCATION!!");
  AlertDialog.Builder alert = new AlertDialog.Builder(Home.this);

  alert.setTitle("Get started");
  alert.setMessage("We need your location to detect places nearby. Please enable -Wireless Networks- in your location settings to get started.");

  // Set an EditText view to get user input
  final TextView input = new TextView(Home.this);
  alert.setView(input);

  alert.setPositiveButton("Ok", new DialogInterface.OnClickListener() {

    public void onClick(DialogInterface dialog, int whichButton) {

      startActivity(new Intent(
          android.provider.Settings.ACTION_LOCATION_SOURCE_SETTINGS));

    }
  });

  alert.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {

    public void onClick(DialogInterface dialog, int whichButton) {
      // Canceled.
    }
  });

  alert.show();
}
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1 回答 1

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当用户在手机中启用位置功能时，Android 设备不一定会自动刷新位置信息。

为保证您能找回某种位置，您需要LocationListener为单个或多个更新注册一个。

locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 1000, 0.0f, this);

在“this”的主类中，添加implements LocationListener并添加以下方法：

public void onLocationChanged(Location location) {
    //This "location" object is what will contain updated location data
    //when the listener fires with a location update
}

public void onStatusChanged(String provider, int status, Bundle extras) {
    //Required by LocationListener - you can do nothing here
}

public void onProviderEnabled(String provider) {
    //Required by LocationListener - you can do nothing here
}

public void onProviderDisabled(String provider) {
    //Required by LocationListener - you can do nothing here
}

当您获得位置更新后，您可以通过以下方式禁用侦听器：

locationManager.removeUpdates(this);

更多关于 LocationListener 的文档：http: //developer.android.com/reference/android/location/LocationListener.html

于 2012-09-24T20:30:04.867 回答