LocationManager发送null

Question

我正在使用谷歌地图V2，我试图获取当前位置。但它总是返回null。

代码

locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
Criteria criteria = new Criteria();
provider = locationManager.getBestProvider(criteria, false);
Location location = locationManager.getLastKnownLocation(provider); 

每次我收到location null。我的GPS在我的设备上工作正常可以帮助我。

Answer 1

根据getLastKnownLocation documentation：

  

如果当前禁用了提供程序，则返回null。

当您使用getBestProvider(criteria, false)时，您说您允许未启用的提供程序（false表示的意思） - 如果您只想查看已启用的提供程序，请将其切换为true （这将确保getLastKnownLocation不返回null）。

请注意，getLastKnownLocation可能已过期，如果您需要获取最近的位置，您可能仍希望查找位置更新。

Answer 2

试试这个：

全球范围内：

private LocationManager location_manager;
    // flag for GPS status
    boolean isGPSEnabled = false;

    // flag for network status
    boolean isNetworkEnabled = false;

    // flag for GPS status
    boolean canGetLocation = false;

    Location location = null; // location
    double latitude; // latitude
    double longitude; // longitude

    // The minimum distance to change Updates in meters
    private static final long MIN_DISTANCE_CHANGE_FOR_UPDATES = 10; // 10 meters

    // The minimum time between updates in milliseconds
    private static final long MIN_TIME_BW_UPDATES = 1000 * 60 * 1; // 1 minute

从任何地方调用此方法：

public Location getCurrentLatLong(Context conext,LocationListener con) 
    {
        try 
        {
            location_manager = (LocationManager) ((Activity) con)
                    .getSystemService(Context.LOCATION_SERVICE);

            // getting GPS status
            isGPSEnabled = location_manager
                    .isProviderEnabled(LocationManager.GPS_PROVIDER);

            // getting network status
            isNetworkEnabled = location_manager
                    .isProviderEnabled(LocationManager.NETWORK_PROVIDER);

            if (!isGPSEnabled && !isNetworkEnabled)
            {
                // no network provider is enabled
                Toast.makeText(conext, "No provider is enabled", Toast.LENGTH_SHORT).show();
            } 
            else
            {
                this.canGetLocation = true;
                if (isNetworkEnabled) 
                {
                    location_manager.requestLocationUpdates(
                            LocationManager.NETWORK_PROVIDER,
                            MIN_TIME_BW_UPDATES,
                            MIN_DISTANCE_CHANGE_FOR_UPDATES, con);
                    Log.d("Network", "Network Enabled");
                    if (location_manager != null)
                    {
                        location = location_manager
                                .getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
                        if (location != null) 
                        {
                            latitude = location.getLatitude();
                            longitude = location.getLongitude();
                        }
                    }
                }
                // if GPS Enabled get lat/long using GPS Services
                if (isGPSEnabled) 
                {
                    if (location == null)
                    {
                        location_manager.requestLocationUpdates(
                                LocationManager.GPS_PROVIDER,
                                MIN_TIME_BW_UPDATES,
                                MIN_DISTANCE_CHANGE_FOR_UPDATES, con);
                        Log.d("GPS", "GPS Enabled");
                        if (location_manager != null) 
                        {
                            location = location_manager
                                    .getLastKnownLocation(LocationManager.GPS_PROVIDER);
                            if (location != null)
                            {
                                latitude = location.getLatitude();
                                longitude = location.getLongitude();
                            }
                        }
                    }
                }
            }

        } 
        catch (Exception e) 
        {
            e.printStackTrace();
        }

        return location;
    }

Answer 3

有不同的方法。首先，请确保您的清单中包含所有必需的权限：

<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />

如果您只想要一个大概的位置，您可以获得最后一个位置（GPS或网络）

if(_locationManager != null)
{
    if(_locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER) != null)
        return new Location(_locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER),true);

    else if(_locationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER) != null)
        return new Location(_locationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER),true);      
}