如何在 Android 中获取位置管理器的最后已知位置？

How to get last known location for Location manager in Android?

提问by Aditi K

I am using simple location managerobject to get lastKnownLocation()of device but getting null objectin returncan any one tell me why ?

我正在使用简单的位置管理器对象来获取设备的lastKnownLocation()但得到空对象作为回报谁能告诉我为什么？

Code :

代码 ：

public Location getLocation() {
    LocationManager locationManager = (LocationManager) this.getSystemService(Context.LOCATION_SERVICE);        
    if (locationManager != null) {          
        Location lastKnownLocationGPS = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
        if (lastKnownLocationGPS != null) {             
            return lastKnownLocationGPS;
        } else {                
            Location loc =  locationManager.getLastKnownLocation(LocationManager.PASSIVE_PROVIDER);
            System.out.println("1::"+loc);----getting null over here
            System.out.println("2::"+loc.getLatitude());
            return loc;
        }
    } else {            
        return null;
    }
}
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.location);
    getLocation();-----calling service

 }

permissions given :

授予的权限：

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

so is anything missing to set up? I have checked my location service is on in device please give some links for working examples

那么有什么需要设置的吗？我已经检查了我的位置服务是否在设备中，请提供一些工作示例的链接

采纳答案by Aditi K

Silly thing as answer to this ...I restarted my device ...and it worked...Please ensure that your service for location are enabled and working properly

愚蠢的事情作为这个答案......我重新启动了我的设备......它工作......请确保您的位置服务已启用并正常工作

回答by Archit Jain

The thing i use to get Location with Name of the placeis

我用来获取带有地点名称的位置的东西是

GPSTracker gpsTracker = new GPSTracker(CameraActivity.this);
String stringLatitude = "", stringLongitude = "", nameOfLocation="";
    if (gpsTracker.canGetLocation()) {
        stringLatitude = String.valueOf(gpsTracker.latitude);
        stringLongitude = String.valueOf(gpsTracker.longitude);
        nameOfLocation = ConvertPointToLocation(stringLatitude,stringLongitude);
    }

public String ConvertPointToLocation(String Latitude, String Longitude) {
    String address = "";
    Geocoder geoCoder = new Geocoder(getBaseContext(), Locale.getDefault());
    try {
        List<Address> addresses = geoCoder.getFromLocation(
                Float.parseFloat(Latitude), Float.parseFloat(Longitude), 1);

        if (addresses.size() > 0) {
            for (int index = 0; index < addresses.get(0)
                    .getMaxAddressLineIndex(); index++)
                address += addresses.get(0).getAddressLine(index) + " ";
        }
    } catch (IOException e) {
        e.printStackTrace();
    }

    return address;
}

GPSTracker.java

GPS追踪器.java

package in.appology.lss;

import java.io.IOException;
import java.util.List;
import java.util.Locale;

import android.app.AlertDialog;
import android.app.Service;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.location.Address;
import android.location.Geocoder;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.os.IBinder;
import android.provider.Settings;
import android.util.Log;

/**
 * Create this Class from tutorial :
 * http://www.androidhive.info/2012/07/android-gps-location-manager-tutorial
 * 
 * For Geocoder read this :
 * http://stackoverflow.com/questions/472313/android-reverse
 * -geocoding-getfromlocation
 * 
 */

public class GPSTracker extends Service implements LocationListener {
private final Context mContext;

// flag for GPS Status
boolean isGPSEnabled = false;

// flag for network status
boolean isNetworkEnabled = false;

boolean canGetLocation = false;

Location location;
double latitude;
double longitude;

// The minimum distance to change updates in metters
private static final long MIN_DISTANCE_CHANGE_FOR_UPDATES = 10; // 10
                                                                // metters

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

// Declaring a Location Manager
protected LocationManager locationManager;

public GPSTracker(Context context) {
    this.mContext = context;
    getLocation();
}

public Location getLocation() {
    try {
        locationManager = (LocationManager) mContext
                .getSystemService(LOCATION_SERVICE);

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

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

        if (!isGPSEnabled && !isNetworkEnabled) {
            // no network provider is enabled
        } else {
            this.canGetLocation = true;

            // First get location from Network Provider
            if (isNetworkEnabled) {
                locationManager.requestLocationUpdates(
                        LocationManager.NETWORK_PROVIDER,
                        MIN_TIME_BW_UPDATES,
                        MIN_DISTANCE_CHANGE_FOR_UPDATES, this);

                Log.d("Network", "Network");

                if (locationManager != null) {
                    location = locationManager
                            .getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
                    updateGPSCoordinates();
                }
            }

            // if GPS Enabled get lat/long using GPS Services
            if (isGPSEnabled) {
                if (location == null) {
                    locationManager.requestLocationUpdates(
                            LocationManager.GPS_PROVIDER,
                            MIN_TIME_BW_UPDATES,
                            MIN_DISTANCE_CHANGE_FOR_UPDATES, this);

                    Log.d("GPS Enabled", "GPS Enabled");

                    if (locationManager != null) {
                        location = locationManager
                                .getLastKnownLocation(LocationManager.GPS_PROVIDER);
                        updateGPSCoordinates();
                    }
                }
            }
        }
    } catch (Exception e) {
        // e.printStackTrace();
        Log.e("Error : Location",
                "Impossible to connect to LocationManager", e);
    }

    return location;
}

public void updateGPSCoordinates() {
    if (location != null) {
        latitude = location.getLatitude();
        longitude = location.getLongitude();
    }
}

/**
 * Stop using GPS listener Calling this function will stop using GPS in your
 * app
 */

public void stopUsingGPS() {
    if (locationManager != null) {
        locationManager.removeUpdates(GPSTracker.this);
    }
}

/**
 * Function to get latitude
 */
public double getLatitude() {
    if (location != null) {
        latitude = location.getLatitude();
    }

    return latitude;
}

/**
 * Function to get longitude
 */
public double getLongitude() {
    if (location != null) {
        longitude = location.getLongitude();
    }

    return longitude;
}

/**
 * Function to check GPS/wifi enabled
 */
public boolean canGetLocation() {
    return this.canGetLocation;
}

/**
 * Function to show settings alert dialog
 */
public void showSettingsAlert() {
    AlertDialog.Builder alertDialog = new AlertDialog.Builder(mContext);

    // Setting Dialog Title
    alertDialog.setTitle("GPS");

    // Setting Dialog Message
    alertDialog
            .setMessage("Please enable location in settings for accurate results!");

    // On Pressing Setting button
    alertDialog.setPositiveButton("Settings",
            new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    Intent intent = new Intent(
                            Settings.ACTION_LOCATION_SOURCE_SETTINGS);
                    mContext.startActivity(intent);
                }
            });

    // On pressing cancel button
    alertDialog.setNegativeButton("Cancel",
            new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    dialog.cancel();
                }
            });

    alertDialog.show();
}

/**
 * Get list of address by latitude and longitude
 * 
 * @return null or List<Address>
 */
public List<Address> getGeocoderAddress(Context context) {
    if (location != null) {
        Geocoder geocoder = new Geocoder(context, Locale.ENGLISH);
        try {
            List<Address> addresses = geocoder.getFromLocation(latitude,
                    longitude, 1);
            return addresses;
        } catch (IOException e) {
            // e.printStackTrace();
            Log.e("Error : Geocoder", "Impossible to connect to Geocoder",
                    e);
        }
    }

    return null;
}

/**
 * Try to get AddressLine
 * 
 * @return null or addressLine
 */
public String getAddressLine(Context context) {
    List<Address> addresses = getGeocoderAddress(context);
    if (addresses != null && addresses.size() > 0) {
        Address address = addresses.get(0);
        String addressLine = address.getAddressLine(0);

        return addressLine;
    } else {
        return null;
    }
}

/**
 * Try to get Locality
 * 
 * @return null or locality
 */
public String getLocality(Context context) {
    List<Address> addresses = getGeocoderAddress(context);
    if (addresses != null && addresses.size() > 0) {
        Address address = addresses.get(0);
        String locality = address.getLocality();

        return locality;
    } else {
        return null;
    }
}

/**
 * Try to get Postal Code
 * 
 * @return null or postalCode
 */
public String getPostalCode(Context context) {
    List<Address> addresses = getGeocoderAddress(context);
    if (addresses != null && addresses.size() > 0) {
        Address address = addresses.get(0);
        String postalCode = address.getPostalCode();

        return postalCode;
    } else {
        return null;
    }
}

/**
 * Try to get CountryName
 * 
 * @return null or postalCode
 */
public String getCountryName(Context context) {
    List<Address> addresses = getGeocoderAddress(context);
    if (addresses != null && addresses.size() > 0) {
        Address address = addresses.get(0);
        String countryName = address.getCountryName();

        return countryName;
    } else {
        return null;
    }
}

@Override
public void onLocationChanged(Location location) {
}

@Override
public void onProviderDisabled(String provider) {
}

@Override
public void onProviderEnabled(String provider) {
}

@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
}

@Override
public IBinder onBind(Intent intent) {
    return null;
}
}

回答by im-o

before get last location, maybe you want get current location, check if null or have. if not set last loccation if you want use FusedLocationProviderClient and before use it adding this:

在获取最后一个位置之前，也许您想获取当前位置，检查是否为空或有。如果没有设置最后一个位置，如果你想使用FusedLocationProviderClient并且在使用它之前添加这个：

implementation 'com.google.android.gms:play-services-location:16.0.0'

实现 'com.google.android.gms:play-services-location:16.0.0'

on your build.gradle(Module: app), and call method zoomMyCuurentLocation() whean activity create.

在您的 build.gradle(Module: app) 上，并在活动创建时调用方法 zoomMyCuurentLocation()。

private void zoomMyCuurentLocation() {
    LocationManager locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);
    Criteria criteria = new Criteria();
    if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
        ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION);
    }
    Location location = locationManager.getLastKnownLocation(locationManager.getBestProvider(criteria, false));
    if (location != null) {
        double lat = location.getLatitude();
        double longi = location.getLongitude();
        LatLng latLng = new LatLng(lat,longi);
        mMap.animateCamera(CameraUpdateFactory.newLatLngZoom(latLng, 14.f));
        Log.d(TAG, "zoomMyCuurentLocation: location not null");
    } else {
        setMyLastLocation();
    }
}

private void setMyLastLocation() {
    Log.d(TAG, "setMyLastLocation: excecute, and get last location");
    FusedLocationProviderClient fusedLocationClient = LocationServices.getFusedLocationProviderClient(this);
    if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
        return;
    }
    fusedLocationClient.getLastLocation().addOnSuccessListener(this, new OnSuccessListener<Location>() {
        @Override
        public void onSuccess(Location location) {
            if (location != null){
                double lat = location.getLatitude();
                double longi = location.getLongitude();
                LatLng latLng = new LatLng(lat,longi);
                Log.d(TAG, "MyLastLocation coordinat :"+latLng);
                mMap.animateCamera(CameraUpdateFactory.newLatLngZoom(latLng, 14.f));
            }
        }
    });
}

回答by Aman Kumar Gupta

To fetch the last location, you can refer to the above provided answers where you can use Location Manager or FusedLocationClient

要获取最后一个位置，您可以参考上面提供的答案，您可以在其中使用位置管理器或 FusedLocationClient

But You can also make use of LocationServiceswhich is faster than other approaches.

但是您也可以使用比其他方法更快的LocationServices。

So let me provide a brief working :

所以让我提供一个简短的工作：

1) Add these two dependencies in your gradle app file

1)在你的 gradle app 文件中添加这两个依赖

implementation 'com.google.android.gms:play-services-maps:17.0.0'
implementation 'com.google.android.gms:play-services-location:17.0.0'

2) Add these permissions in the manifest file outside applicationtag

2）在applicationtag外的manifest文件中添加这些权限

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

3) Declare variable outside onCreate

3)在 onCreate 之外声明变量

private FusedLocationProviderClient fusedLocationClient;

4) Now inside onCreate :

4)现在在 onCreate 里面：

fusedLocationClient = LocationServices.getFusedLocationProviderClient(this);
fetchLastLocation();

5) No define fetchLastLocation method

5)没有定义 fetchLastLocation 方法

private void fetchLastLocation() {

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            if (checkSelfPermission(Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && checkSelfPermission(Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
                // TODO: Consider calling
                //    Activity#requestPermissions
                // here to request the missing permissions, and then overriding
                //   public void onRequestPermissionsResult(int requestCode, String[] permissions,
                //                                          int[] grantResults)
                // to handle the case where the user grants the permission. See the documentation
                // for Activity#requestPermissions for more details.
//                    Toast.makeText(MainActivity.this, "Permission not granted, Kindly allow permission", Toast.LENGTH_LONG).show();
                showPermissionAlert();
                return;
            }
        }
        fusedLocationClient.getLastLocation()
                .addOnSuccessListener(this, new OnSuccessListener<Location>() {
                    @Override
                    public void onSuccess(Location location) {
                        // Got last known location. In some rare situations this can be null.
                        if (location != null) {
                            // Logic to handle location object
                            Log.e("LAST LOCATION: ", location.toString());
                        }
                    }
                });

    }

6) Now define other two method for permission request

6)现在定义另外两种权限请求方法

@Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        switch (requestCode) {
            case 123: {
                // If request is cancelled, the result arrays are empty.
                if (grantResults[0] == PackageManager.PERMISSION_DENIED) {
                    // permission was denied, show alert to explain permission
                    showPermissionAlert();
                }else{
                    //permission is granted now start a background service
                    if (ActivityCompat.checkSelfPermission(getApplicationContext(), Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED
                            && ActivityCompat.checkSelfPermission(getApplicationContext(), Manifest.permission.ACCESS_COARSE_LOCATION) == PackageManager.PERMISSION_GRANTED) {
                        fetchLastLocation();
                    }
                }
            }
        }
    }

    private void showPermissionAlert(){
        if (ActivityCompat.checkSelfPermission(MainHomeActivity.this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED
                && ActivityCompat.checkSelfPermission(MainHomeActivity.this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
            ActivityCompat.requestPermissions(MainHomeActivity.this, new String[]{Manifest.permission.ACCESS_COARSE_LOCATION, Manifest.permission.ACCESS_FINE_LOCATION}, 123);
        }
    }

Note: Replace context with your class context

注意：用你的类上下文替换上下文

You will get your location in Logcat.

您将在 Logcat 中获得您的位置。

Hope this will hope you or somebody else

希望这会希望你或其他人

回答by Gautam Pansheriya

            // Get the location from the given provider
            Location location = locationManager
                    .getLastKnownLocation(provider);

            locationManager.requestLocationUpdates(provider, 1000, 1, this);

回答by Mayur

Below is the way I am trying to get last location.

下面是我试图获得最后一个位置的方式。

private void setUpMap(){
    //Location location = mMap.getMyLocation();
    mMap.setMyLocationEnabled(true);
    //mMap.addMarker(new MarkerOptions().position(new LatLng(0, 0)).title("Marker"));
    mMap.setOnMyLocationChangeListener(new GoogleMap.OnMyLocationChangeListener() {
        @Override
        public void onMyLocationChange(Location location) {
             mMap.addMarker(new MarkerOptions().position(new LatLng(location.getLatitude(), location.getLongitude())).title("My Location"));
             mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(new LatLng(location.getLatitude(),location.getLongitude()),10));
             mMap.setOnMyLocationChangeListener(null);
        }
    });
}