如何在Android中获取位置管理器的最后已知位置？

Question

如何在Android中获取位置管理器的最后已知位置？

17

我正在使用简单的位置管理器对象来获取设备的lastKnownLocation()，但是返回null对象，有人能告诉我为什么吗？

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

 }

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" />

那么有没有遗漏的设置吗？我已经检查了设备中的位置服务是开启的请给出一些可工作示例的链接

- Aditi K

2

请遵循最新的文档 http://developer.android.com/training/location/retrieve-current.html#GetLocation :) - Deniz

请查看此链接：http://stackoverflow.com/a/15997304/3020568 - Deniz

@deniz 谢谢，我正在实现您给出的第一个链接。这里获取到的lastLocation是null值。以下是代码：if (mUpdatesRequested) {mLocationClient.requestLocationUpdates(mLocationRequest, this);} - Aditi K

是的，我正在尝试，但仍然没有得到 :( - Aditi K

在OnCreate中，将“getLocation();”更改为“Location theLoc = getLocation();”如果您不将其分配给对象，则返回值毫无意义。 - toto_tata

显示剩余5条评论

9个回答

4

关于这个问题，可能会有一个笨拙的答案……我重新启动了设备之后，问题得到了解决。请确保您的位置服务已启用并正常工作。

- Aditi K

3

我用来获取地点名称的位置信息工具是：

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

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 :
 * https://dev59.com/1XRB5IYBdhLWcg3w6LR2
 * -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;
}
}

- Archit Jain

1

我将使用GooglePlayLocation服务代替GPS。 - Aditi K

它正在运行一个用于获取位置的服务。提问者从未提到过特定间隔的位置报告。不适合所提出的问题。 - Abhinav Arora

3

我发现的最佳方法：

private Location getLastKnownLocation() {
    if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED || ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
        return null;
    }

    List<String> providers = locationManager.getProviders(true);
    Location bestLocation = null;
    for (String provider : providers) {
        Location l = locationManager.getLastKnownLocation(provider);
        if (l == null) {
            continue;
        }
        if (bestLocation == null || l.getAccuracy() < bestLocation.getAccuracy()) {
            // Found best last known location:
            bestLocation = l;
        }
    }

    return bestLocation;
}

locationManager变量可以通过系统服务LOCATION获得。

- larsaars

缺失：在List<String> providers之前，需要添加以下代码：LocationManager locationManager = (LocationManager) this.getSystemService(Context.LOCATION_SERVICE); - Luke Dupin

3

要获取最后一次位置，可以参考上面提供的答案，使用Location Manager或FusedLocationClient。

但您也可以使用比其他方法更快的LocationServices。

因此，让我简要介绍一下如何操作：

1）在gradle app文件中添加这两个依赖项

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

2）将这些权限添加到manifest文件的application标签外部

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

3) 在onCreate外声明变量

private FusedLocationProviderClient fusedLocationClient;

4) 现在在 onCreate 方法中添加：

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

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) 现在定义另外两个方法以请求权限

@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);
        }
    }

注意: 用你的类上下文替换context

你将在Logcat中获得你的位置。

希望这对你或其他人有所帮助。

- Aman Kumar Gupta

2

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

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

- Gautam Pansheriya

1

在 Kotlin 中解决问题：抱歉排版很糟糕。

Add these two dependencies in your gradle app file

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

Add these permissions in the manifest file outside applicationtag

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

Declare variable outside onCreate

 private lateinit var fusedLocationClient: FusedLocationProviderClient

Now inside onCreate :

 fusedLocationClient= LocationServices.getFusedLocationProviderClient(this)

 getCurrentLocation()

No define fetchLastLocation method Note:Here getCurrentLocation means the last location.

 private fun getCurrentLocation(){
 if(checkPermissions())
 {
     if(isLocationEnabled()){
         //final latitude and longitude
         if (ActivityCompat.checkSelfPermission(
                 this,
                 Manifest.permission.ACCESS_FINE_LOCATION
             ) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(
                 this,
                 Manifest.permission.ACCESS_COARSE_LOCATION
             ) != PackageManager.PERMISSION_GRANTED
         ) {
             requestPermission()
             return
         }
         // fusedLocationClient.getCurrentLocation()
         fusedLocationClient.lastLocation.addOnCompleteListener(this){ task->
             val location:Location?=task.result
             if(location==null)
             {
                 Toast.makeText(this,"NULL Received",Toast.LENGTH_SHORT).show()
             }
             else{
                 Toast.makeText(this,"Location SUCCESS",Toast.LENGTH_SHORT).show()
                 val geocoder = Geocoder(this, Locale.getDefault())
                 val addresses: MutableList<android.location.Address>? = geocoder.getFromLocation(location.latitude, location.longitude, 1)
                 cityName = addresses!![0].locality
                 startActivity(intent)
             }
         }
     }
     else
     {
         Toast.makeText(this,"Turn on location",Toast.LENGTH_SHORT).show()
         val intent= Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS)
         startActivity(intent)
     }
 }
 else
 {
     //request permission here
     requestPermission()
 }

}

Now define other methods for permission request

 private fun requestPermission() {
 ActivityCompat.requestPermissions(this, arrayOf(android.Manifest.permission.ACCESS_COARSE_LOCATION,android.Manifest.permission.ACCESS_FINE_LOCATION),
     PERMISSION_REQUEST_ACCESS_LOCATION)
 }

 companion object{
 private const val PERMISSION_REQUEST_ACCESS_LOCATION=100
 }

 private fun checkPermissions():Boolean {
 if (ActivityCompat.checkSelfPermission(
         this,
         android.Manifest.permission.ACCESS_FINE_LOCATION
     ) == PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(
         this,
         android.Manifest.permission.ACCESS_COARSE_LOCATION
     ) == PackageManager.PERMISSION_GRANTED
 ) {
     return true
 }
 return false
 }

 override fun onRequestPermissionsResult(
 requestCode: Int,
 permissions: Array<out String>,
 grantResults: IntArray
 ) {
 super.onRequestPermissionsResult(requestCode, permissions, grantResults)
 if(requestCode== PERMISSION_REQUEST_ACCESS_LOCATION)
 {
     if(grantResults.isNotEmpty() && grantResults[0]==PackageManager.PERMISSION_GRANTED){
         Toast.makeText(applicationContext,"Granted",Toast.LENGTH_SHORT).show()
         getCurrentLocation()
     }
     else{
         Toast.makeText(applicationContext,"DENIED",Toast.LENGTH_SHORT).show()
     }
 }
 }

 private fun isLocationEnabled():Boolean{
 val locationManager:LocationManager=getSystemService(Context.LOCATION_SERVICE) as LocationManager
 return locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER)||locationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER)
 }

- sahil333

1

以下是我尝试获取最后位置的方法。

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);
        }
    });
}

- Mayur

0

这里有一个更好的解决方案：

@Nullable
public static Location getLastKnownLocation(Context context, LocationManager locationManager) {
    if (ActivityCompat.checkSelfPermission(context, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED ||
            ActivityCompat.checkSelfPermission(context, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
        return null;
    }

    Criteria criteria = new Criteria();
    criteria.setAccuracy(Criteria.ACCURACY_FINE);

    String provider = locationManager.getBestProvider(criteria, true);
    if (provider == null) return null;

    return locationManager.getLastKnownLocation(provider);
}

这一行代码：criteria.setAccuracy(Criteria.ACCURACY_FINE); 就可以达到效果。

- Homayoon Ahmadi

网页内容由stack overflow 提供, 点击上面的

可以查看英文原文，
原文链接

- rivaldy · Accepted Answer

在获取最后位置之前，您可能需要获取当前位置，检查是否为空或已有位置。如果不为空，则设置最后位置，如果要使用FusedLocationProviderClient，则在使用它之前添加以下内容:

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

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

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));
            }
        }
    });
}