java - GPS 可在除 Lollipop 之外的所有设备上使用

Question

很久以前，我编写了一个 Android 应用程序，它需要知道设备的位置。为了抽象对设备位置的访问，我编写了一个类来管理所有与位置相关的事物，存储当前设备的位置，并在 GPS 或互联网状态发生变化时调用主要 Activity 以通知用户。

此应用程序一直在所有设备上运行，直到我购买了附带 Lollipop 的 Samsung Galaxy A5 2016。它适用于我在旧版 Android 版本上测试过的所有 Jellybean 设备，但在 A5 2016 上，用户会收到 GPS 状态更改的通知，但 onLocationChanged() 方法一定不能工作，因为存储在此类中的位置始终为空。为什么这个用于获取位置的类一直在所有设备上工作，但现在在 Lollipop 上停止工作？真是令人沮丧。 Android 应用程序应该是向前兼容的。以下是管理位置的类的代码，该类已停止在 Lollipop 上工作。在 Lollipop 之前，位置通常存储在 Location 类型的类的实例属性上，但从 Lollipop 开始，位置不再存储。

package bembibre.personlocator.logic.locationservices;

import android.content.Context;
import android.location.GpsStatus;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.location.LocationProvider;
import android.os.Bundle;
import android.os.SystemClock;
import bembibre.personlocator.activities.MainActivity;
import bembibre.personlocator.logic.Action;
import bembibre.personlocator.logic.internet.InternetManager;

/**
 * Clase singleton que permite averiguar la localización del usuario en cada
 * momento.
 * 
 * @author misines
 *
 */
public class MyLocationManager {

    /**
     * Única instancia que puede existir de este objeto (es un singleton).
     */
    private static MyLocationManager instance = new MyLocationManager();

    private static int GPS_INTERVAL = 3000;

    /**
     * Actividad que llama a este objeto y que necesita conocer la localización
     * del usuario.
     */
    private MainActivity activity;

    /**
     * Objeto de Android que permite acceder a la localización del usuario.
     */
    private LocationManager locationManager;

    /**
     * Objeto que se encarga de escuchar cambios de localización basada en red.
     */
    private LocationListener networkLocationListener;

    /**
     * Objeto que se encarga de escuchar cambios de localización basada en GPS.
     */
    private LocationListener gpsLocationListener;

    private int networkStatus = LocationProvider.OUT_OF_SERVICE;

    private int gpsStatus = LocationProvider.OUT_OF_SERVICE;

    private EnumGpsStatuses status = EnumGpsStatuses.BAD;

    /**
     * Este atributo contiene la última localización del usuario determinada
     * por red (no muy exacta) o <code>null</code> si no se ha podido
     * determinar (por ejemplo porque no hay Internet).
     */
    private Location networkLocation;

    /**
     * Este atributo contiene la última localización del usuario determinada
     * por GPS (es más exacta que por red) o <code>null</code> si no se ha
     * podido determinar (por ejemplo porque no está activado el GPS).
     */
    private Location gpsLocation;
    private Long gpsLastLocationMillis;

    private boolean networkProviderEnabled = false;



    public static MyLocationManager getInstance() {
        return MyLocationManager.instance;
    }

    private void setNetworkLocation(Location location) {
        this.networkLocation = location;
    }

    private void setGpsLocation(Location location) {
        this.gpsLocation = location;
    }

    /**
     * Método que es llamado cuando el estado de alguno de los proveedores de
     * localización de los que depende esta clase ha cambiado de estado.
     */
    private void onStatusChanged() {
        switch(this.gpsStatus) {
        case LocationProvider.AVAILABLE:
            this.status = EnumGpsStatuses.GOOD;
            break;
        case LocationProvider.OUT_OF_SERVICE:
        case LocationProvider.TEMPORARILY_UNAVAILABLE:
        default:
            switch(this.networkStatus) {
            case LocationProvider.AVAILABLE:
                this.status = EnumGpsStatuses.SO_SO;
                break;
            case LocationProvider.OUT_OF_SERVICE:
            case LocationProvider.TEMPORARILY_UNAVAILABLE:
            default:
                this.status = EnumGpsStatuses.BAD;
            }
        }

        if (this.activity != null) {
            this.activity.onGpsStatusChanged(this.status);
        }
    }

    private void setNetworkStatus(int status) {
        this.networkStatus = status;
        this.onStatusChanged();
    }

    private void setGpsStatus(int status) {
        this.gpsStatus = status;
        this.onStatusChanged();
    }

    private class MyGPSListener implements GpsStatus.Listener {
        public void onGpsStatusChanged(int event) {
            boolean isGPSFix;
            switch (event) {
                case GpsStatus.GPS_EVENT_SATELLITE_STATUS:
                    if (MyLocationManager.this.gpsLastLocationMillis != null) {
                        isGPSFix = (SystemClock.elapsedRealtime() - MyLocationManager.this.gpsLastLocationMillis) < 3 * MyLocationManager.GPS_INTERVAL;
                    } else {
                        isGPSFix = false;
                    }

                    if (isGPSFix) { // A fix has been acquired.
                        MyLocationManager.this.setGpsStatus(LocationProvider.AVAILABLE);
                    } else { // The fix has been lost.
                        MyLocationManager.this.setGpsStatus(LocationProvider.OUT_OF_SERVICE);
                    }

                    break;
                case GpsStatus.GPS_EVENT_FIRST_FIX:
                    // Do something.
                    MyLocationManager.this.setGpsStatus(LocationProvider.AVAILABLE);

                    break;
            }
        }
    }

    /**
     * Inicializa este objeto para que empiece a funcionar y trate de
     * determinar la localización del dispositivo. Además inicializa al
     * <code>InternetManager</code>, de modo que una vez que se haya llamado a
     * este método, InternetManager estará disponible en todo momento para ver
     * si la conexión a Internet funciona o hacer pruebas a dicha conexión.
     * 
     * @param activity
     */
    public void start(final MainActivity activity) {
        this.activity = activity;

        // Acquire a reference to the system Location Manager
        this.locationManager = (LocationManager) this.activity.getSystemService(Context.LOCATION_SERVICE);

        // Define a listener that responds to location updates
        this.networkLocationListener = new LocationListener() {
            public void onLocationChanged(Location location) {
                // Called when a new location is found by the network location
                // provider.
                MyLocationManager.this.setNetworkLocation(location);
                MyLocationManager.this.networkProviderEnabled = true;
                InternetManager.getInstance().makeInternetTest(activity);
            }

            public void onStatusChanged(String provider, int status, Bundle extras) {
                MyLocationManager.this.setNetworkStatus(status);
            }

            public void onProviderEnabled(String provider) {
                MyLocationManager.this.networkProviderEnabled = true;
                InternetManager.getInstance().makeInternetTest(activity);
            }

            public void onProviderDisabled(String provider) {
                MyLocationManager.this.networkProviderEnabled = false;
                MyLocationManager.this.setNetworkStatus(LocationProvider.OUT_OF_SERVICE);
            }
        };

        this.gpsLocationListener = new LocationListener() {
            public void onLocationChanged(Location location) {
                // Called when a new location is found by the network location
                // provider.
                MyLocationManager.this.setGpsLocation(location);
                MyLocationManager.this.gpsLastLocationMillis = SystemClock.elapsedRealtime();
                //MyLocationManager.this.setGpsStatus(LocationProvider.AVAILABLE);
            }

            public void onStatusChanged(String provider, int status, Bundle extras) {
                MyLocationManager.this.setGpsStatus(status);
            }

            public void onProviderEnabled(String provider) {

            }

            public void onProviderDisabled(String provider) {
                MyLocationManager.this.setGpsStatus(LocationProvider.OUT_OF_SERVICE);
            }
        };

        // Register the listener with the Location Manager to receive location
        // updates
        try {
            this.locationManager.requestLocationUpdates(
                LocationManager.NETWORK_PROVIDER, 3000, 0, this.networkLocationListener
            );

            this.locationManager.requestLocationUpdates(
                LocationManager.GPS_PROVIDER, GPS_INTERVAL, 0, this.gpsLocationListener
            );
        } catch (Exception e) {
            e.printStackTrace();
        }

        this.locationManager.addGpsStatusListener(new MyGPSListener());



        /*
         * Hay que inicializar al InternetManager y decirle que avise a este
         * objeto cada vez que el Internet vuelva o se pierda. Para ello usamos
         * dos objetos Action.
         */
        Action action1 = new Action() {

            @Override
            public void execute(String string) {
                MyLocationManager.getInstance().internetHasBeenRecovered();
            }

        };
        Action action2 = new Action() {

            @Override
            public void execute(String string) {
                MyLocationManager.getInstance().internetHasBeenLost();
            }

        };
        InternetManager.getInstance().initialize(activity, action1, action2);
    }

    public void stop() {
        if (this.locationManager != null) {
            if (this.networkLocationListener != null) {
                this.locationManager.removeUpdates(this.networkLocationListener);
            }
            if (this.gpsLocationListener != null) {
                this.locationManager.removeUpdates(this.gpsLocationListener);
            }
        }

        this.activity = null;
    }

    /**
     * Devuelve la última localización conocida basada en red o
     * <code>null</code> si no hay.
     * 
     * @return la última localización conocida basada en red o
     * <code>null</code> si no hay.
     */
    public Location getNetworkLocation() {
        Location result;

        if (this.networkLocation == null) {
            result = this.gpsLocation;
        } else {
            result = this.networkLocation;
        }

        return result;
    }

    /**
     * Si el gps está disponible y tenemos una posición guaradada basada en GPS
     * entonces la devuelve. En caso contrario intenta devolver la última
     * localización basada en red, y si tampoco está disponible, devuelve
     * <code>null</code>.
     * 
     * @return la localización más precisa que esté disponible en este momento.
     */
    public Location getFinestLocationAvailable() {
        Location result;

        switch(this.gpsStatus) {
        case LocationProvider.AVAILABLE:
            if (this.gpsLocation == null) {
                result = this.networkLocation;
            } else {
                result = this.gpsLocation;
            }
        case LocationProvider.TEMPORARILY_UNAVAILABLE:
        case LocationProvider.OUT_OF_SERVICE:
        default:
            result = this.networkLocation;
        }

        return result;
    }

    /**
     * Devuelve el estado actual del GPS.
     * 
     * @return el estado actual del GPS.
     */
    public EnumGpsStatuses getStatus() {
        return this.status;
    }

    /**
     * Método al que tenemos que llamar siempre que nos enteremos de que
     * tenemos Internet, para que se sepa que la localización por red funciona.
     */
    public void internetHasBeenRecovered() {
        if (this.networkProviderEnabled) {
            this.setNetworkStatus(LocationProvider.AVAILABLE);
        } else {
            this.setNetworkStatus(LocationProvider.OUT_OF_SERVICE);
        }
        this.onStatusChanged();
    }

    /**
     * Método al que tenemos que llamar siempre que nos enteremos de que la
     * conexión a Internet se ha perdido, para que este objeto se dé cuenta de
     * que el servicio de localización por red ya no funciona.
     */
    public void internetHasBeenLost() {
        this.setNetworkStatus(LocationProvider.OUT_OF_SERVICE);
        this.onStatusChanged();
    }
}

Answer 1

尝试使用以下代码:

public class MyLocationService extends Service{

    Location mLastLocation;
    android.location.LocationListener mLocationListener;
    LocationManager locationManager;

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        super.onStartCommand(intent, flags, startId);

        // Acquire a reference to the system Location Manager
        locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);

        // Define a listener that responds to location updates
        mLocationListener = new android.location.LocationListener() {
            @Override
            public void onLocationChanged(Location location) {
                // Called when a new location is found by the gps location provider.

                mLastLocation = location; // this is the object you need to play with Location changes

                // do stuffs here you want after location changes
            }

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

            @Override
            public void onProviderEnabled(String provider) {}

            @Override
            public void onProviderDisabled(String provider) {}
        };

        String locationProvider = LocationManager.GPS_PROVIDER; // here, you can also set Network provider as per your need

        // Register the listener with the Location Manager to receive location updates
        try{
            locationManager.requestLocationUpdates(locationProvider, 5000, 0, mLocationListener);
            mLastLocation = locationManager.getLastKnownLocation(locationProvider);
        } catch (SecurityException e){
            e.printStackTrace();
        }

        return START_STICKY;
    }
}

Manifest 权限要求您已经知道:

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

最后，您的服务应在 list 中声明，如下所示:

<service android:name=".service.MyLocationService" />

您必须从 Activity 或 Application 类启动服务。