Android上的LocationManager API似乎对一个只需要偶尔粗略估计用户位置的应用程序来说有点麻烦。

我正在开发的应用程序本身并不是一个定位应用程序,但它确实需要获取用户的位置,以便显示附近企业的列表。它不需要担心用户是否在移动或类似的事情。

以下是我想做的:

向用户显示附近位置的列表。预加载用户的位置,以便在“活动X”中需要它时,它将可用。我并不特别关心更新的准确性或频率。只要不太远,只要抓住一个位置就足够了。也许如果我想变得更漂亮,我会每隔几分钟左右更新一次位置,但这不是一个很大的优先事项。适用于任何具有GPS或网络位置提供商的设备。

这似乎并不难,但在我看来,我必须组建两个不同的位置提供商(GPS和NETWORK),并管理每个提供商的生命周期。不仅如此,我还必须在多个活动中复制相同的代码以满足#2。过去,我曾尝试使用getBestProvider()将解决方案简化为仅使用一个位置提供程序,但这似乎只提供了最好的“理论”提供程序,而不是实际会为您提供最佳结果的提供程序。

有没有更简单的方法来实现这一点?


当前回答

在android系统中获取位置更新需要很多东西,需要大量的bolierplate代码。

你需要照顾好

Google Play服务可用性检查,更新Google play服务,如果它是旧的或不可用GoogleApiClient的对话框创建及其连接、断开等回调。停止并释放用于位置更新的资源处理位置权限方案检查位置服务是否打开或关闭获取最新位置也不是那么容易如果在一定时间后未找到位置,则回退到最后一个已知位置

我已经创建了Android EasyLocation(小型Android库),它将处理所有这些事情,您可以专注于业务逻辑。

您只需要扩展EasyLocationActivity

requestSingleLocationFix(easyLocationRequest);

or

requestLocationUpdates(easyLocationRequest);

点击此处查看示例应用程序和所需步骤https://github.com/akhgupta/Android-EasyLocation

其他回答

使用以下代码,它将提供可用的最佳提供商:

String locCtx = Context.LOCATION_SERVICE; 

LocationManager locationMgr = (LocationManager) ctx.getSystemService(locCtx);

Criteria criteria  = new Criteria();
criteria.setAccuracy(Criteria.ACCURACY_FINE);
criteria.setAltitudeRequired(false);
criteria.setBearingRequired(false);
criteria.setCostAllowed(true);
criteria.setPowerRequirement(Criteria.POWER_LOW);

String provider = locationMgr.getBestProvider(criteria, true);

System.out.println("Best Available provider::::"+provider);

实际上,我们可以使用两个提供商(GPS和网络)。他们只是分享一个公共听众:

locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 10 * 1000, (float) 10.0, listener);
locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 90 * 1000, (float) 10.0, listener);

这是必要的,因为总是需要及时调用OnLocationChanged()方法。

这是提供用户当前位置的代码

创建地图活动:

public class Maps extends MapActivity {

    public static final String TAG = "MapActivity";
    private MapView mapView;
    private LocationManager locationManager;
    Geocoder geocoder;
    Location location;
    LocationListener locationListener;
    CountDownTimer locationtimer;
    MapController mapController;
    MapOverlay mapOverlay = new MapOverlay();

    @Override
    protected void onCreate(Bundle icicle) {
        super.onCreate(icicle);
        setContentView(R.layout.main);
        initComponents();
        mapView.setBuiltInZoomControls(true);
        mapView.setSatellite(true);
        mapView.setTraffic(true);
        mapView.setStreetView(true);
        mapController = mapView.getController();
        mapController.setZoom(16);
        locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);
        if (locationManager == null) {
            Toast.makeText(Maps.this, "Location Manager Not Available",
                Toast.LENGTH_SHORT).show();
            return;
        }
        location = locationManager
                .getLastKnownLocation(LocationManager.GPS_PROVIDER);
        if (location == null)
            location = locationManager
                    .getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
        if (location != null) {
            double lat = location.getLatitude();
            double lng = location.getLongitude();
            Toast.makeText(Maps.this, "Location Are" + lat + ":" + lng,
                Toast.LENGTH_SHORT).show();
            GeoPoint point = new GeoPoint((int) (lat * 1E6), (int) (lng * 1E6));
            mapController.animateTo(point, new Message());
            mapOverlay.setPointToDraw(point);
            List<Overlay> listOfOverlays = mapView.getOverlays();
            listOfOverlays.clear();
            listOfOverlays.add(mapOverlay);
        }
        locationListener = new LocationListener() {

            public void onStatusChanged(String arg0, int arg1, Bundle arg2) {}

            public void onProviderEnabled(String arg0) {}

            public void onProviderDisabled(String arg0) {}

            public void onLocationChanged(Location l) {
                location = l;
                locationManager.removeUpdates(this);
                if (l.getLatitude() == 0 || l.getLongitude() == 0) {
                } else {
                    double lat = l.getLatitude();
                    double lng = l.getLongitude();
                    Toast.makeText(Maps.this, "Location Are" + lat + ":" + lng,
                        Toast.LENGTH_SHORT).show();
                }
            }
        };
        if (locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER))
            locationManager.requestLocationUpdates(
                LocationManager.GPS_PROVIDER, 1000, 10f, locationListener);
        locationManager.requestLocationUpdates(
            LocationManager.NETWORK_PROVIDER, 1000, 10f, locationListener);
        locationtimer = new CountDownTimer(30000, 5000) {

            @Override
            public void onTick(long millisUntilFinished) {
                if (location != null) locationtimer.cancel();
            }

            @Override
            public void onFinish() {
                if (location == null) {
                }
            }
        };
        locationtimer.start();
    }

    public MapView getMapView() {
        return this.mapView;
    }

    private void initComponents() {
        mapView = (MapView) findViewById(R.id.map_container);
        ImageView ivhome = (ImageView) this.findViewById(R.id.imageView_home);
        ivhome.setOnClickListener(new OnClickListener() {

            public void onClick(View arg0) {
                // TODO Auto-generated method stub
                Intent intent = new Intent(Maps.this, GridViewContainer.class);
                startActivity(intent);
                finish();
            }
        });
    }

    @Override
    protected boolean isRouteDisplayed() {
        return false;
    }

    class MapOverlay extends Overlay {

        private GeoPoint pointToDraw;

        public void setPointToDraw(GeoPoint point) {
            pointToDraw = point;
        }

        public GeoPoint getPointToDraw() {
            return pointToDraw;
        }

        @Override
        public boolean draw(Canvas canvas, MapView mapView, boolean shadow,
                long when) {
            super.draw(canvas, mapView, shadow);
            Point screenPts = new Point();
            mapView.getProjection().toPixels(pointToDraw, screenPts);
            Bitmap bmp = BitmapFactory.decodeResource(getResources(),
                R.drawable.select_map);
            canvas.drawBitmap(bmp, screenPts.x, screenPts.y - 24, null);
            return true;
        }
    }
}

main.xml:

    <?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@android:color/black"
        android:orientation="vertical" >

        <com.google.android.maps.MapView
            android:id="@+id/map_container"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:apiKey="yor api key"
            android:clickable="true"
            android:focusable="true" />

    </LinearLayout>

并在清单中定义以下权限:

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

我已经创建了一个小应用程序,并逐步描述以获取当前位置GPS坐标。

以下URL中的完整示例源代码:


获取当前位置坐标,城市名称-在Android中


查看其工作原理:

我们只需要在清单文件中添加此权限<uses permission android:name=“android.permission.ACCESS_FINE_LOCATION”></使用权限>并像这样创建LocationManager实例LocationManager LocationManager=(LocationManager)getSystemService(Context.LOCATION_SERVICE);检查GPS是否已启用然后实现LocationListener和Get CoordinatesLocationListener LocationListener=新的MyLocationListeners();locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER,5000,10,locationListener);下面是要做的示例代码


/*----------Listener class to get coordinates ------------- */
private class MyLocationListener implements LocationListener {

    @Override
    public void onLocationChanged(Location loc) {
        editLocation.setText("");
        pb.setVisibility(View.INVISIBLE);
        Toast.makeText(
            getBaseContext(),
            "Location changed: Lat: " + loc.getLatitude() + " Lng: "
                + loc.getLongitude(), Toast.LENGTH_SHORT).show();
        String longitude = "Longitude: " + loc.getLongitude();
        Log.v(TAG, longitude);
        String latitude = "Latitude: " + loc.getLatitude();
        Log.v(TAG, latitude);
        /*-------to get City-Name from coordinates -------- */
        String cityName = null;
        Geocoder gcd = new Geocoder(getBaseContext(), Locale.getDefault());
        List<Address> addresses;
        try {
            addresses = gcd.getFromLocation(loc.getLatitude(),
                loc.getLongitude(), 1);
            if (addresses.size() > 0)
                System.out.println(addresses.get(0).getLocality());
            cityName = addresses.get(0).getLocality();
        } catch (IOException e) {
            e.printStackTrace();
        }
        String s = longitude + "\n" + latitude + "\n\nMy Current City is: "
            + cityName;
        editLocation.setText(s);
    }

    @Override
    public void onProviderDisabled(String provider) {}

    @Override
    public void onProviderEnabled(String provider) {}

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

以下是我所做的:

首先,我检查启用了哪些提供程序。有些可能在设备上禁用,有些可能在应用程序清单中禁用。如果有任何提供程序可用,我将启动位置侦听器和超时计时器。在我的例子中,这是20秒,可能不够GPS,所以你可以放大它。如果我从位置侦听器获取更新,我将使用提供的值。我停止听众和计时器。如果我没有得到任何更新和计时器,我必须使用最近的已知值。我从可用的提供程序中获取最新的已知值,并选择其中最新的值。

以下是我如何使用我的课程:

LocationResult locationResult = new LocationResult(){
    @Override
    public void gotLocation(Location location){
        //Got the location!
    }
};
MyLocation myLocation = new MyLocation();
myLocation.getLocation(this, locationResult);

这里是MyLocation类:

import java.util.Timer;
import java.util.TimerTask;
import android.content.Context;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;

public class MyLocation {
    Timer timer1;
    LocationManager lm;
    LocationResult locationResult;
    boolean gps_enabled=false;
    boolean network_enabled=false;

    public boolean getLocation(Context context, LocationResult result)
    {
        //I use LocationResult callback class to pass location value from MyLocation to user code.
        locationResult=result;
        if(lm==null)
            lm = (LocationManager) context.getSystemService(Context.LOCATION_SERVICE);

        //exceptions will be thrown if provider is not permitted.
        try{gps_enabled=lm.isProviderEnabled(LocationManager.GPS_PROVIDER);}catch(Exception ex){}
        try{network_enabled=lm.isProviderEnabled(LocationManager.NETWORK_PROVIDER);}catch(Exception ex){}

        //don't start listeners if no provider is enabled
        if(!gps_enabled && !network_enabled)
            return false;

        if(gps_enabled)
            lm.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, locationListenerGps);
        if(network_enabled)
            lm.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 0, 0, locationListenerNetwork);
        timer1=new Timer();
        timer1.schedule(new GetLastLocation(), 20000);
        return true;
    }

    LocationListener locationListenerGps = new LocationListener() {
        public void onLocationChanged(Location location) {
            timer1.cancel();
            locationResult.gotLocation(location);
            lm.removeUpdates(this);
            lm.removeUpdates(locationListenerNetwork);
        }
        public void onProviderDisabled(String provider) {}
        public void onProviderEnabled(String provider) {}
        public void onStatusChanged(String provider, int status, Bundle extras) {}
    };

    LocationListener locationListenerNetwork = new LocationListener() {
        public void onLocationChanged(Location location) {
            timer1.cancel();
            locationResult.gotLocation(location);
            lm.removeUpdates(this);
            lm.removeUpdates(locationListenerGps);
        }
        public void onProviderDisabled(String provider) {}
        public void onProviderEnabled(String provider) {}
        public void onStatusChanged(String provider, int status, Bundle extras) {}
    };

    class GetLastLocation extends TimerTask {
        @Override
        public void run() {
             lm.removeUpdates(locationListenerGps);
             lm.removeUpdates(locationListenerNetwork);

             Location net_loc=null, gps_loc=null;
             if(gps_enabled)
                 gps_loc=lm.getLastKnownLocation(LocationManager.GPS_PROVIDER);
             if(network_enabled)
                 net_loc=lm.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);

             //if there are both values use the latest one
             if(gps_loc!=null && net_loc!=null){
                 if(gps_loc.getTime()>net_loc.getTime())
                     locationResult.gotLocation(gps_loc);
                 else
                     locationResult.gotLocation(net_loc);
                 return;
             }

             if(gps_loc!=null){
                 locationResult.gotLocation(gps_loc);
                 return;
             }
             if(net_loc!=null){
                 locationResult.gotLocation(net_loc);
                 return;
             }
             locationResult.gotLocation(null);
        }
    }

    public static abstract class LocationResult{
        public abstract void gotLocation(Location location);
    }
}

可能有人也想修改我的逻辑。例如,如果您从网络提供商获得更新,不要停止侦听器,而是继续等待。GPS提供了更准确的数据,所以值得等待。如果计时器过去了,并且您从网络获得了更新,而不是GPS,那么您可以使用网络提供的值。

还有一种方法是使用LocationClienthttp://developer.android.com/training/location/retrieve-current.html.但它需要在用户设备上安装Google Play Services apk。