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
Kotlin版本的@Fedor Greate回答：
类的用法：
val locationResult = object : MyLocation.LocationResult() {
override fun gotLocation(location: Location?) {
val lat = location!!.latitude
val lon = location.longitude
Toast.makeText(context, "$lat --SLocRes-- $lon", Toast.LENGTH_SHORT).show()
}
}
val myLocation = MyLocation()
myLocation.getLocation(inflater.context, locationResult)
MyLocation类：
class MyLocation {
internal lateinit var timer1: Timer
internal var lm: LocationManager? = null
internal lateinit var locationResult: LocationResult
internal var gps_enabled = false
internal var network_enabled = false
internal var locationListenerGps: LocationListener = object : LocationListener {
override fun onLocationChanged(location: Location) {
timer1.cancel()
locationResult.gotLocation(location)
lm!!.removeUpdates(this)
lm!!.removeUpdates(locationListenerNetwork)
}
override fun onProviderDisabled(provider: String) {}
override fun onProviderEnabled(provider: String) {}
override fun onStatusChanged(provider: String, status: Int, extras: Bundle) {}
}
internal var locationListenerNetwork: LocationListener = object : LocationListener {
override fun onLocationChanged(location: Location) {
timer1.cancel()
locationResult.gotLocation(location)
lm!!.removeUpdates(this)
lm!!.removeUpdates(locationListenerGps)
}
override fun onProviderDisabled(provider: String) {}
override fun onProviderEnabled(provider: String) {}
override fun onStatusChanged(provider: String, status: Int, extras: Bundle) {}
}
fun getLocation(context: Context, result: LocationResult): Boolean {
//I use LocationResult callback class to pass location value from MyLocation to user code.
locationResult = result
if (lm == null)
lm = context.getSystemService(Context.LOCATION_SERVICE) as LocationManager?
//exceptions will be thrown if provider is not permitted.
try {
gps_enabled = lm!!.isProviderEnabled(LocationManager.GPS_PROVIDER)
} catch (ex: Exception) {
}
try {
network_enabled = lm!!.isProviderEnabled(LocationManager.NETWORK_PROVIDER)
} catch (ex: Exception) {
}
//don't start listeners if no provider is enabled
if (!gps_enabled && !network_enabled)
return false
if (ActivityCompat.checkSelfPermission(context,
Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED ||
ActivityCompat.checkSelfPermission(context, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) run {
ActivityCompat.requestPermissions(context as Activity,
arrayOf(Manifest.permission.ACCESS_FINE_LOCATION, Manifest.permission.ACCESS_COARSE_LOCATION), 111)
}
if (gps_enabled)
lm!!.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0f, locationListenerGps)
if (network_enabled)
lm!!.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 0, 0f, locationListenerNetwork)
timer1 = Timer()
timer1.schedule(GetLastLocation(context), 20000)
return true
}
internal inner class GetLastLocation(var context: Context) : TimerTask() {
override fun run() {
lm!!.removeUpdates(locationListenerGps)
lm!!.removeUpdates(locationListenerNetwork)
var net_loc: Location? = null
var gps_loc: Location? = null
if (ActivityCompat.checkSelfPermission(context,
Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED ||
ActivityCompat.checkSelfPermission(context, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED
) run {
ActivityCompat.requestPermissions(context as Activity,
arrayOf(Manifest.permission.ACCESS_FINE_LOCATION, Manifest.permission.ACCESS_COARSE_LOCATION),111)
}
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)
}
}
abstract class LocationResult {
abstract fun gotLocation(location: Location?)
}
}
其他回答
地理定位的简单和最佳方式。
LocationManager lm = null;
boolean network_enabled;
if (lm == null)
lm = (LocationManager) Kikit.this.getSystemService(Context.LOCATION_SERVICE);
network_enabled = lm.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
dialog = ProgressDialog.show(Kikit.this, "", "Fetching location...", true);
final Handler handler = new Handler();
timer = new Timer();
TimerTask doAsynchronousTask = new TimerTask() {
@Override
public void run() {
handler.post(new Runnable() {
@Override
public void run()
{
Log.e("counter value","value "+counter);
if(counter<=8)
{
try
{
counter++;
if (network_enabled) {
lm = (LocationManager) Kikit.this.getSystemService(Context.LOCATION_SERVICE);
Log.e("in network_enabled..","in network_enabled");
// Define a listener that responds to location updates
LocationListener locationListener = new LocationListener()
{
public void onLocationChanged(Location location)
{
if(attempt == false)
{
attempt = true;
Log.e("in location listener..","in location listener..");
longi = location.getLongitude();
lati = location.getLatitude();
Data.longi = "" + longi;
Data.lati = "" + lati;
Log.e("longitude : ",""+longi);
Log.e("latitude : ",""+lati);
if(faceboo_name.equals(""))
{
if(dialog!=null){
dialog.cancel();}
timer.cancel();
timer.purge();
Data.homepage_resume = true;
lm = null;
Intent intent = new Intent();
intent.setClass(Kikit.this,MainActivity.class);
startActivity(intent);
finish();
}
else
{
isInternetPresent = cd.isConnectingToInternet();
if (isInternetPresent)
{
if(dialog!=null)
dialog.cancel();
Showdata();
}
else
{
error_view.setText(Data.internet_error_msg);
error_view.setVisibility(0);
error_gone();
}
}
}
}
public void onStatusChanged(String provider, int status,
Bundle extras) {
}
public void onProviderEnabled(String provider) {
//Toast.makeText(getApplicationContext(), "Location enabled", Toast.LENGTH_LONG).show();
}
public void onProviderDisabled(String provider) {
}
};
// Register the listener with the Location Manager to receive
// location updates
lm.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 100000, 10,locationListener);
} else{
//Toast.makeText(getApplicationContext(), "No Internet Connection.", 2000).show();
buildAlertMessageNoGps();
}
} catch (Exception e) {
// TODO
// Auto-generated
// catch
// block
}
}
else
{
timer.purge();
timer.cancel();
if(attempt == false)
{
attempt = true;
String locationProvider = LocationManager.NETWORK_PROVIDER;
// Or use LocationManager.GPS_PROVIDER
try {
Location lastKnownLocation = lm.getLastKnownLocation(locationProvider);
longi = lastKnownLocation.getLongitude();
lati = lastKnownLocation.getLatitude();
Data.longi = "" + longi;
Data.lati = "" + lati;
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
Log.i("exception in loc fetch", e.toString());
}
Log.e("longitude of last known location : ",""+longi);
Log.e("latitude of last known location : ",""+lati);
if(Data.fb_access_token == "")
{
if(dialog!=null){
dialog.cancel();}
timer.cancel();
timer.purge();
Data.homepage_resume = true;
Intent intent = new Intent();
intent.setClass(Kikit.this,MainActivity.class);
startActivity(intent);
finish();
}
else
{
isInternetPresent = cd.isConnectingToInternet();
if (isInternetPresent)
{
if(dialog!=null){
dialog.cancel();}
Showdata();
}
else
{
error_view.setText(Data.internet_error_msg);
error_view.setVisibility(0);
error_gone();
}
}
}
}
}
});
}
};
timer.schedule(doAsynchronousTask, 0, 2000);
private void buildAlertMessageNoGps() {
final AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setMessage("Your WiFi & mobile network location is disabled , do you want to enable it?")
.setCancelable(false)
.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
public void onClick(@SuppressWarnings("unused") final DialogInterface dialog, @SuppressWarnings("unused") final int id)
{
startActivity(new Intent(android.provider.Settings.ACTION_LOCATION_SOURCE_SETTINGS));
setting_page = true;
}
})
.setNegativeButton("No", new DialogInterface.OnClickListener() {
public void onClick(final DialogInterface dialog, @SuppressWarnings("unused") final int id) {
dialog.cancel();
finish();
}
});
final AlertDialog alert = builder.create();
alert.show();
}
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"/>
我不确定基于位置的服务是否可以从GPS以外的其他基础设施获取位置，但根据那篇文章，这似乎是可能的：
应用程序可以调用几种类型的定位方法。使用移动电话网络：当前单元格ID可用于识别基站收发信机（BTS）设备正在通信以及该BTS的位置。显然，这种方法的准确性取决于单元格的大小，以及可能非常不准确。GSM蜂窝可以是2到20直径千米。另外与细胞ID一起使用的技术可以精度在150米以内。使用卫星：全球定位系统（GPS），受控美国国防部使用由24颗卫星组成的星座围绕地球运行。GPS确定通过计算设备的位置时间差信号来自不同的卫星到达接受者GPS信号是编码的，所以移动设备必须配备使用GPS接收器。GPS是可能是最准确的方法（如果GPS接收机具有清晰的天空视图），但它也有一些缺点：硬件可能很昂贵电池使用时，需要冷启动后的热身对可见卫星的初步定位。它还受到“峡谷效应”的影响在城市，卫星能见度是间歇性的。使用短程定位信标：相对小面积，如单个建筑，局域网可以提供其他位置服务。例如，适当地配备的设备可以使用蓝牙短程定位。
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。
public static Location getBestLocation(Context ctxt) {
Location gpslocation = getLocationByProvider(
LocationManager.GPS_PROVIDER, ctxt);
Location networkLocation = getLocationByProvider(
LocationManager.NETWORK_PROVIDER, ctxt);
Location fetchedlocation = null;
// if we have only one location available, the choice is easy
if (gpslocation != null) {
Log.i("New Location Receiver", "GPS Location available.");
fetchedlocation = gpslocation;
} else {
Log.i("New Location Receiver",
"No GPS Location available. Fetching Network location lat="
+ networkLocation.getLatitude() + " lon ="
+ networkLocation.getLongitude());
fetchedlocation = networkLocation;
}
return fetchedlocation;
}
/**
* get the last known location from a specific provider (network/gps)
*/
private static Location getLocationByProvider(String provider, Context ctxt) {
Location location = null;
// if (!isProviderSupported(provider)) {
// return null;
// }
LocationManager locationManager = (LocationManager) ctxt
.getSystemService(Context.LOCATION_SERVICE);
try {
if (locationManager.isProviderEnabled(provider)) {
location = locationManager.getLastKnownLocation(provider);
}
} catch (IllegalArgumentException e) {
Log.i("New Location Receiver", "Cannot access Provider " + provider);
}
return location;
}
