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
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。
其他回答
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。
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();
}
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;
}
要获取并显示用户的当前位置，还可以使用MyLocationOverlay。假设您的活动中有一个mapView字段。要显示用户位置，只需执行以下操作：
myLocationOverlay = new MyLocationOverlay(this, mapView);
myLocationOverlay.enableMyLocation();
mapView.getOverlays().add(myLocationOverlay);
这将从GPS或网络获取当前位置。如果两者都失败，enableMyLocation（）将返回false。
至于该区域周围事物的位置，ItemizedOverlay应该可以做到这一点。
我希望我没有误解你的问题。祝你好运
在搜索了如何获得最佳精确用户位置的最佳实现后，我成功地结合了所有最佳方法，并提出了以下类：
/**
* Retrieve accurate location from GPS or network services.
*
*
* Class usage example:
*
* public void onCreate(Bundle savedInstanceState) {
* ...
* my_location = new MyLocation();
* my_location.init(main.this, locationResult);
* }
*
*
* public LocationResult locationResult = new LocationResult(){
* @Override
* public void gotLocation(final Location location){
* // do something
* location.getLongitude();
* location.getLatitude();
* }
* };
*/
class MyLocation{
/**
* If GPS is enabled.
* Use minimal connected satellites count.
*/
private static final int min_gps_sat_count = 5;
/**
* Iteration step time.
*/
private static final int iteration_timeout_step = 500;
LocationResult locationResult;
private Location bestLocation = null;
private Handler handler = new Handler();
private LocationManager myLocationManager;
public Context context;
private boolean gps_enabled = false;
private int counts = 0;
private int sat_count = 0;
private Runnable showTime = new Runnable() {
public void run() {
boolean stop = false;
counts++;
System.println("counts=" + counts);
//if timeout (1 min) exceeded, stop tying
if(counts > 120){
stop = true;
}
//update last best location
bestLocation = getLocation(context);
//if location is not ready or don`t exists, try again
if(bestLocation == null && gps_enabled){
System.println("BestLocation not ready, continue to wait");
handler.postDelayed(this, iteration_timeout_step);
}else{
//if best location is known, calculate if we need to continue to look for better location
//if gps is enabled and min satellites count has not been connected or min check count is smaller then 4 (2 sec)
if(stop == false && !needToStop()){
System.println("Connected " + sat_count + " sattelites. continue waiting..");
handler.postDelayed(this, iteration_timeout_step);
}else{
System.println("#########################################");
System.println("BestLocation found return result to main. sat_count=" + sat_count);
System.println("#########################################");
// removing all updates and listeners
myLocationManager.removeUpdates(gpsLocationListener);
myLocationManager.removeUpdates(networkLocationListener);
myLocationManager.removeGpsStatusListener(gpsStatusListener);
sat_count = 0;
// send best location to locationResult
locationResult.gotLocation(bestLocation);
}
}
}
};
/**
* Determine if continue to try to find best location
*/
private Boolean needToStop(){
if(!gps_enabled){
return true;
}
else if(counts <= 4){
return false;
}
if(sat_count < min_gps_sat_count){
//if 20-25 sec and 3 satellites found then stop
if(counts >= 40 && sat_count >= 3){
return true;
}
return false;
}
}
return true;
}
/**
* Best location abstract result class
*/
public static abstract class LocationResult{
public abstract void gotLocation(Location location);
}
/**
* Initialize starting values and starting best location listeners
*
* @param Context ctx
* @param LocationResult result
*/
public void init(Context ctx, LocationResult result){
context = ctx;
locationResult = result;
myLocationManager = (LocationManager) context.getSystemService(Context.LOCATION_SERVICE);
gps_enabled = (Boolean) myLocationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);
bestLocation = null;
counts = 0;
// turning on location updates
myLocationManager.requestLocationUpdates("network", 0, 0, networkLocationListener);
myLocationManager.requestLocationUpdates("gps", 0, 0, gpsLocationListener);
myLocationManager.addGpsStatusListener(gpsStatusListener);
// starting best location finder loop
handler.postDelayed(showTime, iteration_timeout_step);
}
/**
* GpsStatus listener. OnChainged counts connected satellites count.
*/
public final GpsStatus.Listener gpsStatusListener = new GpsStatus.Listener() {
public void onGpsStatusChanged(int event) {
if(event == GpsStatus.GPS_EVENT_SATELLITE_STATUS){
try {
// Check number of satellites in list to determine fix state
GpsStatus status = myLocationManager.getGpsStatus(null);
Iterable<GpsSatellite>satellites = status.getSatellites();
sat_count = 0;
Iterator<GpsSatellite>satI = satellites.iterator();
while(satI.hasNext()) {
GpsSatellite satellite = satI.next();
System.println("Satellite: snr=" + satellite.getSnr() + ", elevation=" + satellite.getElevation());
sat_count++;
}
} catch (Exception e) {
e.printStackTrace();
sat_count = min_gps_sat_count + 1;
}
System.println("#### sat_count = " + sat_count);
}
}
};
/**
* Gps location listener.
*/
public final LocationListener gpsLocationListener = new LocationListener(){
@Override
public void onLocationChanged(Location location){
}
public void onProviderDisabled(String provider){}
public void onProviderEnabled(String provider){}
public void onStatusChanged(String provider, int status, Bundle extras){}
};
/**
* Network location listener.
*/
public final LocationListener networkLocationListener = new LocationListener(){
@Override
public void onLocationChanged(Location location){
}
public void onProviderDisabled(String provider){}
public void onProviderEnabled(String provider){}
public void onStatusChanged(String provider, int status, Bundle extras){}
};
/**
* Returns best location using LocationManager.getBestProvider()
*
* @param context
* @return Location|null
*/
public static Location getLocation(Context context){
System.println("getLocation()");
// fetch last known location and update it
try {
LocationManager lm = (LocationManager) context.getSystemService(Context.LOCATION_SERVICE);
Criteria criteria = new Criteria();
criteria.setAccuracy(Criteria.ACCURACY_FINE);
criteria.setAltitudeRequired(false);
criteria.setBearingRequired(false);
criteria.setCostAllowed(true);
String strLocationProvider = lm.getBestProvider(criteria, true);
System.println("strLocationProvider=" + strLocationProvider);
Location location = lm.getLastKnownLocation(strLocationProvider);
if(location != null){
return location;
}
return null;
} catch (Exception e) {
e.printStackTrace();
return null;
}
}
}
如果启用gps，此类将尝试连接到min_gps_sat_count卫星。Else返回LocationManager.getBestProvider（）位置。检查代码！
