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
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;
}
其中一些人现在已经过时了，所以我回答说，
FusedLocationProviderClient fusedLocationProviderClient; //set global variable
Location currentLocation;//set global var
private boolean mLocationPermissionGranted; //set global var
fusedLocationProviderClient = LocationServices.getFusedLocationProviderClient(getContext()); //write this oncreate
fetchLastLocation(); // call the funct for current location
//here is the function
private void fetchLastLocation() {
if (ActivityCompat.checkSelfPermission(getContext(), Manifest.permission.ACCESS_FINE_LOCATION)
!= PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(getActivity(),new String[]{
Manifest.permission.ACCESS_FINE_LOCATION},REQUEST_CODE);
return;
}else {
mLocationPermissionGranted=true;
}
Task<Location> task= fusedLocationProviderClient.getLastLocation();
task.addOnSuccessListener(new OnSuccessListener<Location>() {
@Override
public void onSuccess(Location location) {
if(location != null){
currentLocation =location;
Toast.makeText(getContext(), currentLocation.getLatitude()+"" +
" "+currentLocation.getLongitude(),
Toast.LENGTH_SHORT).show();
//if you want to show in google maps
SupportMapFragment supportMapFragment =(SupportMapFragment)
getChildFragmentManager().findFragmentById(R.id.map);
supportMapFragment.getMapAsync(MapsFragment.this);
}
}
});
}
你可以一直使用LocationManager.getLastKnownLocation（），但就像它说的那样，它可能已经过时了。
获取一般位置的一个简单方法是注册网络（通常很快）。
LocationManager locationManager = (LocationManager) this.getSystemService(Context.LOCATION_SERVICE);
locationManager.requestLocationUpdates(
LocationManager.NETWORK_PROVIDER, 1000, 1000, this);
然后做
locationManager.removeUpdates(this);
在侦听器的onLocationChanged（）方法中。
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，我检查是否启用了网络或GPS提供商。有些可能在设备上禁用，有些可能在应用程序清单中禁用。如果启用了任何提供程序，我将获取该提供程序的缓存最后位置，并启动该提供程序位置更新侦听器。有一种方法可以确定某个位置是否优于链接中提到的上次接收位置：-https://developer.android.com/guide/topics/location/strategies.html#BestEstimate如果我从位置侦听器获得更新，我会检查这个位置是否比以前接收的位置更好。以及如果它比将此位置替换为先前的最佳位置（mFinalLocation）更好。还有一个两分钟的处理程序（计时器），它最终会停止服务，在服务的onDestroy（）方法中，停止侦听每个提供程序的位置更新。
以下是服务代码。您可以根据需要的位置更新频率运行它。
import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.os.Handler;
import android.os.IBinder;
import android.os.Message;
import android.support.annotation.Nullable;
import android.util.Log;
public class RecordLocationService extends Service {
private final String TAG = RecordLocationService.class.getSimpleName();
private final int TWO_MINUTES = 1000 * 60 * 2;
private LocationManager mLocationManager;
private MyLocationListener mLocationListeners[] = new MyLocationListener[]{
new MyLocationListener(LocationManager.NETWORK_PROVIDER),
new MyLocationListener(LocationManager.GPS_PROVIDER)
};
private Location mFinalLocation;
private class MyLocationListener implements LocationListener {
private String mProvider;
public MyLocationListener(String provider) {
Log.d(TAG, "LocationListener : " + provider);
mProvider = provider;
}
public String getProvider() {
return mProvider;
}
@Override
public void onLocationChanged(Location location) {
Log.d(TAG, "onLocationChanged : " + location);
if (isBetterLocation(location, mFinalLocation)) {
Log.d(TAG, "Setting current Final Location to recent most Location for Provider : " + location.getProvider());
Log.d(TAG, "Setting current Final Location to : " + location);
mFinalLocation = location;
} else {
Log.d(TAG, "Keeping current Final Location to previous Final Location");
}
}
@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
Log.d(TAG, "onStatusChanged provider " + provider);
}
@Override
public void onProviderEnabled(String provider) {
Log.d(TAG, "onProviderEnabled provider " + provider);
}
@Override
public void onProviderDisabled(String provider) {
Log.d(TAG, "onProviderDisabled provider " + provider);
}
}
private Handler mStopServiceHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
switch (msg.what) {
case 1: {
stopSelf();
}
break;
}
}
};
@Nullable
@Override
public IBinder onBind(Intent intent) {
return null;
}
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
super.onStartCommand(intent, flags, startId);
Log.d(TAG, "onStartCommand");
return START_STICKY;
}
@Override
public void onCreate() {
super.onCreate();
Log.d(TAG, "onCreate");
requestLocation();
mStopServiceHandler.sendEmptyMessageDelayed(1, TWO_MINUTES);
}
private void requestLocation() {
// Acquire a reference to the system Location Manager
if (mLocationManager == null) {
mLocationManager = (LocationManager) this.getApplicationContext().getSystemService(Context.LOCATION_SERVICE);
}
try {
if (mLocationManager.getAllProviders().contains(LocationManager.NETWORK_PROVIDER) && mLocationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER)) {
Log.d(TAG, "Fetching Cached Location for Provider : " + LocationManager.NETWORK_PROVIDER);
Location cachedNetworkLocation = mLocationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
if (cachedNetworkLocation != null) {
Log.d(TAG, "Setting Final Location to Cached Location for Provider : " + LocationManager.NETWORK_PROVIDER);
Log.d(TAG, "Setting Final Location to : " + cachedNetworkLocation);
mFinalLocation = cachedNetworkLocation;
} else {
Log.d(TAG, "Cached Location for Provider : " + LocationManager.NETWORK_PROVIDER + " is NULL");
}
Log.d(TAG, "Requesting Location Update for Provider : " + LocationManager.NETWORK_PROVIDER);
mLocationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 0, 0, mLocationListeners[0]);
}
} catch (SecurityException se) {
Log.e(TAG, se.getMessage(), se);
} catch (IllegalArgumentException iae) {
Log.e(TAG, iae.getMessage(), iae);
}
try {
if (mLocationManager.getAllProviders().contains(LocationManager.GPS_PROVIDER) && mLocationManager.isProviderEnabled(LocationManager.GPS_PROVIDER)) {
Log.d(TAG, "Fetching Cached Location for Provider : " + LocationManager.GPS_PROVIDER);
Location cachedGPSLocation = mLocationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
if (cachedGPSLocation != null) {
if (isBetterLocation(cachedGPSLocation, mFinalLocation)) {
Log.d(TAG, "Setting Final Location to Cached Location for Provider : " + LocationManager.GPS_PROVIDER);
Log.d(TAG, "Setting Final Location to : " + cachedGPSLocation);
mFinalLocation = cachedGPSLocation;
}
} else {
Log.d(TAG, "Cached Location for Provider : " + LocationManager.GPS_PROVIDER + " is NULL");
}
Log.d(TAG, "Requesting Location Update for Provider : " + LocationManager.GPS_PROVIDER);
mLocationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, mLocationListeners[1]);
}
} catch (SecurityException se) {
Log.e(TAG, se.getMessage(), se);
} catch (IllegalArgumentException iae) {
Log.e(TAG, iae.getMessage(), iae);
}
}
/**
* Determines whether one Location reading is better than the current Location fix
*
* @param location The new Location that you want to evaluate
* @param currentBestLocation The current Location fix, to which you want to compare the new one
*/
protected boolean isBetterLocation(Location location, Location currentBestLocation) {
if (currentBestLocation == null) {
// A new location is always better than no location
return true;
}
// Check whether the new location fix is newer or older
long timeDelta = location.getTime() - currentBestLocation.getTime();
boolean isSignificantlyNewer = timeDelta > TWO_MINUTES;
boolean isSignificantlyOlder = timeDelta < -TWO_MINUTES;
boolean isNewer = timeDelta > 0;
// If it's been more than two minutes since the current location, use the new location
// because the user has likely moved
if (isSignificantlyNewer) {
return true;
// If the new location is more than two minutes older, it must be worse
} else if (isSignificantlyOlder) {
return false;
}
// Check whether the new location fix is more or less accurate
int accuracyDelta = (int) (location.getAccuracy() - currentBestLocation.getAccuracy());
boolean isLessAccurate = accuracyDelta > 0;
boolean isMoreAccurate = accuracyDelta < 0;
boolean isSignificantlyLessAccurate = accuracyDelta > 200;
// Check if the old and new location are from the same provider
boolean isFromSameProvider = isSameProvider(location.getProvider(),
currentBestLocation.getProvider());
// Determine location quality using a combination of timeliness and accuracy
if (isMoreAccurate) {
return true;
} else if (isNewer && !isLessAccurate) {
return true;
} else if (isNewer && !isSignificantlyLessAccurate && isFromSameProvider) {
return true;
}
return false;
}
/**
* Checks whether two providers are the same
*/
private boolean isSameProvider(String provider1, String provider2) {
if (provider1 == null) {
return provider2 == null;
}
return provider1.equals(provider2);
}
@Override
public void onDestroy() {
super.onDestroy();
Log.d(TAG, "onDestroy");
if (mLocationManager != null) {
for (int i = 0; i < mLocationListeners.length; i++) {
try {
Log.d(TAG, "Removing Location Update for Provider : " + mLocationListeners[i].getProvider());
mLocationManager.removeUpdates(mLocationListeners[i]);
} catch (Exception ex) {
Log.e(TAG, "fail to remove location listeners, ignore", ex);
}
}
}
}
}
