问题:
尽快让用户的当前位置在阈值范围内,同时节省电池。
为什么问题是问题:
首先,android 有两个提供者;网络和 GPS。有时网络更好,有时 GPS 更好。
“更好”是指速度与准确率的比值。如果我可以在不打开 GPS 的情况下几乎立即获得位置,我愿意牺牲几米的精度。
其次,如果您请求更新位置更改,则如果当前位置稳定,则不会发送任何内容。
Google 在此处提供了一个确定“最佳”位置的示例:http://developer.android.com/guide/topics/location/obtaining-user-location.html#BestEstimate
但我认为它远没有它应该/可能的那么好。
我有点困惑,为什么谷歌没有标准化的位置 API,开发人员不必关心位置的来源,你应该指定你想要的,手机应该为你选择。
我需要帮助:
我需要找到一种确定“最佳”位置的好方法,可能是通过一些启发式方法或通过一些第 3 方库。
这并不意味着确定最佳提供商!我可能会使用所有提供商并从中挑选出最好的。
应用背景:
该应用程序将以固定的时间间隔(假设每 10 分钟左右)收集用户的位置并将其发送到服务器。该应用程序应尽可能节省电池电量,并且该位置应具有 X (50-100?) 米的精度。
目标是以后能够在地图上绘制用户白天的路径,因此我需要足够的准确性。
杂项:
您认为期望和接受的准确度的合理值是多少?我一直在使用 100m 作为接受和 30m 作为期望,这要求太多了吗?我希望以后能够在地图上绘制用户的路径。 100m 的期望值和 500m 的接受度更好吗?
另外,现在我每次更新位置的 GPS 最多开启 60 秒,如果您在室内,精度可能为 200m,这是否太短而无法获得位置?
这是我当前的代码,任何反馈都表示赞赏(除了缺少 TODO 的错误检查):
protected void runTask() {
final LocationManager locationManager = (LocationManager) context
.getSystemService(Context.LOCATION_SERVICE);
updateBestLocation(locationManager
.getLastKnownLocation(LocationManager.GPS_PROVIDER));
updateBestLocation(locationManager
.getLastKnownLocation(LocationManager.NETWORK_PROVIDER));
if (getLocationQuality(bestLocation) != LocationQuality.GOOD) {
Looper.prepare();
setLooper(Looper.myLooper());
// Define a listener that responds to location updates
LocationListener locationListener = new LocationListener() {
public void onLocationChanged(Location location) {
updateBestLocation(location);
if (getLocationQuality(bestLocation) != LocationQuality.GOOD)
return;
// We're done
Looper l = getLooper();
if (l != null) l.quit();
}
public void onProviderEnabled(String provider) {}
public void onProviderDisabled(String provider) {}
public void onStatusChanged(String provider, int status,
Bundle extras) {
// TODO Auto-generated method stub
Log.i("LocationCollector", "Fail");
Looper l = getLooper();
if (l != null) l.quit();
}
};
// Register the listener with the Location Manager to receive
// location updates
locationManager.requestLocationUpdates(
LocationManager.GPS_PROVIDER, 1000, 1, locationListener,
Looper.myLooper());
locationManager.requestLocationUpdates(
LocationManager.NETWORK_PROVIDER, 1000, 1,
locationListener, Looper.myLooper());
Timer t = new Timer();
t.schedule(new TimerTask() {
@Override
public void run() {
Looper l = getLooper();
if (l != null) l.quit();
// Log.i("LocationCollector",
// "Stopping collector due to timeout");
}
}, MAX_POLLING_TIME);
Looper.loop();
t.cancel();
locationManager.removeUpdates(locationListener);
setLooper(null);
}
if (getLocationQuality(bestLocation) != LocationQuality.BAD)
sendUpdate(locationToString(bestLocation));
else Log.w("LocationCollector", "Failed to get a location");
}
private enum LocationQuality {
BAD, ACCEPTED, GOOD;
public String toString() {
if (this == GOOD) return "Good";
else if (this == ACCEPTED) return "Accepted";
else return "Bad";
}
}
private LocationQuality getLocationQuality(Location location) {
if (location == null) return LocationQuality.BAD;
if (!location.hasAccuracy()) return LocationQuality.BAD;
long currentTime = System.currentTimeMillis();
if (currentTime - location.getTime() < MAX_AGE
&& location.getAccuracy() <= GOOD_ACCURACY)
return LocationQuality.GOOD;
if (location.getAccuracy() <= ACCEPTED_ACCURACY)
return LocationQuality.ACCEPTED;
return LocationQuality.BAD;
}
private synchronized void updateBestLocation(Location location) {
bestLocation = getBestLocation(location, bestLocation);
}
// Pretty much an unmodified version of googles example
protected Location getBestLocation(Location location,
Location currentBestLocation) {
if (currentBestLocation == null) {
// A new location is always better than no location
return location;
}
if (location == null) return currentBestLocation;
// 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 location;
// If the new location is more than two minutes older, it must be
// worse
} else if (isSignificantlyOlder) {
return currentBestLocation;
}
// 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 location;
} else if (isNewer && !isLessAccurate) {
return location;
} else if (isNewer && !isSignificantlyLessAccurate
&& isFromSameProvider) {
return location;
}
return bestLocation;
}
/** Checks whether two providers are the same */
private boolean isSameProvider(String provider1, String provider2) {
if (provider1 == null) {
return provider2 == null;
}
return provider1.equals(provider2);
}
看起来我们正在编写相同的应用程序;-) 这是我当前的实现。我的 GPS 上传器应用程序仍处于 beta 测试阶段,因此可能会有很多改进。但到目前为止它似乎工作得很好。
/**
* try to get the 'best' location selected from all providers
*/
private Location getBestLocation() {
Location gpslocation = getLocationByProvider(LocationManager.GPS_PROVIDER);
Location networkLocation =
getLocationByProvider(LocationManager.NETWORK_PROVIDER);
// if we have only one location available, the choice is easy
if (gpslocation == null) {
Log.d(TAG, "No GPS Location available.");
return networkLocation;
}
if (networkLocation == null) {
Log.d(TAG, "No Network Location available");
return gpslocation;
}
// a locationupdate is considered 'old' if its older than the configured
// update interval. this means, we didn't get a
// update from this provider since the last check
long old = System.currentTimeMillis() - getGPSCheckMilliSecsFromPrefs();
boolean gpsIsOld = (gpslocation.getTime() < old);
boolean networkIsOld = (networkLocation.getTime() < old);
// gps is current and available, gps is better than network
if (!gpsIsOld) {
Log.d(TAG, "Returning current GPS Location");
return gpslocation;
}
// gps is old, we can't trust it. use network location
if (!networkIsOld) {
Log.d(TAG, "GPS is old, Network is current, returning network");
return networkLocation;
}
// both are old return the newer of those two
if (gpslocation.getTime() > networkLocation.getTime()) {
Log.d(TAG, "Both are old, returning gps(newer)");
return gpslocation;
} else {
Log.d(TAG, "Both are old, returning network(newer)");
return networkLocation;
}
}
/**
* get the last known location from a specific provider (network/gps)
*/
private Location getLocationByProvider(String provider) {
Location location = null;
if (!isProviderSupported(provider)) {
return null;
}
LocationManager locationManager = (LocationManager) getApplicationContext()
.getSystemService(Context.LOCATION_SERVICE);
try {
if (locationManager.isProviderEnabled(provider)) {
location = locationManager.getLastKnownLocation(provider);
}
} catch (IllegalArgumentException e) {
Log.d(TAG, "Cannot acces Provider " + provider);
}
return location;
}
编辑:这是请求位置提供者定期更新的部分:
public void startRecording() {
gpsTimer.cancel();
gpsTimer = new Timer();
long checkInterval = getGPSCheckMilliSecsFromPrefs();
long minDistance = getMinDistanceFromPrefs();
// receive updates
LocationManager locationManager = (LocationManager) getApplicationContext()
.getSystemService(Context.LOCATION_SERVICE);
for (String s : locationManager.getAllProviders()) {
locationManager.requestLocationUpdates(s, checkInterval,
minDistance, new LocationListener() {
@Override
public void onStatusChanged(String provider,
int status, Bundle extras) {}
@Override
public void onProviderEnabled(String provider) {}
@Override
public void onProviderDisabled(String provider) {}
@Override
public void onLocationChanged(Location location) {
// if this is a gps location, we can use it
if (location.getProvider().equals(
LocationManager.GPS_PROVIDER)) {
doLocationUpdate(location, true);
}
}
});
// //Toast.makeText(this, "GPS Service STARTED",
// Toast.LENGTH_LONG).show();
gps_recorder_running = true;
}
// start the gps receiver thread
gpsTimer.scheduleAtFixedRate(new TimerTask() {
@Override
public void run() {
Location location = getBestLocation();
doLocationUpdate(location, false);
}
}, 0, checkInterval);
}
public void doLocationUpdate(Location l, boolean force) {
long minDistance = getMinDistanceFromPrefs();
Log.d(TAG, "update received:" + l);
if (l == null) {
Log.d(TAG, "Empty location");
if (force)
Toast.makeText(this, "Current location not available",
Toast.LENGTH_SHORT).show();
return;
}
if (lastLocation != null) {
float distance = l.distanceTo(lastLocation);
Log.d(TAG, "Distance to last: " + distance);
if (l.distanceTo(lastLocation) < minDistance && !force) {
Log.d(TAG, "Position didn't change");
return;
}
if (l.getAccuracy() >= lastLocation.getAccuracy()
&& l.distanceTo(lastLocation) < l.getAccuracy() && !force) {
Log.d(TAG,
"Accuracy got worse and we are still "
+ "within the accuracy range.. Not updating");
return;
}
if (l.getTime() <= lastprovidertimestamp && !force) {
Log.d(TAG, "Timestamp not never than last");
return;
}
}
// upload/store your location here
}
需要考虑的事项:
不要太频繁地请求 GPS 更新,它会耗尽电池电量。我目前使用 30 分钟作为我的应用程序的默认值。
添加“到最后一个已知位置的最小距离”检查。没有这个,当 GPS 不可用并且从手机信号塔对位置进行三角测量时,您的点将“跳跃”。或者您可以检查新位置是否超出上一个已知位置的准确度值。
要为您的应用选择正确的位置提供程序,您可以使用 Criteria 对象:
Criteria myCriteria = new Criteria();
myCriteria.setAccuracy(Criteria.ACCURACY_HIGH);
myCriteria.setPowerRequirement(Criteria.POWER_LOW);
// let Android select the right location provider for you
String myProvider = locationManager.getBestProvider(myCriteria, true);
// finally require updates at -at least- the desired rate
long minTimeMillis = 600000; // 600,000 milliseconds make 10 minutes
locationManager.requestLocationUpdates(myProvider,minTimeMillis,0,locationListener);
阅读 requestLocationUpdates 的文档以获取有关如何考虑参数的更多详细信息:
可以使用 minTime 和 minDistance 参数控制通知的频率。如果 minTime 大于 0,LocationManager 可能会在位置更新之间休息 minTime 毫秒以节省电力。如果 minDistance 大于 0,则仅当设备移动 minDistance 米时才会广播位置。要尽可能频繁地获取通知,请将两个参数都设置为 0。
更多想法
您可以使用 Location.getAccuracy() 监控 Location 对象的准确度,它返回以米为单位的位置估计准确度。
Criteria.ACCURACY_HIGH 标准应该给你低于 100m 的错误,这不如 GPS 好,但符合你的需要。
您还需要监控您的位置提供商的状态,并在它不可用或被用户禁用时切换到另一个提供商。
被动提供者也可能非常适合这种应用程序:这个想法是在另一个应用程序请求时使用位置更新并在系统范围内广播。
Criteria
,但如果最新的网络位置很棒(它可能通过 wifi 知道)并且不需要时间或电池来获取它(getLastKnown),那么标准可能会忽略它并返回 GPS。我不敢相信谷歌让开发人员变得如此困难。
回答前两点:
如果启用了 GPS 并且周围没有厚墙,GPS 将始终为您提供更精确的位置。
如果位置没有改变,那么您可以调用 getLastKnownLocation(String) 并立即检索位置。
使用另一种方法:
您可以尝试获取正在使用的单元格 ID 或所有相邻单元格
TelephonyManager mTelephonyManager = (TelephonyManager) getSystemService(Context.TELEPHONY_SERVICE);
GsmCellLocation loc = (GsmCellLocation) mTelephonyManager.getCellLocation();
Log.d ("CID", Integer.toString(loc.getCid()));
Log.d ("LAC", Integer.toString(loc.getLac()));
// or
List<NeighboringCellInfo> list = mTelephonyManager.getNeighboringCellInfo ();
for (NeighboringCellInfo cell : list) {
Log.d ("CID", Integer.toString(cell.getCid()));
Log.d ("LAC", Integer.toString(cell.getLac()));
}
然后,您可以通过几个开放的数据库(例如 http://www.location-api.com/ 或 http://opencellid.org/ )参考单元格位置
策略是在读取位置时读取塔 ID 列表。然后,在下一个查询中(在您的应用程序中使用 10 分钟),再次阅读它们。如果至少有一些塔是相同的,那么使用 getLastKnownLocation(String)
是安全的。如果不是,则等待 onLocationChanged()
。这避免了对该位置的第三方数据库的需要。您也可以尝试 this approach。
这是我的解决方案,效果很好:
private Location bestLocation = null;
private Looper looper;
private boolean networkEnabled = false, gpsEnabled = false;
private synchronized void setLooper(Looper looper) {
this.looper = looper;
}
private synchronized void stopLooper() {
if (looper == null) return;
looper.quit();
}
@Override
protected void runTask() {
final LocationManager locationManager = (LocationManager) service
.getSystemService(Context.LOCATION_SERVICE);
final SharedPreferences prefs = getPreferences();
final int maxPollingTime = Integer.parseInt(prefs.getString(
POLLING_KEY, "0"));
final int desiredAccuracy = Integer.parseInt(prefs.getString(
DESIRED_KEY, "0"));
final int acceptedAccuracy = Integer.parseInt(prefs.getString(
ACCEPTED_KEY, "0"));
final int maxAge = Integer.parseInt(prefs.getString(AGE_KEY, "0"));
final String whichProvider = prefs.getString(PROVIDER_KEY, "any");
final boolean canUseGps = whichProvider.equals("gps")
|| whichProvider.equals("any");
final boolean canUseNetwork = whichProvider.equals("network")
|| whichProvider.equals("any");
if (canUseNetwork)
networkEnabled = locationManager
.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
if (canUseGps)
gpsEnabled = locationManager
.isProviderEnabled(LocationManager.GPS_PROVIDER);
// If any provider is enabled now and we displayed a notification clear it.
if (gpsEnabled || networkEnabled) removeErrorNotification();
if (gpsEnabled)
updateBestLocation(locationManager
.getLastKnownLocation(LocationManager.GPS_PROVIDER));
if (networkEnabled)
updateBestLocation(locationManager
.getLastKnownLocation(LocationManager.NETWORK_PROVIDER));
if (desiredAccuracy == 0
|| getLocationQuality(desiredAccuracy, acceptedAccuracy,
maxAge, bestLocation) != LocationQuality.GOOD) {
// Define a listener that responds to location updates
LocationListener locationListener = new LocationListener() {
public void onLocationChanged(Location location) {
updateBestLocation(location);
if (desiredAccuracy != 0
&& getLocationQuality(desiredAccuracy,
acceptedAccuracy, maxAge, bestLocation)
== LocationQuality.GOOD)
stopLooper();
}
public void onProviderEnabled(String provider) {
if (isSameProvider(provider,
LocationManager.NETWORK_PROVIDER))networkEnabled =true;
else if (isSameProvider(provider,
LocationManager.GPS_PROVIDER)) gpsEnabled = true;
// The user has enabled a location, remove any error
// notification
if (canUseGps && gpsEnabled || canUseNetwork
&& networkEnabled) removeErrorNotification();
}
public void onProviderDisabled(String provider) {
if (isSameProvider(provider,
LocationManager.NETWORK_PROVIDER))networkEnabled=false;
else if (isSameProvider(provider,
LocationManager.GPS_PROVIDER)) gpsEnabled = false;
if (!gpsEnabled && !networkEnabled) {
showErrorNotification();
stopLooper();
}
}
public void onStatusChanged(String provider, int status,
Bundle extras) {
Log.i(LOG_TAG, "Provider " + provider + " statusChanged");
if (isSameProvider(provider,
LocationManager.NETWORK_PROVIDER)) networkEnabled =
status == LocationProvider.AVAILABLE
|| status == LocationProvider.TEMPORARILY_UNAVAILABLE;
else if (isSameProvider(provider,
LocationManager.GPS_PROVIDER))
gpsEnabled = status == LocationProvider.AVAILABLE
|| status == LocationProvider.TEMPORARILY_UNAVAILABLE;
// None of them are available, stop listening
if (!networkEnabled && !gpsEnabled) {
showErrorNotification();
stopLooper();
}
// The user has enabled a location, remove any error
// notification
else if (canUseGps && gpsEnabled || canUseNetwork
&& networkEnabled) removeErrorNotification();
}
};
if (networkEnabled || gpsEnabled) {
Looper.prepare();
setLooper(Looper.myLooper());
// Register the listener with the Location Manager to receive
// location updates
if (canUseGps)
locationManager.requestLocationUpdates(
LocationManager.GPS_PROVIDER, 1000, 1,
locationListener, Looper.myLooper());
if (canUseNetwork)
locationManager.requestLocationUpdates(
LocationManager.NETWORK_PROVIDER, 1000, 1,
locationListener, Looper.myLooper());
Timer t = new Timer();
t.schedule(new TimerTask() {
@Override
public void run() {
stopLooper();
}
}, maxPollingTime * 1000);
Looper.loop();
t.cancel();
setLooper(null);
locationManager.removeUpdates(locationListener);
} else // No provider is enabled, show a notification
showErrorNotification();
}
if (getLocationQuality(desiredAccuracy, acceptedAccuracy, maxAge,
bestLocation) != LocationQuality.BAD) {
sendUpdate(new Event(EVENT_TYPE, locationToString(desiredAccuracy,
acceptedAccuracy, maxAge, bestLocation)));
} else Log.w(LOG_TAG, "LocationCollector failed to get a location");
}
private synchronized void showErrorNotification() {
if (notifId != 0) return;
ServiceHandler handler = service.getHandler();
NotificationInfo ni = NotificationInfo.createSingleNotification(
R.string.locationcollector_notif_ticker,
R.string.locationcollector_notif_title,
R.string.locationcollector_notif_text,
android.R.drawable.stat_notify_error);
Intent intent = new Intent(
android.provider.Settings.ACTION_LOCATION_SOURCE_SETTINGS);
ni.pendingIntent = PendingIntent.getActivity(service, 0, intent,
PendingIntent.FLAG_UPDATE_CURRENT);
Message msg = handler.obtainMessage(ServiceHandler.SHOW_NOTIFICATION);
msg.obj = ni;
handler.sendMessage(msg);
notifId = ni.id;
}
private void removeErrorNotification() {
if (notifId == 0) return;
ServiceHandler handler = service.getHandler();
if (handler != null) {
Message msg = handler.obtainMessage(
ServiceHandler.CLEAR_NOTIFICATION, notifId, 0);
handler.sendMessage(msg);
notifId = 0;
}
}
@Override
public void interrupt() {
stopLooper();
super.interrupt();
}
private String locationToString(int desiredAccuracy, int acceptedAccuracy,
int maxAge, Location location) {
StringBuilder sb = new StringBuilder();
sb.append(String.format(
"qual=%s time=%d prov=%s acc=%.1f lat=%f long=%f",
getLocationQuality(desiredAccuracy, acceptedAccuracy, maxAge,
location), location.getTime() / 1000, // Millis to
// seconds
location.getProvider(), location.getAccuracy(), location
.getLatitude(), location.getLongitude()));
if (location.hasAltitude())
sb.append(String.format(" alt=%.1f", location.getAltitude()));
if (location.hasBearing())
sb.append(String.format(" bearing=%.2f", location.getBearing()));
return sb.toString();
}
private enum LocationQuality {
BAD, ACCEPTED, GOOD;
public String toString() {
if (this == GOOD) return "Good";
else if (this == ACCEPTED) return "Accepted";
else return "Bad";
}
}
private LocationQuality getLocationQuality(int desiredAccuracy,
int acceptedAccuracy, int maxAge, Location location) {
if (location == null) return LocationQuality.BAD;
if (!location.hasAccuracy()) return LocationQuality.BAD;
long currentTime = System.currentTimeMillis();
if (currentTime - location.getTime() < maxAge * 1000
&& location.getAccuracy() <= desiredAccuracy)
return LocationQuality.GOOD;
if (acceptedAccuracy == -1
|| location.getAccuracy() <= acceptedAccuracy)
return LocationQuality.ACCEPTED;
return LocationQuality.BAD;
}
private synchronized void updateBestLocation(Location location) {
bestLocation = getBestLocation(location, bestLocation);
}
protected Location getBestLocation(Location location,
Location currentBestLocation) {
if (currentBestLocation == null) {
// A new location is always better than no location
return location;
}
if (location == null) return currentBestLocation;
// 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 location;
// If the new location is more than two minutes older, it must be
// worse
} else if (isSignificantlyOlder) {
return currentBestLocation;
}
// 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 location;
} else if (isNewer && !isLessAccurate) {
return location;
} else if (isNewer && !isSignificantlyLessAccurate
&& isFromSameProvider) {
return location;
}
return bestLocation;
}
/** Checks whether two providers are the same */
private boolean isSameProvider(String provider1, String provider2) {
if (provider1 == null) return provider2 == null;
return provider1.equals(provider2);
}
位置准确性主要取决于所使用的位置提供程序:
GPS - 可以获得几米的精度(假设你有 GPS 接收) Wifi - 可以获得几百米的精度 蜂窝网络 - 会给你非常不准确的结果(我已经看到了 4 公里的偏差......)
如果您正在寻找它的准确性,那么 GPS 是您唯一的选择。
我已经阅读了一篇关于它的内容非常丰富的文章 here。
至于 GPS 超时 - 60 秒应该足够了,在大多数情况下甚至太多了。我认为 30 秒是可以的,有时甚至不到 5 秒...
如果您只需要一个位置,我建议在您的 onLocationChanged
方法中,一旦您收到更新,您将取消注册侦听器并避免不必要地使用 GPS。
目前我正在使用它,因为这对于获取我的应用程序的位置和计算距离是可信赖的......我将它用于我的出租车应用程序。
使用谷歌开发人员开发的融合 API,融合 GPS 传感器、磁力计、加速度计,也使用 Wifi 或手机位置来计算或估计位置。它还能够准确地在建筑物内提供位置更新。有关详细信息,请访问链接 https://developers.google.com/android/reference/com/google/android/gms/location/FusedLocationProviderApi
import android.app.Activity;
import android.location.Location;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.widget.TextView;
import android.widget.Toast;
import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.GooglePlayServicesUtil;
import com.google.android.gms.common.api.GoogleApiClient;
import com.google.android.gms.common.api.GoogleApiClient.ConnectionCallbacks;
import com.google.android.gms.common.api.GoogleApiClient.OnConnectionFailedListener;
import com.google.android.gms.location.LocationListener;
import com.google.android.gms.location.LocationRequest;
import com.google.android.gms.location.LocationServices;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
public class MainActivity extends Activity implements LocationListener,
GoogleApiClient.ConnectionCallbacks,
GoogleApiClient.OnConnectionFailedListener {
private static final long ONE_MIN = 500;
private static final long TWO_MIN = 500;
private static final long FIVE_MIN = 500;
private static final long POLLING_FREQ = 1000 * 20;
private static final long FASTEST_UPDATE_FREQ = 1000 * 5;
private static final float MIN_ACCURACY = 1.0f;
private static final float MIN_LAST_READ_ACCURACY = 1;
private LocationRequest mLocationRequest;
private Location mBestReading;
TextView tv;
private GoogleApiClient mGoogleApiClient;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (!servicesAvailable()) {
finish();
}
setContentView(R.layout.activity_main);
tv= (TextView) findViewById(R.id.tv1);
mLocationRequest = LocationRequest.create();
mLocationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
mLocationRequest.setInterval(POLLING_FREQ);
mLocationRequest.setFastestInterval(FASTEST_UPDATE_FREQ);
mGoogleApiClient = new GoogleApiClient.Builder(this)
.addApi(LocationServices.API)
.addConnectionCallbacks(this)
.addOnConnectionFailedListener(this)
.build();
if (mGoogleApiClient != null) {
mGoogleApiClient.connect();
}
}
@Override
protected void onResume() {
super.onResume();
if (mGoogleApiClient != null) {
mGoogleApiClient.connect();
}
}
@Override
protected void onPause() {d
super.onPause();
if (mGoogleApiClient != null && mGoogleApiClient.isConnected()) {
mGoogleApiClient.disconnect();
}
}
tv.setText(location + "");
// Determine whether new location is better than current best
// estimate
if (null == mBestReading || location.getAccuracy() < mBestReading.getAccuracy()) {
mBestReading = location;
if (mBestReading.getAccuracy() < MIN_ACCURACY) {
LocationServices.FusedLocationApi.removeLocationUpdates(mGoogleApiClient, this);
}
}
}
@Override
public void onConnected(Bundle dataBundle) {
// Get first reading. Get additional location updates if necessary
if (servicesAvailable()) {
// Get best last location measurement meeting criteria
mBestReading = bestLastKnownLocation(MIN_LAST_READ_ACCURACY, FIVE_MIN);
if (null == mBestReading
|| mBestReading.getAccuracy() > MIN_LAST_READ_ACCURACY
|| mBestReading.getTime() < System.currentTimeMillis() - TWO_MIN) {
LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient, mLocationRequest, this);
//Schedule a runnable to unregister location listeners
@Override
public void run() {
LocationServices.FusedLocationApi.removeLocationUpdates(mGoogleApiClient, MainActivity.this);
}
}, ONE_MIN, TimeUnit.MILLISECONDS);
}
}
}
@Override
public void onConnectionSuspended(int i) {
}
private Location bestLastKnownLocation(float minAccuracy, long minTime) {
Location bestResult = null;
float bestAccuracy = Float.MAX_VALUE;
long bestTime = Long.MIN_VALUE;
// Get the best most recent location currently available
Location mCurrentLocation = LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient);
//tv.setText(mCurrentLocation+"");
if (mCurrentLocation != null) {
float accuracy = mCurrentLocation.getAccuracy();
long time = mCurrentLocation.getTime();
if (accuracy < bestAccuracy) {
bestResult = mCurrentLocation;
bestAccuracy = accuracy;
bestTime = time;
}
}
// Return best reading or null
if (bestAccuracy > minAccuracy || bestTime < minTime) {
return null;
}
else {
return bestResult;
}
}
@Override
public void onConnectionFailed(ConnectionResult connectionResult) {
}
private boolean servicesAvailable() {
int resultCode = GooglePlayServicesUtil.isGooglePlayServicesAvailable(this);
if (ConnectionResult.SUCCESS == resultCode) {
return true;
}
else {
GooglePlayServicesUtil.getErrorDialog(resultCode, this, 0).show();
return false;
}
}
}
我使用谷歌建议的最新位置提取方法(使用 FusedLocationProviderClient)在互联网上搜索更新的(过去一年)答案。我终于找到了这个:
https://github.com/googlesamples/android-play-location/tree/master/LocationUpdates
我创建了一个新项目并复制了大部分代码。繁荣。有用。而且我认为没有任何已弃用的行。
此外,据我所知,模拟器似乎没有获得 GPS 位置。它确实在日志中报告了这一点:“所有位置设置都已满足。”
最后,如果您想知道(我知道),如果您想要的只是 GPS 位置,则不需要来自谷歌开发者控制台的 google maps api 密钥。
他们的教程也很有用。但我想要一个完整的一页教程/代码示例,等等。他们的教程堆积如山,但当您不熟悉此教程时会感到困惑,因为您不知道从前面的页面中需要哪些部分。
https://developer.android.com/training/location/index.html
最后,记住这样的事情:
我不仅要修改mainActivity.Java。我还必须修改 Strings.xml、androidmanifest.xml 和正确的 build.gradle。还有你的activity_Main.xml(但这部分对我来说很容易)。
我需要添加这样的依赖项:实现 'com.google.android.gms:play-services-location:11.8.0',并更新我的 android studio SDK 的设置以包含谷歌播放服务。 (文件设置外观系统设置android SDK SDK 工具检查谷歌播放服务)。
更新:android 模拟器似乎确实获得了位置和位置更改事件(当我更改了 sim 设置中的值时)。但我最好的和第一个结果是在实际设备上。因此,在实际设备上进行测试可能是最容易的。
最近重构获取代码的位置,学习了一些好的思路,终于实现了一个比较完善的库和Demo。
@Gryphius 的回答很好
//request all valid provider(network/gps)
private boolean requestAllProviderUpdates() {
checkRuntimeEnvironment();
checkPermission();
if (isRequesting) {
EasyLog.d("Request location update is busy");
return false;
}
long minTime = getCheckTimeInterval();
float minDistance = getCheckMinDistance();
if (mMapLocationListeners == null) {
mMapLocationListeners = new HashMap<>();
}
mValidProviders = getValidProviders();
if (mValidProviders == null || mValidProviders.isEmpty()) {
throw new IllegalArgumentException("Not available provider.");
}
for (String provider : mValidProviders) {
LocationListener locationListener = new LocationListener() {
@Override
public void onLocationChanged(Location location) {
if (location == null) {
EasyLog.e("LocationListener callback location is null.");
return;
}
printf(location);
mLastProviderTimestamp = location.getTime();
if (location.getProvider().equals(LocationManager.GPS_PROVIDER)) {
finishResult(location);
} else {
doLocationResult(location);
}
removeProvider(location.getProvider());
if (isEmptyValidProviders()) {
requestTimeoutMsgInit();
removeUpdates();
}
}
@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
}
@Override
public void onProviderEnabled(String provider) {
}
@Override
public void onProviderDisabled(String provider) {
}
};
getLocationManager().requestLocationUpdates(provider, minTime, minDistance, locationListener);
mMapLocationListeners.put(provider, locationListener);
EasyLog.d("Location request %s provider update.", provider);
}
isRequesting = true;
return true;
}
//remove request update
public void removeUpdates() {
checkRuntimeEnvironment();
LocationManager locationManager = getLocationManager();
if (mMapLocationListeners != null) {
Set<String> keys = mMapLocationListeners.keySet();
for (String key : keys) {
LocationListener locationListener = mMapLocationListeners.get(key);
if (locationListener != null) {
locationManager.removeUpdates(locationListener);
EasyLog.d("Remove location update, provider is " + key);
}
}
mMapLocationListeners.clear();
isRequesting = false;
}
}
//Compared with the last successful position, to determine whether you need to filter
private boolean isNeedFilter(Location location) {
checkLocation(location);
if (mLastLocation != null) {
float distance = location.distanceTo(mLastLocation);
if (distance < getCheckMinDistance()) {
return true;
}
if (location.getAccuracy() >= mLastLocation.getAccuracy()
&& distance < location.getAccuracy()) {
return true;
}
if (location.getTime() <= mLastProviderTimestamp) {
return true;
}
}
return false;
}
private void doLocationResult(Location location) {
checkLocation(location);
if (isNeedFilter(location)) {
EasyLog.d("location need to filtered out, timestamp is " + location.getTime());
finishResult(mLastLocation);
} else {
finishResult(location);
}
}
//Return to the finished position
private void finishResult(Location location) {
checkLocation(location);
double latitude = location.getLatitude();
double longitude = location.getLongitude();
float accuracy = location.getAccuracy();
long time = location.getTime();
String provider = location.getProvider();
if (mLocationResultListeners != null && !mLocationResultListeners.isEmpty()) {
String format = "Location result:<%f, %f> Accuracy:%f Time:%d Provider:%s";
EasyLog.i(String.format(format, latitude, longitude, accuracy, time, provider));
mLastLocation = location;
synchronized (this) {
Iterator<LocationResultListener> iterator = mLocationResultListeners.iterator();
while (iterator.hasNext()) {
LocationResultListener listener = iterator.next();
if (listener != null) {
listener.onResult(location);
}
iterator.remove();
}
}
}
}
1.感谢@Gryphius 解决思路,我也分享完整代码。
2.每次请求完成定位,最好去掉Updates,否则手机状态栏会一直显示定位图标
根据我的经验,我发现最好使用 GPS 定位,除非它不可用。我对其他位置提供商了解不多,但我知道对于 GPS,有一些技巧可以用来提供一些贫民区的精确测量。高度通常是一个标志,因此您可以检查荒谬的值。 Android 位置修复有准确度测量。此外,如果您可以看到使用的卫星数量,这也可以指示精度。
更好地了解准确性的一种有趣方法可能是非常快速地请求一组修复,例如约 1/秒 10 秒,然后休眠一两分钟。我参加过的一次演讲让我相信一些安卓设备无论如何都会这样做。然后,您将清除异常值(我听说过这里提到的卡尔曼滤波器)并使用某种居中策略来获得单一修复。
显然,您到达这里的深度取决于您的要求有多难。如果你对获得最佳位置有特别严格的要求,我想你会发现 GPS 和网络位置就像苹果和橘子一样。 GPS也可能因设备而异。
Skyhook (http://www.skyhookwireless.com/) 有一个位置提供程序,它比 Google 提供的标准速度快得多。这可能是您正在寻找的东西。我不隶属于他们。
不定期副业成功案例分享