存在的问题:
尽快在阈值范围内获取用户的当前位置，同时节省电池。
为什么这个问题是问题:
首先，android有两个提供者;网络和GPS。有时网络更好，有时GPS更好。
这里的“更好”指的是速度与准确度之比。
我愿意牺牲几米的精度，只要我能在不打开GPS的情况下立即得到位置。
其次，如果您请求更新位置更改，如果当前位置稳定，则不会发送任何内容。
谷歌有一个确定“最佳”位置的例子:http://developer.android.com/guide/topics/location/obtaining-user-location.html#BestEstimate
但是我认为它远不如它应该/可以做到的那么好。
我有点困惑为什么谷歌没有一个规范化的API的位置，开发人员不应该关心位置从哪里来，你应该指定你想要什么，手机应该为你选择。
我需要帮助的方面:
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或第三方库。
这并不意味着要确定最好的提供者!
我可能会使用所有的提供者，并从中选择最好的。
app背景:
该应用程序将在固定的时间间隔(比如每10分钟左右)收集用户的位置，并将其发送到服务器。
应用程序应该尽可能节省电池，位置应该有X(50-100?)米的精度。
我们的目标是以后能够在地图上绘制用户白天的路径，所以我需要足够的准确性。
Misc:
你认为期望和接受的精确度的合理值是多少?
我一直在用接受的100万和想要的30万，这要求太高了吗?
我希望以后能够在地图上绘制用户的路径。
要求100米，接受500米更好吗?
另外，现在我的GPS每次更新位置最多60秒，如果你在室内，精度可能是200米，这是不是太短了?
这是我目前的代码，任何反馈都是赞赏的(除了缺乏错误检查，这是TODO):
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);
}
最近重构得到的位置代码，学习了一些不错的思路，最后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();
}
}
}
}
完整的实现:
https://github.com/bingerz/FastLocation/blob/master/fastlocationlib/src/main/java/cn/bingerz/fastlocation/FastLocation.java
1.谢谢@Gryphius解决方案的想法，我也分享了完整的代码。
2.每次请求完成位置时，最好删除更新，否则手机状态栏会一直显示定位图标
最近重构得到的位置代码，学习了一些不错的思路，最后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();
}
}
}
}
完整的实现:
https://github.com/bingerz/FastLocation/blob/master/fastlocationlib/src/main/java/cn/bingerz/fastlocation/FastLocation.java
1.谢谢@Gryphius解决方案的想法，我也分享了完整的代码。
2.每次请求完成位置时，最好删除更新，否则手机状态栏会一直显示定位图标
