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);
}

当前回答

看起来我们在编写相同的应用程序;-) 这是我当前的实现。我的GPS上传应用程序仍处于beta测试阶段,因此可能会有许多可能的改进。但到目前为止,它似乎运行得很好。

/**
 * 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:这里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
}

需要考虑的事情:

不要太频繁地要求更新GPS,这会消耗电池电量。我目前 使用30分钟作为默认的应用程序。 增加“到最后已知位置的最小距离”检查。没有这个,你的分数 当GPS无法使用,位置被三角定位时,会“跳来跳去”吗 从发射塔传来的。或者您可以检查新位置是否在精度范围之外 最后一个已知位置的值。

其他回答

回答前两点:

GPS总是会给你一个更精确的位置,如果它被启用,如果周围没有厚墙。 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数据库(例如,http://www.location-api.com/或http://opencellid.org/)引用单元格位置。


策略是在读取位置时读取塔id列表。然后,在下一次查询中(在你的应用程序中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,那么等待onLocationChanged()。这避免了对位置的第三方数据库的需要。您也可以尝试这种方法。

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

看起来我们在编写相同的应用程序;-) 这是我当前的实现。我的GPS上传应用程序仍处于beta测试阶段,因此可能会有许多可能的改进。但到目前为止,它似乎运行得很好。

/**
 * 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:这里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
}

需要考虑的事情:

不要太频繁地要求更新GPS,这会消耗电池电量。我目前 使用30分钟作为默认的应用程序。 增加“到最后已知位置的最小距离”检查。没有这个,你的分数 当GPS无法使用,位置被三角定位时,会“跳来跳去”吗 从发射塔传来的。或者您可以检查新位置是否在精度范围之外 最后一个已知位置的值。

根据我的经验,我发现最好使用GPS修复,除非它不可用。我不太了解其他位置提供商,但我知道对于GPS来说,有一些技巧可以用来提供一个小范围的精确测量。海拔高度通常是一个符号,所以你可以检查一些荒谬的值。Android定位修复有准确性测量。此外,如果你能看到使用的卫星数量,这也可以表明精度。

要更好地了解精确度,一个有趣的方法是快速地请求一组修复,比如10秒内每秒1次,然后休眠一两分钟。我参加过的一个演讲让我相信一些android设备无论如何都会做到这一点。然后,您将剔除异常值(我在这里听到过卡尔曼滤波器),并使用某种集中策略来获得单个修复。

显然,你能达到的深度取决于你的要求有多难。如果你对尽可能获得最佳位置有特别严格的要求,我想你会发现GPS和网络定位就像苹果和橘子一样相似。另外,GPS在不同的设备上也有很大的不同。

要为你的应用程序选择正确的位置提供者,你可以使用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,了解如何考虑参数的更多细节:

通知的频率可以使用minTime和 minDistance参数。如果minTime大于0,则LocationManager . properties将自动返回 可能会在位置更新之间休息minTime毫秒 为了节约能源。如果minDistance大于0,一个位置只会 如果设备按minDistance米移动,则广播。获得 尽可能频繁地通知,将两个参数都设置为0。

更多的想法

You can monitor the accuracy of the Location objects with Location.getAccuracy(), which returns the estimated accuracy of the position in meters. the Criteria.ACCURACY_HIGH criterion should give you errors below 100m, which is not as good as GPS can be, but matches your needs. You also need to monitor the status of your location provider, and switch to another provider if it gets unavailable or disabled by the user. The passive provider may also be a good match for this kind of application: the idea is to use location updates whenever they are requested by another app and broadcast systemwide.