通過GPS獲取用戶位置然後網絡然後Wifi

Question

我有一個服務在那種作品。它會檢查GPS是否啓用，是否會獲取GPS位置，並且我的地圖可以縮放到該位置。它有getLastKnownLocation。問題是，getLastKnownLocation可能在數英里之外（就像我昨天試過的那樣）。

首先運行GPS支票，因爲它使得它不運行位置的網絡檢查。

是否有如果啓用了GPS有它，這樣一種方式，但不能比getLastKnownLcation（其它修復）是將默認爲基於網絡的位置？之後，我會檢查，如果網絡未啓用或lastKnownLocation太遠，我可以檢查Wifi。

這裏是我的服務代碼：

public class GPSTracker extends Service implements LocationListener { 

private final Context mContext; 
boolean isGPSEnabled = false; 
boolean isNetworkEnabled = false; 
boolean canGetLocation = false; 

Location location; 
double latitude; 
double longitude; 

//Minimum distance for update 
private static final long MIN_DISTANCE_CHANGE_FOR_UPDATES = 10; //10 meters 

// The minimum time between updates in milliseconds 
private static final long MIN_TIME_BW_UPDATES = 1000 * 40; //40 seconds 

protected LocationManager locationManager; 

public GPSTracker(Context context) { 
    this.mContext = context; 
    getLocation(); 
} 

public Location getLocation() { 
    Log.i("i", "Get location called"); 

    locationManager = (LocationManager) mContext.getSystemService(LOCATION_SERVICE); 

    //Getting GPS status 
    isGPSEnabled = locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER); 

    //Getting network status 
    isNetworkEnabled = locationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER); 
    this.canGetLocation = true; 
    if (isGPSEnabled) { 
     if (location == null) { 
      locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, MIN_TIME_BW_UPDATES, MIN_DISTANCE_CHANGE_FOR_UPDATES, this); 
      Log.d("GPS Enabled", "GPS Enabled"); 
      if (locationManager != null) { 
       location = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER); 
       if (location != null) { 
        latitude = location.getLatitude(); 
        longitude = location.getLongitude(); 
        Log.i("GPS_LOCATION", "Location: "+location.toString()); 
        if(location.toString().contains("0.000000")) { 
         Log.i("Called", "Called inside"); 
         isNetworkEnabled = true; 
         isGPSEnabled = false; 
         getLocation(); 
        } 
       } 
      } 
     } 
    } 
    else if (isNetworkEnabled) { 
     Log.d("Network", "Network"); 
     locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, MIN_TIME_BW_UPDATES, MIN_DISTANCE_CHANGE_FOR_UPDATES, this); 
     if (locationManager != null) { 
      location = locationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER); 
      if (location != null) { 
       latitude = location.getLatitude(); 
       longitude = location.getLongitude(); 
       Log.i("NETWORK_LOCATION", "Location: "+location.toString()); 
      } 
     } 
    } 
    else if (!isGPSEnabled && !isNetworkEnabled) { 
     // no network provider is enabled and GPS is off. 
     Log.d("NOT ENABLED", "Use WIFI"); 
    } 
    return location; 
} 

發生了什麼事昨天，我去幾英里遠從我的家，有一個WiFi連接，並且有GPS功能，但實際情況是，雖然我的位置通過Wifi更新，地圖上的藍點。它不會放大它。由於GPS已啓用（但無法修復），它沿着該路線前進，並得到LastKnownLocation()，這是在我家。即使藍點是正確的，它仍然保持縮放到我上次所在的位置。

有沒有一種方法，我可以擁有它，這樣它會檢查GPS，但不使用LastKnownLocation？它改爲默認爲網絡檢查，然後網絡檢查將不會使用lastknownLocation，它將默認爲Wifi。如果需要，Wifi可以擁有LastKnownLocation。實際上，我只想在Wifi階段獲得lastKnownLocation作爲最後的手段。

希望有人能幫助我在此。我認爲這不像從代碼中移除lastKnownLocation那麼簡單。

感謝您提供的任何幫助。

Answer 1

有各種各樣的方法來做到這一點。以下是一些提示：

1. 請勿使用舊的LastKnownLocation。先檢查年齡！
2. 位置提供了通過getProvider()的供應商，請檢查您先將您的最高優先級，然後在二次加工。
3. 以最高精度使用GPS。

你可能要仔細看看Location Strategies，特別是isBetterLocation函數。你可能想要這樣的東西，雖然你需要調整它以適應你的需求。

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); 
}