[英]Android Location getBearing() always returns 0
我一直在嘗試為我的Android應用程序實現一項功能,該功能無論設備指向何處都可以獲取設備的速度和行進方向。 例如:如果我的Android設備指向北向,而我向南移動,則返回向南移動。
我一直在環顧四周,並且提出了使用Location的getBearing()方法的可能性(不過,我不知道這是否可以解決我的整個問題)。 當我調用getBearing()時,由於某種原因它總是返回0.0。 我不知道為什么。 這是我的代碼:
LocationManager lm;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_gcm);
setUpUI(findViewById(R.id.LinearLayout1));
isRegged = false;
// GCM startup
gcm = GoogleCloudMessaging.getInstance(this);
context = getApplicationContext();
gps = new GPSTracker(context);
// gps.startListening(context);
// gps.setGpsCall(this);
/*
* Variables to indicate location and device ID
*/
TelephonyManager telephonyManager = (TelephonyManager) getSystemService(Context.TELEPHONY_SERVICE);
if (gps.getIsGPSTrackingEnabled())
{
longitude = Double.valueOf(gps.getLongitude()).toString();
latitude = Double.valueOf(gps.getLatitude()).toString();
}
deviceID = telephonyManager.getDeviceId();
mSensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);
lm = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
lm.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, (float) 0.0,
this);
}
這就是我要承受的地方。
@Override
public void onLocationChanged(Location currentLocation)
{
float speed = 0;
float speed_mph = 0;
if (previousLocation != null)
{
float distance = currentLocation.distanceTo(previousLocation);
// time taken (in seconds)
float timeTaken = ((currentLocation.getTime() - previousLocation
.getTime()) / 1000);
// calculate speed
if (timeTaken > 0)
{
speed = getAverageSpeed(distance, timeTaken);
speed_mph = (float) (getAverageSpeed(distance, timeTaken) / 1.6);
}
if (speed >= 0)
{
info_text.setVisibility(View.VISIBLE);
info_text_mph.setVisibility(View.VISIBLE);
DecimalFormat df = new DecimalFormat("#.#");
info_text.setText("Speed: " + df.format(speed) + " " + "km/h");
info_text_mph.setText(" Speed: " + df.format(speed_mph) + " "
+ "mph");
if (speed >= 10 && lm.getProvider(LocationManager.GPS_PROVIDER).supportsBearing())
{
float degree = currentLocation.getBearing();
direction_text.setVisibility(View.VISIBLE);
Log.i(TAG, String.valueOf(degree));
if (degree == 0 && degree < 45 || degree >= 315
&& degree == 360)
{
direction_text.setText("You are: Northbound");
}
if (degree >= 45 && degree < 90)
{
direction_text.setText("You are: NorthEastbound");
}
if (degree >= 90 && degree < 135)
{
direction_text.setText("You are: Eastbound");
}
if (degree >= 135 && degree < 180)
{
direction_text.setText("You are: SouthEastbound");
}
if (degree >= 180 && degree < 225)
{
direction_text.setText("You are: SouthWestbound");
}
if (degree >= 225 && degree < 270)
{
direction_text.setText("You are: Westbound");
}
if (degree >= 270 && degree < 315)
{
direction_text.setText("You are: NorthWestbound");
}
}
}
}
previousLocation = currentLocation;
}
非常感謝!
如果您使用LocationManager.NETWORK_PROVIDER
獲取數據,則getBearing()
將返回0,因為信號/准確性太弱。 嘗試將GPS提供程序設置為GPS,並確保在室外對其進行測試(由於衛星之間沒有直接通訊,GPS無法在室內或在很高的建築物中間使用)
為了確保你選擇支持getBearing提供商(),您可以使用從方法LocationProvider
稱為supportsBearing ()
如果提供您選擇支持的返回true getBearing()
調用。
最后,確保您在AndroidManifest.xml中具有ACCESS_COARSE_LOCATION
或ACCESS_FINE_LOCATION
權限
根據我的建議,代碼如下所示:
LocationManager mlocManager =
(LocationManager)getSystemService(Context.LOCATION_SERVICE);
LocationListener mlocListener = new MyLocationListener();
mlocManager.requestLocationUpdates( LocationManager.GPS_PROVIDER, 0, 0, mlocListener);
資源: http : //developer.android.com/reference/android/location/LocationManager.html http://developer.android.com/reference/android/location/LocationProvider.html http://www.firstdroid.com/ 2010/04/29 / android-development-using-gps-get-current-location-2 /
更新:答案是,用於在getBearing()中計算的兩點太近了,因此得出的結果不准確。 要更正此問題,請手動獲取兩個GPS點,然后使用bearingTo()查看更准確的結果。
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