为什么getSpeed（）在android上总是返回0
我需要从gps获取速度和航向。但是，我从为什么getSpeed（）在android上总是返回0,android,gps,performance,location,Android,Gps,Performance,Location,我需要从gps获取速度和航向。但是，我从location.getSpeed（）获得的唯一数字是0，有时不可用。我的代码： String provider = initLocManager(); if (provider == null) return false; LocationListener locListener = new LocationListener() { public void onLocationChanged
location.getSpeed（） String provider = initLocManager();
if (provider == null)
return false;
LocationListener locListener = new LocationListener() {
public void onLocationChanged(Location location) {
updateWithNewLocation(location, interval, startId);
Log.i(getString(R.string.logging_tag), "speed =" + location.getSpeed());
}
public void onProviderDisabled(String provider){
updateWithNewLocation(null, interval, startId);
}
public void onProviderEnabled(String provider) {}
public void onStatusChanged(String provider, int status, Bundle extras) {}
};
_locManager.requestLocationUpdates(provider, interval, DEFAULT_GPS_MIN_DISTANCE, locListener);
private String initLocManager() {
String context = Context.LOCATION_SERVICE;
_locManager = (LocationManager) getSystemService(context);
Criteria criteria = new Criteria();
criteria.setAccuracy(Criteria.ACCURACY_FINE);
criteria.setAltitudeRequired(false);
criteria.setBearingRequired(true);
criteria.setSpeedRequired(true);
criteria.setCostAllowed(true);
//criteria.setPowerRequirement(Criteria.POWER_LOW);
String provider = _locManager.getBestProvider(criteria, true);
if (provider == null || provider.equals("")) {
displayGPSNotEnabledWarning(this);
return null;
}
return provider;
}
Speed = distance / time
(currentGPSPoint - lastGPSPoint) / (time between GPS points)
(sqrt((currentGPSPointX - lastGPSPointX)^2) + (currentGPSPointY - lastGPSPointY)^2)) / (time between GPS points)
requestLocationUpdates（）getSpeed（）但这可能会有所帮助：：）在一个球形行星上，应该用以下公式计算距离：
private static Double distance(Location one, Location two) {
int R = 6371000;
Double dLat = toRad(two.getLatitude() - one.getLatitude());
Double dLon = toRad(two.getLongitude() - one.getLongitude());
Double lat1 = toRad(one.getLatitude());
Double lat2 = toRad(two.getLatitude());
Double a = Math.sin(dLat / 2) * Math.sin(dLat / 2)
+ Math.sin(dLon / 2) * Math.sin(dLon / 2) * Math.cos(lat1) * Math.cos(lat2);
Double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
Double d = R * c;
return d;
}
private static double toRad(Double d) {
return d * Math.PI / 180;
}
getspeed（）工作正常。你不必用距离公式来计算。它已经存在于getspeed中，只要有纬度和经度，getspeed中就会有速度。我以前也遇到过这个问题， 我希望这能有所帮助 它返回0，因为您的设备无法锁定GPS或无法连接到GPS 我试着用一台旧的联想设备获得速度，但它返回0，因为它无法锁定gps 我试着使用三星galaxy nexus，它恢复了我的速度（有更好的GPS传感器）
您手机中的GPS传感器可能不好，或者您所在的区域GPS信号较弱，例如在房子或建筑物内。我的自定义位置侦听器用于手动获取速度，如果有速度，则按位置对象获取速度
new LocationListener() {
private Location mLastLocation;
@Override
public void onLocationChanged(Location pCurrentLocation) {
//calcul manually speed
double speed = 0;
if (this.mLastLocation != null)
speed = Math.sqrt(
Math.pow(pCurrentLocation.getLongitude() - mLastLocation.getLongitude(), 2)
+ Math.pow(pCurrentLocation.getLatitude() - mLastLocation.getLatitude(), 2)
) / (pCurrentLocation.getTime() - this.mLastLocation.getTime());
//if there is speed from location
if (pCurrentLocation.hasSpeed())
//get location speed
speed = pCurrentLocation.getSpeed();
this.mLastLocation = pCurrentLocation;
////////////
//DO WHAT YOU WANT WITH speed VARIABLE
////////////
}
@Override
public void onStatusChanged(String s, int i, Bundle bundle) {
}
@Override
public void onProviderEnabled(String s) {
}
@Override
public void onProviderDisabled(String s) {
}
};
我基本上计算瞬时速度，然后使用setSpeed（）方法将其添加到位置。它非常准确，因为我在车内比较了它，在车内我可以检查测速仪
private double calculateInstantaneousSpeed(Location location) {
double insSpeed = 0;
if (y1 == null && x1 <= -1) {
//mark the location y1 at time x1
y1 = location;
x1 = duration.getDurationAsSeconds();
} else {
//mark the location y2 at time x2
y2 = location;
x2 = duration.getDurationAsSeconds();
//calculate the slope of the curve (instantaneous speed)
dy = y1.distanceTo(y2);
dx = x2 - x1;
insSpeed = dy / dx;
y1 = y2;
x1 = x2;
}
Singleton.getInstance().instantaneousSpeedSamples.add(insSpeed);
//System.out.println("Instantaneous Speed m/s: "+insSpeed);
return insSpeed;
}
private double calculateinnstantaneousspeed（位置）{
双insSpeed=0；
如果（y1==null&&x1getSpeed（）方法实际上工作得很好，但是您必须使用高请求间隔，比如1秒，并且需要高精度，首先我要做的是3秒间隔，优先级和功率平衡精度，我一直得到0值，直到我像我说的那样更改它。我使用的是融合位置提供程序api
public class Main3Activity extends AppCompatActivity {
private FusedLocationProviderClient mFusedLocationClient;
private int speed;
private double lat;
private double lng;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main2);
mFusedLocationClient = LocationServices.getFusedLocationProviderClient(this);
}
@Override
protected void onResume() {
super.onResume();
if(!runtime_permissions()) {
requestLocations();
}
}
@Override
protected void onPause() {
super.onPause();
//stop location updates when Activity is no longer active
if (mFusedLocationClient != null) {
mFusedLocationClient.removeLocationUpdates(mLocationCallback);
}
}
@SuppressLint("MissingPermission")
private void requestLocations(){
LocationRequest mLocationRequest = new LocationRequest();
mLocationRequest.setInterval(1000);;
mLocationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
mFusedLocationClient.requestLocationUpdates(mLocationRequest, mLocationCallback, Looper.myLooper());
}
LocationCallback mLocationCallback = new LocationCallback() {
@Override
public void onLocationResult(LocationResult locationResult) {
List<Location> locationList = locationResult.getLocations();
if (locationList.size() > 0) {
//The last location in the list is the newest
Location location = locationList.get(locationList.size() - 1);
lat = location.getLatitude();
lng = location.getLongitude();
//speed in km/h
speed = (int) ((location.getSpeed() * 3600) / 1000);
}
}
};
private boolean runtime_permissions() {
if(Build.VERSION.SDK_INT >= 23 && ContextCompat.checkSelfPermission(this,
Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED){
requestPermissions(new String[]{Manifest.permission.ACCESS_FINE_LOCATION},100);
return true;
}
return false;
}
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
if(requestCode == 100){
if( grantResults[0] == PackageManager.PERMISSION_GRANTED){
onResume();
}else{
runtime_permissions();
}
}
}
public class main3活动扩展了appcompative活动{
私有FusedLocationProviderClient mFusedLocationClient；
私人整数速度；
私人双lat；
私人双液化天然气；
@凌驾
创建时受保护的void（Bundle savedInstanceState）{
super.onCreate（savedInstanceState）；
setContentView（R.layout.activity_main2）；
mFusedLocationClient=LocationServices.getFusedLocationProviderClient（此）；
}
@凌驾
受保护的void onResume（）{
super.onResume（）；
如果（！运行时权限（））{
请求位置（）；
}
}
@凌驾
受保护的void onPause（）{
super.onPause（）；
//当活动不再处于活动状态时停止位置更新
if（mFusedLocationClient！=null）{
mFusedLocationClient.RemovelocationUpdate（mlLocationCallback）；
}
}
@SuppressLint（“丢失许可”）
私有void请求位置（）{
LocationRequest MLLocationRequest=新的LocationRequest（）；
mlLocationRequest.setInterval（1000）；；
mLocationRequest.setPriority（位置请求.优先级高精度）；
mFusedLocationClient.RequestLocationUpdate（mlLocationRequest、mlLocationCallback、Looper.myLooper（））；
}
LocationCallback mlLocationCallback=新LocationCallback（）{
@凌驾
public void onLocationResult（LocationResult LocationResult）{
List locationList=locationResult.getLocations（）；
如果（locationList.size（）>0）{
//列表中的最后一个位置是最新位置
Location=locationList.get（locationList.size（）-1）；
lat=位置。getLatitude（）；
lng=location.getLongitude（）；
//速度（单位：km/h）
速度=（int）（（location.getSpeed（）*3600）/1000）；
}
}
};
私有布尔运行时_权限（）{
如果（Build.VERSION.SDK_INT>=23&&ContextCompat.checkSelfPermission（此，
Manifest.permission.ACCESS\u FINE\u LOCATION）！=PackageManager.permission\u provided）{
requestPermissions（新字符串[]{Manifest.permission.ACCESS\u FINE\u LOCATION}，100）；
返回true；
}
返回false；
}
@凌驾
public void onRequestPermissionsResult（int-requestCode，@NonNull-String[]permissions，@NonNull-int[]grantResults）{
super.onRequestPermissionsResult（请求代码、权限、授权结果）；
if（requestCode==100）{
if（grantResults[0]==已授予PackageManager.权限）{
onResume（）；
}否则{
运行时权限（）；
}
}
}
}嘿，我也曾遭受同样的痛苦，但现在我已经解决了！
只需将该值乘以18/5，即可得出几乎准确的值
speed=location.getSpeed（）*18/5
同时指定间隔
为1000*2
和最快间隔
为1000*1
，以获得更高的准确性基于此处的其他建议，我将此代码与原因注释放在一起：
public static float getSpeedKmh(Location newLocation, Location previousLocation)
{
if(newLocation == null) throw new IllegalArgumentException("newLocation must not be null");
float speed = -1.0f;
if(newLocation.hasSpeed()) /* gps doppler speed at the current moment preferred */
{
speed = newLocation.getSpeed();
}else /* may be wifi or celltower based location: compute AVERAGE speed since last fix */
{
if(previousLocation == null) throw new IllegalArgumentException("Cannot compute speed without previousLocation (was null)");
if(previousLocation.getTime()==newLocation.getTime())
throw new IllegalArgumentException("Cannot compute speed from same time locations!"); /* diff by zero protection */
speed = newLocation.distanceTo(previousLocation) * 1000.0f /* time diff in millis so multiply by 1000 */
/ Math.abs(newLocation.getTime() - previousLocation.getTime()); /* Math abs: so you can even swap new and older location without effect */
}
return speed * 3.6f; /* m/s -> km/h */
}
public static float getSpeedKmh(Location newLocation, Location previousLocation)
{
if(newLocation == null) throw new IllegalArgumentException("newLocation must not be null");
float speed = -1.0f;
if(newLocation.hasSpeed()) /* gps doppler speed at the current moment preferred */
{
speed = newLocation.getSpeed();
}else /* may be wifi or celltower based location: compute AVERAGE speed since last fix */
{
if(previousLocation == null) throw new IllegalArgumentException("Cannot compute speed without previousLocation (was null)");
if(previousLocation.getTime()==newLocation.getTime())
throw new IllegalArgumentException("Cannot compute speed from same time locations!"); /* diff by zero protection */
speed = newLocation.distanceTo(previousLocation) * 1000.0f /* time diff in millis so multiply by 1000 */
/ Math.abs(newLocation.getTime() - previousLocation.getTime()); /* Math abs: so you can even swap new and older location without effect */
}
return speed * 3.6f; /* m/s -> km/h */
}