我正在开发一个应用程序，尝试获取用户的速度和行驶距离。我已经使用了Google Play服务位置类来获取速度，但它总是返回给我0.0值，并且不可靠。我想要实时准确的速度和行驶距离。
我在我的设备上安装了GPS速度表应用程序，非常完美，即使我在走路时也能给我速度。我想获得同样的结果。我困惑于如何获取速度，使用位置还是使用加速度计，或者是否有其他方法可以做到？
我的代码可在此链接中找到：
使用Google Maps Android API v2在Google Maps上绘制路线
我正在开发基于位置的纯定位应用程序，其中包括地图，速度和其他与位置相关的内容。
如果有任何人有任何想法，请帮助我解决速度和距离问题。
我曾经碰到过同样的问题，你可以使用位置策略代码来处理。
然后，在每次位置更新时，保存当前更新的时间。这样，你就会有之前和当前的位置，以及更新的时间。
然后，你可以计算这两个位置（旧的和新的）之间的距离，单位为米。
private static long calculateDistance(double lat1, double lng1, double lat2, double lng2) {
double dLat = Math.toRadians(lat2 - lat1);
double dLon = Math.toRadians(lng2 - lng1);
double a = Math.sin(dLat / 2) * Math.sin(dLat / 2)
+ Math.cos(Math.toRadians(lat1))
* Math.cos(Math.toRadians(lat2)) * Math.sin(dLon / 2)
* Math.sin(dLon / 2);
double c = 2 * Math.asin(Math.sqrt(a));
long distanceInMeters = Math.round(6371000 * c);
return distanceInMeters;
}
所以，你已经有了距离和时间差，我认为获取速度不是什么大问题。
当我使用Google Play位置API时，我也遇到了这个问题，希望这可以帮到你。
返回0是因为您的设备无法锁定GPS，或无法连接到GPS。
我尝试使用旧的联想设备获取速度，它返回0，因为它无法锁定GPS。
我尝试使用三星Galaxy Nexus，它返回我的速度（具有更好的GPS传感器）。
您手机中的GPS传感器可能不太好，或者您所处的区域GPS信号较弱，例如在房屋或建筑物内。
如果location.hasSpeed为false，则我计算速度，并使用location.getSpeed如果location.hasSpeed为true。
我还尝试使用活动识别来提高计算速度的准确性。
//Computation for speed
cur_time = System.currentTimeMillis() / 1000L;
if (location.hasSpeed()) {
loc_Speed = location.getSpeed();
//counter goes back to 0
count_OnFoot = 0;
Toast.makeText(getBaseContext(), "has speed", Toast.LENGTH_SHORT).show();
} else {
float[] result = new float[1];
location.distanceBetween(prev_latitude, prev_longitude,
loc_Latitude, loc_Longitude,
result);
float loc_distance = result[0];
//speed if location.getSpeed is null
loc_Speed = loc_distance/(cur_time - prev_time);
//if activity type is on foot
//estimate AVE_RUNNING_SPEED = 3m/s
if (act_ActivityType.equals(ActivityRecognitionService.ACT_ON_FOOT) && loc_Speed > AVE_RUNNING_SPEED) {
count_OnFoot++;
if (count_OnFoot < 2) {
Toast.makeText(getBaseContext(), "on foot and 1st > 3m/s", Toast.LENGTH_SHORT).show();
/*
* Since the speed is more than
* the average running speed,we will
* assume that its not a correct value
* and a fault that it detected a very far signal from the previous one.
* (This happens sometimes)
* We will assign the previous speed
* as its current speed.
*/
loc_Speed = prev_Speed;
} else {
Toast.makeText(getBaseContext(), "on foot and TWICE > 3m/s in a row", Toast.LENGTH_SHORT).show();
/*
* Do Nothing
* loc_Speed is equals the computed speed
* if it happens twice or more in a row.
* We will assume that its running fast.
*/
}
}else {
count_OnFoot = 0;
}
}
prev_Speed = loc_Speed;
/*
* If more than 60% sure that its still.
*
* Let your speed and direction be 0
* latitude and longitude should not change
*/
if (act_ActivityType.equals(ActivityRecognitionService.ACT_STILL)) {
loc_Speed = 0;
loc_Direction = 0;
if (prev_latitude != 0 && prev_longitude != 0) {
loc_Latitude = prev_latitude;
loc_Longitude = prev_longitude;
}
}
prev_time = cur_time;
prev_latitude = loc_Latitude;
prev_longitude = loc_Longitude;
//Note: My activity type will return on foot or still if its more than 60% sure
//otherwise null.
public static double getSpeed(Location currentLocation, Location oldLocation)
{
double newLat = currentLocation.getLatitude();
double newLon = currentLocation.getLongitude();
double oldLat = oldLocation.getLatitude();
double oldLon = oldLocation.getLongitude();
if(currentLocation.hasSpeed()){
return currentLocation.getSpeed();
} else {
double radius = 6371000;
double dLat = Math.toRadians(newLat-oldLat);
double dLon = Math.toRadians(newLon-oldLon);
double a = Math.sin(dLat/2) * Math.sin(dLat/2) +
Math.cos(Math.toRadians(newLat)) * Math.cos(Math.toRadians(oldLat)) *
Math.sin(dLon/2) * Math.sin(dLon/2);
double c = 2 * Math.asin(Math.sqrt(a));
double distance = Math.round(radius * c);
double timeDifferent = currentLocation.getTime() - oldLocation.getTime();
return distance/timeDifferent;
}
}
double curTime= 0;
double oldLat = 0.0;
double oldLon = 0.0;
现在转到您的onLocationChanged方法，并在其中调用此方法，
getspeed(location);
现在让我们实现 getSpeed 方法
private void getspeed(Location location){
double newTime= System.currentTimeMillis();
double newLat = location.getLatitude();
double newLon = location.getLongitude();
if(location.hasSpeed()){
float speed = location.getSpeed();
Toast.makeText(getApplication(),"SPEED : "+String.valueOf(speed)+"m/s",Toast.LENGTH_SHORT).show();
} else {
double distance = calculationBydistance(newLat,newLon,oldLat,oldLon);
double timeDifferent = newTime - curTime;
double speed = distance/timeDifferent;
curTime = newTime;
oldLat = newLat;
oldLon = newLon;
Toast.makeText(getApplication(),"SPEED 2 : "+String.valueOf(speed)+"m/s",Toast.LENGTH_SHORT).show();
}
}
好的，我们已经完成了这个步骤，现在需要实现calculationBydistance方法。
public double calculationBydistance(double lat1, double lon1, double lat2, double lon2){
double radius = EARTH_RADIUS;
double dLat = Math.toRadians(lat2-lat1);
double dLon = Math.toRadians(lon2-lon1);
double a = Math.sin(dLat/2) * Math.sin(dLat/2) +
Math.cos(Math.toRadians(lat1)) * Math.cos(Math.toRadians(lat2)) *
Math.sin(dLon/2) * Math.sin(dLon/2);
double c = 2 * Math.asin(Math.sqrt(a));
return radius * c;
}
location.distanceTo(Location)来获取距离？ - Renan Bandeira