java - 在Android中计算距离

Question

我想用它来计算我当前位置和标记之间的距离

private double distance(double lat1, double lon1, double lat2, double lon2) {
  double theta = lon1 - lon2;
  double dist = Math.sin(deg2rad(lat1)) * Math.sin(deg2rad(lat2)) +   Math.cos(deg2rad(lat1)) * Math.cos(deg2rad(lat2)) * Math.cos(deg2rad(theta));
  dist = Math.acos(dist);
  dist = rad2deg(dist);
  dist = dist * 60 * 1.1515;
   return (dist);
}

  private double deg2rad(double deg) {
  return (deg * Math.PI / 180.0);
}
private double rad2deg(double rad) {
  return (rad * 180.0 / Math.PI);
}

我可以通过将其放入 onLocationChanged 方法来定期更新它吗？我知道这proximity将是一个更优雅的解决方案，但我遇到了问题，而且我的日程安排很紧。

Answer 1

看看计算纬度/经度点之间的距离、方位角等。

private double distance(double lat1, double lon1, double lat2, double lon2) {
    int R = 6371; //km
    double dLat = deg2rad(lat1 - lat2);
    double dLon = deg2rad(lon1 - lon2);
    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)); 
    return c * R;
}

Answer 2

试试这个代码来计算距离。

    public double CalculationByDistance(GeoPoint StartP, GeoPoint EndP) {  
  double lat1 = StartP.getLatitudeE6()/1E6;  
  double lat2 = EndP.getLatitudeE6()/1E6;  
  double lon1 = StartP.getLongitudeE6()/1E6;  
  double lon2 = EndP.getLongitudeE6()/1E6;  
  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;  
 }