java版谷歌地图计算两经纬度坐标点的距离

public class GoogleMapHelper {

	private static double EARTH_RADIUS = 6378.137;	//地球半径
	//将用角度表现的角转换为近似相等的用弧度表现的角 Math.toRadians
	private static double rad(double d)
	{
	    return d * Math.PI / 180.0;
	}

	/**
	 * 谷歌地图盘算两个坐标点的距离
	 * @param lng1	经度1
	 * @param lat1	纬度1
	 * @param lng2	经度2
	 * @param lat2	纬度2
	 * @return 距离（千米）
	 */
	public static double getDistance(double lng1, double lat1, double lng2, double lat2)
	{
	    double radLat1 = Math.toRadians(lat1);
	    double radLat2 = Math.toRadians(lat2);
	    double a = radLat1 - radLat2;
	    double b = Math.toRadians(lng1) - Math.toRadians(lng2);
	    double s = 2 * Math.asin(Math.sqrt(Math.pow(Math.sin(a/2),2) + 
	     Math.cos(radLat1)*Math.cos(radLat2)*Math.pow(Math.sin(b/2),2)));
	    s = s * EARTH_RADIUS;
	    s = Math.round(s * 10000) / 10000;
	    return s;
	}
	
	public static void main(String[] args) {
		long b = System.currentTimeMillis();
		for(int i=0; i<1000000; i++){
			getDistance(116.403933,39.914147, 116.403237,39.927919);
		}
		System.out.println("耗时："+(System.currentTimeMillis()-b)+"毫秒"); //耗时：461毫秒
		double dist = getDistance(116.403933,39.914147, 116.403237,39.927919);
		System.out.println("两点相距：" + dist + "千米");	//两点相距：1.0千米

	}
}public class GoogleMapHelper {

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