经纬度转换、两点距离、坐标系（比较详细，各类转换）

 火星坐标系，百度坐标系，地球坐标系之间的转换

public class GEOUtil {

    private static double PI = Math.PI;
    private static double AXIS = 6378245.0;
    private static double OFFSET = 0.00669342162296594323;
    private static double X_PI = PI * 3000.0 / 180.0;

    /**
     * GCJ-02=>BD09 火星坐标系=>百度坐标系
     *
     * @param glat
     * @param glon
     * @return
     */
    public static double[] gcj2BD09(double glat, double glon) {
        double x = glon;
        double y = glat;
        double[] latlon = new double[2];
        double z = Math.sqrt(x * x + y * y) + 0.00002 * Math.sin(y * X_PI);
        double theta = Math.atan2(y, x) + 0.000003 * Math.cos(x * X_PI);
        latlon[0] = z * Math.sin(theta) + 0.006;
        latlon[1] = z * Math.cos(theta) + 0.0065;
        return latlon;
    }

    /**
     * BD09=>GCJ-02 百度坐标系=>火星坐标系
     *
     * @param glat
     * @param glon
     * @return
     */
    public static double[] bd092GCJ(double glat, double glon) {
        double x = glon - 0.0065;
        double y = glat - 0.006;
        double[] latlon = new double[2];
        double z = Math.sqrt(x * x + y * y) - 0.00002 * Math.sin(y * X_PI);
        double theta = Math.atan2(y, x) - 0.000003 * Math.cos(x * X_PI);
        latlon[0] = z * Math.sin(theta);
        latlon[1] = z * Math.cos(theta);
        return latlon;
    }

    /**
     * BD09=>WGS84 百度坐标系=>地球坐标系
     *
     * @param glat
     * @param glon
     * @return
     */
    public static double[] bd092WGS(double glat, double glon) {
        double[] latlon = bd092GCJ(glat, glon);
        return gcj2WGS(latlon[0], latlon[1]);
    }

    /**
     * WGS84=》BD09 地球坐标系=>百度坐标系
     *
     * @param wgLat
     * @param wgLon
     * @return
     */
    public static double[] wgs2BD09(double wgLat, double wgLon) {
        double[] latlon = wgs2GCJ(wgLat, wgLon);
        return gcj2BD09(latlon[0], latlon[1]);
    }

    /**
     * WGS84=》GCJ02 地球坐标系=>火星坐标系
     *
     * @param wgLat
     * @param wgLon
     * @return
     */
    public static double[] wgs2GCJ(double wgLat, double wgLon) {
        double[] latlon = new double[2];
        if (outOfChina(wgLat, wgLon)) {
            latlon[0] = wgLat;
            latlon[1] = wgLon;
            return latlon;
        }
        double[] deltaD = delta(wgLat, wgLon);
        latlon[0] = wgLat + deltaD[0];
        latlon[1] = wgLon + deltaD[1];
        return latlon;
    }

    /**
     * GCJ02=>WGS84 火星坐标系=>地球坐标系(粗略)
     *
     * @param glat
     * @param glon
     * @return
     */
    public static double[] gcj2WGS(double glat, double glon) {
        double[] latlon = new double[2];
        if (outOfChina(glat, glon)) {
            latlon[0] = glat;
            latlon[1] = glon;
            return latlon;
        }
        double[] deltaD = delta(glat, glon);
        latlon[0] = glat - deltaD[0];
        latlon[1] = glon - deltaD[1];
        return latlon;
    }

    /**
     * GCJ02=>WGS84 火星坐标系=>地球坐标系（精确）
     *
     * @param gcjLat
     * @param gcjLon
     * @return
     */
    public static double[] gcj2WGSExactly(double gcjLat, double gcjLon) {
        double initDelta = 0.01;
        double threshold = 0.000000001;
        double dLat = initDelta, dLon = initDelta;
        double mLat = gcjLat - dLat, mLon = gcjLon - dLon;
        double pLat = gcjLat + dLat, pLon = gcjLon + dLon;
        double wgsLat, wgsLon, i = 0;
        while (true) {
            wgsLat = (mLat + pLat) / 2;
            wgsLon = (mLon + pLon) / 2;
            double[] tmp = wgs2GCJ(wgsLat, wgsLon);
            dLat = tmp[0] - gcjLat;
            dLon = tmp[1] - gcjLon;
            if ((Math.abs(dLat) < threshold) && (Math.abs(dLon) < threshold)) {
                break;
            }

            if (dLat > 0) {
                pLat = wgsLat;
            } else {
                mLat = wgsLat;
            }
            if (dLon > 0) {
                pLon = wgsLon;
            } else {
                mLon = wgsLon;
            }

            if (++i > 10000) {
                break;
            }
        }
        double[] latlon = new double[2];
        latlon[0] = wgsLat;
        latlon[1] = wgsLon;
        return latlon;
    }

    /**
     * 计算两点距离
     *
     * @param latA
     * @param logA
     * @param latB
     * @param logB
     * @return 单位（米）
     */
    public static double distance(double latA, double logA, double latB,
                                  double logB) {
        int earthR = 6371000;
        double x = Math.cos(latA * Math.PI / 180)
                * Math.cos(latB * Math.PI / 180)
                * Math.cos((logA - logB) * Math.PI / 180);
        double y = Math.sin(latA * Math.PI / 180)
                * Math.sin(latB * Math.PI / 180);
        double s = x + y;
        if (s > 1) {
            s = 1;
        }
        if (s < -1) {
            s = -1;
        }
        double alpha = Math.acos(s);
        double distance = alpha * earthR;
        return distance;
    }

    public static double[] delta(double wgLat, double wgLon) {
        double[] latlng = new double[2];
        double dLat = transformLat(wgLon - 105.0, wgLat - 35.0);
        double dLon = transformLon(wgLon - 105.0, wgLat - 35.0);
        double radLat = wgLat / 180.0 * PI;
        double magic = Math.sin(radLat);
        magic = 1 - OFFSET * magic * magic;
        double sqrtMagic = Math.sqrt(magic);
        dLat = (dLat * 180.0)
                / ((AXIS * (1 - OFFSET)) / (magic * sqrtMagic) * PI);
        dLon = (dLon * 180.0) / (AXIS / sqrtMagic * Math.cos(radLat) * PI);
        latlng[0] = dLat;
        latlng[1] = dLon;
        return latlng;
    }

    public static boolean outOfChina(double lat, double lon) {
        if (lon < 72.004 || lon > 137.8347) {
            return true;
        }
        if (lat < 0.8293 || lat > 55.8271) {
            return true;
        }
        return false;
    }

    public static double transformLat(double x, double y) {
        double ret = -100.0 + 2.0 * x + 3.0 * y + 0.2 * y * y + 0.1 * x * y
                + 0.2 * Math.sqrt(Math.abs(x));
        ret += (20.0 * Math.sin(6.0 * x * PI) + 20.0 * Math.sin(2.0 * x * PI)) * 2.0 / 3.0;
        ret += (20.0 * Math.sin(y * PI) + 40.0 * Math.sin(y / 3.0 * PI)) * 2.0 / 3.0;
        ret += (160.0 * Math.sin(y / 12.0 * PI) + 320 * Math.sin(y * PI / 30.0)) * 2.0 / 3.0;
        return ret;
    }

    public static double transformLon(double x, double y) {
        double ret = 300.0 + x + 2.0 * y + 0.1 * x * x + 0.1 * x * y + 0.1
                * Math.sqrt(Math.abs(x));
        ret += (20.0 * Math.sin(6.0 * x * PI) + 20.0 * Math.sin(2.0 * x * PI)) * 2.0 / 3.0;
        ret += (20.0 * Math.sin(x * PI) + 40.0 * Math.sin(x / 3.0 * PI)) * 2.0 / 3.0;
        ret += (150.0 * Math.sin(x / 12.0 * PI) + 300.0 * Math.sin(x / 30.0
                * PI)) * 2.0 / 3.0;
        return ret;
    }

}