WGS84(GPS)、火星坐标系（GCJ02）、百度地图（BD09）坐标系转换Java代码

在做基于百度地图、高德地图等电子地图做为地图服务的二次开发时，通常需要将具有WGS84等坐标的矢量数据（如行政区划、地名、河流、道路等GIS地理空间数据）添加到地图上面。

然而，在线地图大多使用的是火星坐标系，需要事先将矢量数据转为火星坐标系。本文代码针对WGS84(GPS)、火星坐标系（GCJ02）、百度地图（BD09）坐标系之间互相转换。

public class GpsUtils {
    private static final double x_pi = 3.1415926535897932384626433832795028841971 * 3000.0 / 180.0;
    private static final double pi = 3.1415926535897932384626433832795028841971;
    private static final double a = 6378245.0;
    private static final double ee = 0.00669342162296594323;

    /**
     * 84 to 火星坐标系 (GCJ-02) World Geodetic System ==> Mars Geodetic System
     *
     * @param lat 纬度
     * @param lon 经度
     */
    public static Gps wgs84ToGcj02(double lat, double lon) {
        if (outOfChina(lat, lon)) {
            return new Gps(lat, lon);
        }
        double dLat = transformLat(lon - 105.0, lat - 35.0);
        double dLon = transformLon(lon - 105.0, lat - 35.0);
        double radLat = lat / 180.0 * pi;
        double magic = Math.sin(radLat);
        magic = 1 - ee * magic * magic;
        double sqrtMagic = Math.sqrt(magic);
        dLat = (dLat * 180.0) / ((a * (1 - ee)) / (magic * sqrtMagic) * pi);
        dLon = (dLon * 180.0) / (a / sqrtMagic * Math.cos(radLat) * pi);
        double mgLat = lat + dLat;
        double mgLon = lon + dLon;
        return new Gps(mgLat, mgLon);
    }

    /**
     * WGS84 To 百度BD09
     *
     * @param lat 纬度
     * @param lon 经度
     * @return
     */
    public static Gps wgs84ToBd09(double lat, double lon) {
        var gps = wgs84ToGcj02(lat, lon);
        return gcj02ToBd09(gps.getLat(), gps.getLon());
    }

    /**
     * 火星坐标系 (GCJ-02) to 84
     *
     * @param lat 纬度
     * @param lon 经度
     * @return
     */
    public static Gps gcj02ToGps84(double lat, double lon) {
        Gps gps = transform(lat, lon);
        double longtitude = lon * 2 - gps.getLon();
        double latitude = lat * 2 - gps.getLat();
        return new Gps(latitude, longtitude);
    }

    /**
     * 火星坐标系 (GCJ-02) 与百度坐标系 (BD-09) 的转换算法 将 GCJ-02 坐标转换成 BD-09 坐标
     *
     * @param lat 纬度
     * @param lon 经度
     */
    public static Gps gcj02ToBd09(double lat, double lon) {
        double x = lon, y = lat;
        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);
        double bd_lon = z * Math.cos(theta) + 0.0065;
        double bd_lat = z * Math.sin(theta) + 0.006;
        return new Gps(bd_lat, bd_lon);
    }

    /**
     * 火星坐标系 (GCJ-02) 与百度坐标系 (BD-09) 的转换算法,将 BD-09 坐标转换成GCJ-02 坐标
     *
     * @param lat 纬度
     * @param lon 经度
     * @return
     */
    public static Gps bd09ToGcj02(double lat, double lon) {
        double x = lon - 0.0065, y = lat - 0.006;
        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);
        double ggLon = z * Math.cos(theta);
        double ggLat = z * Math.sin(theta);
        return new Gps(ggLat, ggLon);
    }

    /**
     * (BD-09)-->84
     *
     * @param lat 纬度
     * @param lon 经度
     * @return
     */
    public static Gps bd09ToWgs84(double lat, double lon) {

        Gps gcj02 = bd09ToGcj02(lat, lon);
        Gps map84 = gcj02ToGps84(gcj02.getLat(),
                gcj02.getLon());
        return map84;

    }

    /**
     * 将wgs84转换到指定坐标系
     *
     * @param coordType 0=wgs84,1=百度坐标系,2=高德,腾讯，火星坐标系
     * @param lat       纬度
     * @param lon       经度
     * @return 转换后的坐标，为null表示转换失败
     */
    public static Gps wgs84To(int coordType, double lat, double lon) {
        switch (coordType) {
            case 1: {
                return wgs84ToBd09(lat, lon);
            }
            case 2: {
                return wgs84ToGcj02(lat, lon);
            }
            default:
                return null;
        }
    }


    private static Gps transform(double lat, double lon) {
        if (outOfChina(lat, lon)) {
            return new Gps(lat, lon);
        }
        double dLat = transformLat(lon - 105.0, lat - 35.0);
        double dLon = transformLon(lon - 105.0, lat - 35.0);
        double radLat = lat / 180.0 * pi;
        double magic = Math.sin(radLat);
        magic = 1 - ee * magic * magic;
        double sqrtMagic = Math.sqrt(magic);
        dLat = (dLat * 180.0) / ((a * (1 - ee)) / (magic * sqrtMagic) * pi);
        dLon = (dLon * 180.0) / (a / sqrtMagic * Math.cos(radLat) * pi);
        double mgLat = lat + dLat;
        double mgLon = lon + dLon;
        return new Gps(mgLat, mgLon);
    }

    private 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;
    }


    private 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;
    }
}