地图系的转换

关于地图中，各个地图系相互转换的方法，此处是复制别人的，仅作收藏。

在转换过程中一度出现精度偏差的情况，这里要注意 pi 的取值，原博客没有注意此问题，在应用的过程中纠结了很久。

    /** 
     * 各地图API坐标系统比较与转换; 
     * WGS84坐标系：即地球坐标系，国际上通用的坐标系。设备一般包含GPS芯片或者北斗芯片获取的经纬度为WGS84地理坐标系, 
     * 谷歌地图采用的是WGS84地理坐标系（中国范围除外）; 
     * GCJ02坐标系：即火星坐标系，是由中国国家测绘局制订的地理信息系统的坐标系统。由WGS84坐标系经加密后的坐标系。 
     * 谷歌中国地图和搜搜中国地图采用的是GCJ02地理坐标系; BD09坐标系：即百度坐标系，GCJ02坐标系经加密后的坐标系; 
     * 搜狗坐标系、图吧坐标系等，估计也是在GCJ02基础上加密而成的。 chenhua 
     */  
    public class PositionUtil {  
          
        public static final String BAIDU_LBS_TYPE = "bd09ll";  
          
        public static double pi = 3.1415926535897932384626 * 3000.0 / 180.0;  //此处注意 pi = 派 * 3000 / 180 ;
        public static double a = 6378245.0;  
        public static double ee = 0.00669342162296594323;  
      
        /** 
         * 84 to 火星坐标系 (GCJ-02) World Geodetic System ==> Mars Geodetic System 
         *  
         * @param lat 
         * @param lon 
         * @return 
         */  
        public static Gps gps84_To_Gcj02(double lat, double lon) {  
            if (outOfChina(lat, lon)) {  
                return null;  
            }  
            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);  
        }  
      
        /** 
         * * 火星坐标系 (GCJ-02) to 84 * * @param lon * @param lat * @return 
         * */  
        public static Gps gcj_To_Gps84(double lat, double lon) {  
            Gps gps = transform(lat, lon);  
            double lontitude = lon * 2 - gps.getWgLon();  
            double latitude = lat * 2 - gps.getWgLat();  
            return new Gps(latitude, lontitude);  
        }  
      
        /** 
         * 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 gg_lat 
         * @param gg_lon 
         */  
        public static Gps gcj02_To_Bd09(double gg_lat, double gg_lon) {  
            double x = gg_lon, y = gg_lat;  
            double z = Math.sqrt(x * x + y * y) + 0.00002 * Math.sin(y * pi);  
            double theta = Math.atan2(y, x) + 0.000003 * Math.cos(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 
         * bd_lat * @param bd_lon * @return 
         */  
        public static Gps bd09_To_Gcj02(double bd_lat, double bd_lon) {  
            double x = bd_lon - 0.0065, y = bd_lat - 0.006;  
            double z = Math.sqrt(x * x + y * y) - 0.00002 * Math.sin(y * pi);  
            double theta = Math.atan2(y, x) - 0.000003 * Math.cos(x * pi);  
            double gg_lon = z * Math.cos(theta);  
            double gg_lat = z * Math.sin(theta);  
            return new Gps(gg_lat, gg_lon);  
        }  
      
        /** 
         * (BD-09)-->84 
         * @param bd_lat 
         * @param bd_lon 
         * @return 
         */  
        public static Gps bd09_To_Gps84(double bd_lat, double bd_lon) {  
      
            Gps gcj02 = PositionUtil.bd09_To_Gcj02(bd_lat, bd_lon);  
            Gps map84 = PositionUtil.gcj_To_Gps84(gcj02.getWgLat(),  
                    gcj02.getWgLon());  
            return map84;  
      
        }  
      
        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 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);  
        }  
      
        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;  
        }  
      
        public static void main(String[] args) {  
      
            // 北斗芯片获取的经纬度为WGS84地理坐标 31.426896,119.496145  
            Gps gps = new Gps(31.426896, 119.496145);  
            System.out.println("gps :" + gps);  
            Gps gcj = gps84_To_Gcj02(gps.getWgLat(), gps.getWgLon());  
            System.out.println("gcj :" + gcj);  
            Gps star = gcj_To_Gps84(gcj.getWgLat(), gcj.getWgLon());  
            System.out.println("star:" + star);  
            Gps bd = gcj02_To_Bd09(gcj.getWgLat(), gcj.getWgLon());  
            System.out.println("bd  :" + bd);  
            Gps gcj2 = bd09_To_Gcj02(bd.getWgLat(), bd.getWgLon());  
            System.out.println("gcj :" + gcj2);  
        }  
    }  

public class Gps {
    private double wgLat;
    private double wgLon;
    public Gps(double wgLat, double wgLon) {
        setWgLat(wgLat);
        setWgLon(wgLon);
    }
    public double getWgLat() {
        return wgLat;
    }
    public void setWgLat(double wgLat) {
        this.wgLat = wgLat;
    }
    public double getWgLon() {
        return wgLon;
    }
    public void setWgLon(double wgLon) {
        this.wgLon = wgLon;
    }
    @Override
    public String toString() {
        return wgLat + "," + wgLon;
    }
}