GPS地图坐标转百度地图坐标

真实标准坐标即我们获取到的坐标，真实坐标经经过国家测绘局进行加密后形成火星坐标（WGS-84），百度地图坐标，是在火星坐标的基础上再进行一次加密，形成了百度地图上的坐标，因此，直接将标准地球坐标显示在百度地图上是会有几百米的偏差的。按照此原理，标准GPS坐标经过两步的转换可得到百度坐标，百度在线的API可以实现，但有些项目环境是不需要百度在线API的，所以需要我们自己转换。
后台转换算法如下：

/**
 * pi: 圆周率。
 a: 卫星椭球坐标投影到平面地图坐标系的投影因子。
 ee: 椭球的偏心率。
 x_pi: 圆周率转换量。
 transformLat(lat, lon): 输入：横纵坐标，输出：转换后的横坐标。
 transformLon(lat, lon): 输入：横纵坐标，输出：转换后的纵坐标。
 wgs2gcj(lat, lon): WGS坐标转换为GCJ坐标。
 gcj2bd(lat, lon): GCJ坐标转换为百度坐标。
 */
public class MapTest {
    static double pi = 3.14159265358979324;
    static double a = 6378245.0;
    static double ee = 0.00669342162296594323;
    public final static double x_pi = 3.14159265358979324 * 3000.0 / 180.0;

    public double[] wgs2bd(double lat, double lon) {
        double[] wgs2gcj = wgs2gcj(lat, lon);
        double[] gcj2bd = gcj2bd(wgs2gcj[0], wgs2gcj[1]);
        return gcj2bd;
    }

    public static double[] gcj2bd(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 double[]{bd_lat, bd_lon};
    }

    public static double[] bd2gcj(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 gg_lon = z * Math.cos(theta);
        double gg_lat = z * Math.sin(theta);
        return new double[]{gg_lat, gg_lon};
    }

    public static double[] wgs2gcj(double lat, double 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;
        double[] loc = {mgLat, mgLon};
        return loc;
    }

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

    private static double transformLon(double lat, double lon) {
        double ret = 300.0 + lat + 2.0 * lon + 0.1 * lat * lat + 0.1 * lat * lon + 0.1 * Math.sqrt(Math.abs(lat));
        ret += (20.0 * Math.sin(6.0 * lat * pi) + 20.0 * Math.sin(2.0 * lat * pi)) * 2.0 / 3.0;
        ret += (20.0 * Math.sin(lat * pi) + 40.0 * Math.sin(lat / 3.0 * pi)) * 2.0 / 3.0;
        ret += (150.0 * Math.sin(lat / 12.0 * pi) + 300.0 * Math.sin(lat / 30.0 * pi)) * 2.0 / 3.0;
        return ret;
    }

}

public static void main(String args[]) {
    MapTest mapTest = new MapTest();
    double a[] = mapTest.wgs2bd(23.005633,113.073192);
    for (int i = 0; i < a.length; i++) {
        System.out.println(a[i]);
    }

}public static void main(String args[]) {
    MapTest mapTest = new MapTest();
    double a[] = mapTest.wgs2bd(23.005633,113.073192);
    for (int i = 0; i < a.length; i++) {
        System.out.println(a[i]);
    }

}

在线API的转换：