//正算
public double[] gaussBLtoXY(double longitude,double latitude) {
    int ProjNo = 0;

    // 带宽
    int ZoneWide = 6;

    double longitude1, latitude1, longitude0, X0, Y0, xval, yval;
    double a, f, e2, ee, NN, T, C, A, M, iPI;

    // 3.1415926535898/180.0;
    iPI = 0.0174532925199433;

    // 54年北京坐标系参数
    a = 6378245.0;
    f = 1.0 / 298.3;

    // 80年西安坐标系参数
    // a=6378140.0;
    // f=1/298.257;

    ProjNo = (int) (longitude / ZoneWide);
    longitude0 = ProjNo * ZoneWide + ZoneWide / 2;
    longitude0 = longitude0 * iPI;

    // 经度转换为弧度
    longitude1 = longitude * iPI;

    // 纬度转换为弧度
    latitude1 = latitude * iPI;

    e2 = 2 * f - f * f;
    ee = e2 * (1.0 - e2);
    NN = a / Math.sqrt(1.0 - e2 * Math.sin(latitude1) * Math.sin(latitude1));
    T = Math.tan(latitude1) * Math.tan(latitude1);
    C = ee * Math.cos(latitude1) * Math.cos(latitude1);
    A = (longitude1 - longitude0) * Math.cos(latitude1);
    M = a * ((1 - e2 / 4 - 3 * e2 * e2 / 64 - 5 * e2 * e2 * e2 / 256) * latitude1 - (3 * e2 / 8 + 3 * e2 * e2 / 32 + 45 * e2 * e2 * e2 / 1024) * Math.sin(2 * latitude1) + (15 * e2 * e2 / 256 + 45 * e2 * e2 * e2 / 1024) * Math.sin(4 * latitude1) - (35 * e2 * e2 * e2 / 3072) * Math.sin(6 * latitude1));
    xval = NN * (A + (1 - T + C) * A * A * A / 6 + (5 - 18 * T + T * T + 72 * C - 58 * ee) * A * A * A * A * A / 120);
    yval = M + NN * Math.tan(latitude1) * (A * A / 2 + (5 - T + 9 * C + 4 * C * C) * A * A * A * A / 24 + (61 - 58 * T + T * T + 600 * C - 330 * ee) * A * A * A * A * A * A / 720);
    X0 = 1000000 * (ProjNo + 1) + 500000;
    Y0 = 0;
    xval = xval + X0;
    yval = yval + Y0;
    return new double[] { xval, yval };
}
//反算
public double[] gaussXYtoBL(double X,double Y) {
    int ProjNo;
    int ZoneWide; // //带宽
    double[] output = new double[2];
    double longitude1, latitude1, longitude0, X0, Y0, xval, yval;// latitude0,
    double e1, e2, f, a, ee, NN, T, C, M, D, R, u, fai, iPI;
    iPI = 0.0174532925199433; // //3.1415926535898/180.0;
    a = 6378245.0; f = 1.0/298.3; //54年北京坐标系参数
    //a = 6378140.0;
    //f = 1 / 298.257; // 80年西安坐标系参数
    // 54年北京坐标系参数

    ZoneWide = 6; // //6度带宽
    ProjNo = (int) (X / 1000000); // 查找带号
    longitude0 = (ProjNo - 1) * ZoneWide + ZoneWide / 2;
    longitude0 = longitude0 * iPI; // 中央经线

    X0 = ProjNo * 1000000 + 500000;
    Y0 = 0;
    xval = X - X0;
    yval = Y - Y0; // 带内大地坐标
    e2 = 2 * f - f * f;
    e1 = (1.0 - Math.sqrt(1 - e2)) / (1.0 + Math.sqrt(1 - e2));
    ee = e2 / (1 - e2);
    M = yval;
    u = M / (a * (1 - e2 / 4 - 3 * e2 * e2 / 64 - 5 * e2 * e2 * e2 / 256));
    fai = u + (3 * e1 / 2 - 27 * e1 * e1 * e1 / 32) * Math.sin(2 * u) + (21 * e1 * e1 / 16 - 55 * e1 * e1 * e1 * e1 / 32) * Math.sin(4 * u) + (151 * e1 * e1 * e1 / 96) * Math.sin(6 * u) + (1097 * e1 * e1 * e1 * e1 / 512) * Math.sin(8 * u);
    C = ee * Math.cos(fai) * Math.cos(fai);
    T = Math.tan(fai) * Math.tan(fai);
    NN = a / Math.sqrt(1.0 - e2 * Math.sin(fai) * Math.sin(fai));
    R = a * (1 - e2) / Math.sqrt((1 - e2 * Math.sin(fai) * Math.sin(fai)) * (1 - e2 * Math.sin(fai) * Math.sin(fai)) * (1 - e2 * Math.sin(fai) * Math.sin(fai)));
    D = xval / NN;
    // 计算经度(Longitude) 纬度(Latitude)
    longitude1 = longitude0 + (D - (1 + 2 * T + C) * D * D * D / 6 + (5 - 2 * C + 28 * T - 3 * C * C + 8 * ee + 24 * T * T) * D * D * D * D * D / 120) / Math.cos(fai);
    latitude1 = fai - (NN * Math.tan(fai) / R) * (D * D / 2 - (5 + 3 * T + 10 * C - 4 * C * C - 9 * ee) * D * D * D * D / 24 + (61 + 90 * T + 298 * C + 45 * T * T - 256 * ee - 3 * C * C) * D * D * D * D * D * D / 720);
    // 转换为度 DD
    output[0] = longitude1 / iPI;
    output[1] = latitude1 / iPI;
    return output;
}