java实现北斗转GPS坐标

要将北斗坐标转换为GPS坐标，需要进行如下步骤：

1. 将北斗坐标系转换为地球坐标系；
2. 将地球坐标系转换为经纬度坐标系。

下面是Java代码实现：

public class BeidouToGPS {
    private static final double X_PI = 3.14159265358979324 * 3000.0 / 180.0;
    private static final double A = 6378245.0;
    private static final double EE = 0.00669342162296594323;
    
    public static double[] bd09ToWGS84(double bd_lon, double bd_lat) {
        double[] gcj = bd09ToGCJ02(bd_lon, bd_lat);
        return gcjToWGS84(gcj[0], gcj[1]);
    }
    
    public static double[] bd09ToGCJ02(double bd_lon, double bd_lat) {
        double x = bd_lon - 0.0065;
        double y = bd_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_lon, gg_lat};
    }
    
    public static double[] gcjToWGS84(double lon, double lat) {
        if (outOfChina(lon, lat)) {
            return new double[]{lon, lat};
        }
        double dLat = transformLat(lon - 105.0, lat - 35.0);
        double dLon = transformLon(lon - 105.0, lat - 35.0);
        double radLat = lat / 180.0 * Math.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) * Math.PI);
        dLon = (dLon * 180.0) / (A / sqrtMagic * Math.cos(radLat) * Math.PI);
        double mgLat = lat + dLat;
        double mgLon = lon + dLon;
        return new double[]{lon * 2 - mgLon, lat * 2 - mgLat};
    }
    
    private static boolean outOfChina(double lon, double lat) {
        return lon < 72.004 || lon > 137.8347 || lat < 0.8293 || lat > 55.8271;
    }
    
    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 * Math.PI) + 20.0 * Math.sin(2.0 * x * Math.PI)) * 2.0 / 3.0;
        ret += (20.0 * Math.sin(y * Math.PI) + 40.0 * Math.sin(y / 3.0 * Math.PI)) * 2.0 / 3.0;
        ret += (160.0 * Math.sin(y / 12.0 * Math.PI) + 320 * Math.sin(y * Math.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 * Math.PI) + 20.0 * Math.sin(2.0 * x * Math.PI)) * 2.0 / 3.0;
        ret += (20.0 * Math.sin(x * Math.PI) + 40.0 * Math.sin(x / 3.0 * Math.PI)) * 2.0 / 3.0;
        ret += (150.0 * Math.sin(x / 12.0 * Math.PI) + 300.0 * Math.sin(x / 30.0 * Math.PI)) * 2.0 / 3.0;
        return ret;
    }
}

其中，bd09ToWGS84方法用于将北斗坐标系转换为经纬度坐标系，bd09ToGCJ02方法用于将北斗坐标系转换为地球坐标系，gcjToWGS84方法用于将地球坐标系转换为经纬度坐标系。outOfChina方法用于判断经纬度坐标是否在中国境内，transformLat和transformLon方法用于进行坐标转换。调用bd09ToWGS84方法即可完成北斗坐标系到GPS坐标系的转换。