Java计算两个坐标之间的距离

背景：

在做项目的时候需要做手机端页面，需要计算两个坐标的距离，由于之前没有接触过这样的计算，于是就找上度娘帮忙，顺便记录下来

1、添加JTS依赖

JTS是加拿大的 Vivid Solutions公司做的一套开放源码的 Java API。它提供了一套空间数据操作的核心算法。为在兼容OGC标准的空间对象模型中进行基础的几何操作提供2D空间谓词API。

<!--空间地理坐标算法-->
<dependency>
	<groupId>com.vividsolutions</groupId>
	<artifactId>jts-core</artifactId>
	<version>1.14.0</version>
</dependency>

2、坐标系转换

WGS-84：是国际标准，GPS坐标（Google Earth使用、或者GPS模块）
GCJ-02：中国坐标偏移标准，Google Map、高德、腾讯使用
BD-09：百度坐标偏移标准，Baidu Map使用

/** * @Description 坐标标转换工具类 */
public class CoordinateUtil { 
 
	/** * pi */
	public final static double pi = 3.1415926535897932384626;
	/** * a */
	public final static double a = 6378245.0;
	/** * ee */
	public final static double ee = 0.00669342162296594323;
 
	/** * @Description WGS84 to 火星坐标系 (GCJ-02) * @param lon * @param lat * @return */
	public static double[] wgs84_To_Gcj02(double lon, double lat) { 
		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 double[] {  mgLon, mgLat };
	}
 
	/** * @Description 火星坐标系 (GCJ-02) to WGS84 * @param lon * @param lat * @return */
	public static double[] gcj02_To_Wgs84(double lon, double lat) { 
		double[] gps = transform(lat, lon);
		double lontitude = lon * 2 - gps[1];
		double latitude = lat * 2 - gps[0];
		return new double[] {  lontitude, latitude };
	}
 
	/** * @Description 火星坐标系 (GCJ-02) to 百度坐标系 (BD-09) * @param gg_lon * @param gg_lat * @return */
	public static double[] gcj02_To_Bd09(double gg_lon, double gg_lat) { 
		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 double[] {  bd_lon, bd_lat };
	}
 
	/** * @Description 百度坐标系 (BD-09) to 火星坐标系 (GCJ-02) * @param bd_lon * @param bd_lat * @return */
	public static double[] bd09_To_Gcj02(double bd_lon, double bd_lat) { 
		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 double[] {  gg_lon, gg_lat };
	}
	/** * @Description 百度坐标系 (BD-09) to WGS84 * @param bd_lat * @param bd_lon * @return */
	public static double[] bd09_To_Wgs84(double bd_lon,double bd_lat) { 
		double[] gcj02 = CoordinateUtil.bd09_To_Gcj02(bd_lon, bd_lat);
		double[] map84 = CoordinateUtil.gcj02_To_Wgs84(gcj02[0], gcj02[1]);
		return map84;
 
	}
 
	/** * @Description 判断是否在中国范围内 * @param lat * @param lon * @return */
	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;
	}
 
	/** * @Description transform * @param lat * @param lon * @return */
	private static double[] transform(double lat, double lon) { 
		if (outOfChina(lat, lon)) { 
			return new double[] {  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 double[] {  mgLat, mgLon };
	}
 
	/** * @Description transformLat * @param x * @param y * @return */
	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;
	}
 
	/** * @Description transformLon * @param x * @param y * @return */
	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;
	}
}

## 3、高斯投影转换

```java
/** * @Description WGS84 to 高斯投影(6度分带) * @param longitude 经度 * @param latitude 纬度 * @return double[] x y */
    public static double[] wgs84_To_Gauss6(double longitude, double latitude) { 
        int ProjNo = 0;
        int ZoneWide; // //带宽
        double[] output = new double[2];
        double longitude1, latitude1, longitude0, X0, Y0, xval, yval;
        double a, f, e2, ee, NN, T, C, A, M, iPI;
        iPI = 0.0174532925199433; // //3.1415926535898/180.0;
        ZoneWide = 6; //6度带宽
        a = 6378137.0;
        f = 1.0 / 298.257223563; //WGS84坐标系参数
        //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
        ProjNo = (int) (longitude / ZoneWide);
        longitude0 = (double)(ProjNo * ZoneWide + ZoneWide / 2);
        longitude0 = longitude0 * iPI;
        longitude1 = longitude * iPI; // 经度转换为弧度
        latitude1 = latitude * iPI; // 纬度转换为弧度
        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));
        // 因为是以赤道为Y轴的，与我们南北为Y轴是相反的，所以xy与高斯投影的标准xy正好相反;
        xval = NN
                * (A + (1 - T + C) * A * A * A / 6 + (5 - 18 * T + T * T + 14
                * 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 + 270 * C - 330 * ee)
                * A * A * A * A * A * A / 720);
        X0 = 1000000L * (ProjNo + 1) + 500000L;
        Y0 = 0;
        xval = xval + X0;
        yval = yval + Y0;
        output[0] = xval;
        output[1] = yval;
        return output;
    }

注意这是从WGS84坐标系到高斯投影的转化，百度地图用的经纬度坐标并非是高斯WGS84，但是WGS84是世界通用的坐标系，一般国外都是用这个表示的，经过测试，其精确度还是可以的。

4、坐标距离计算

• 实体类创建（可有可无，没有就传经纬度）

@Data
public class PointEntity implements Serializable { 
    private static final long serialVersionUID = 1L;
    /** * 纬度 */
    public Double x;
    /** * 经度 */
    public Double y;

    public PointEntity() { }

    public PointEntity(Double x, Double y) { 
        this.x = x;
        this.y = y;
    }
}

• 距离计算方法

public static double distanceToPoint(PointEntity pointA, PointEntity pointB){ 
        //jts提供的几何要素工厂类
        GeometryFactory geometryFactory = new GeometryFactory();

        //火星坐标(gcj02)转GPS坐标(WGS84)
        double[] wgsPntA = CoordinateUtil.gcj02_To_Wgs84(pointA.x,pointA.y);
        double[] wgsPntB = CoordinateUtil.gcj02_To_Wgs84(pointB.x,pointB.y);

        //WGS84->高斯6度分带投影
        double[] gaussPntA = wgs84_To_Gauss6(wgsPntA[0],wgsPntA[1]);
        double[] gaussPntB = wgs84_To_Gauss6(wgsPntB[0],wgsPntB[1]);

        //通过几何要素工厂得到point实体
        Point pntA = geometryFactory.createPoint(new Coordinate(gaussPntA[0], gaussPntA[1]));
        Point pntB = geometryFactory.createPoint(new Coordinate(gaussPntB[0], gaussPntB[1]));
        // 两点距离
        return pntA.distance(pntB);
    }

5、测试

• 高德计算的距离
  高德计算距离地址：https://lbs.amap.com/api/javascript-api/example/calcutation/calculate-distance-between-two-markers
  
• 程序计算距离

public static void main(String[] args) { 
        PointEntity pointA = new PointEntity(116.368904, 39.923423);
        PointEntity pointB = new PointEntity(116.387271, 39.922501);
        double len = distanceToPoint(pointA,pointB);
        System.out.println(len);
    }

6、结语

这篇文章作为笔记，也是第一次编写计算经纬度，试过好几种方法，这个计算出来的距离跟高德上可能会有一些偏差，但好在偏差不大，在合理范围内。