geotools：Shortest distance between a line segment and a point in WGS84 crs using geotools api

In geotools you can find distance between two geometries using the distance function in Geometry class. There is a Point subclass of Geometry but no line segment subclass of Geometry. There is however LineSegment class which derives from LineString which is not subclass of Geometry class. I tried using JTS but it appears as JTS is only for Cartesian coordinate system.

在geotools中，可以使用Geometry类中的distance函数查找两个几何图形之间的距离。有一个几何体的点子类，但没有几何体的线段子类。然而，有一个LineSegment类派生自LineString，它不是Geometry类的子类。我尝试使用JTS，但似乎JTS只适用于笛卡尔坐标系。

Question: How to find shortest distance (in meters) between a LineSegment and a Point in WGS84 crs.

Please note: I know there are answers available on SO for doing this without using geotools. Since we are using geotools in our project and code maintainability is very important I want to do it in geotools.

https://stackoverflow.com/questions/24809534/shortest-distance-between-a-line-segment-and-a-point-in-wgs84-crs-using-geotools?r=SearchResults

 之前曾经求过已知p1，p2，p4，和p3-p4的距离，求p3的坐标。。。

如今已知p1，p2，p3，求p4。我们得知隐含逻辑，p4在p1-p2所在的直线上，p3p4垂直于p1p2。

由于已知p1，p2。可得p1-p2直线方程，y-y1=k(x-x1)。其中k=(y2-y1)/(x2-x1)。写成一般形式：Ax+By+C=0的话，就是kx-y+y1+kx1=0。

>>求点到直线的最短距离及垂足: https://wenku.baidu.com/view/5c511ffd6c1aff00bed5b9f3f90f76c661374c38.html

方法不止一种。。。我使用的是自己推导的：

条件一（垂直定理，斜率乘积为负一）方程：(y4-y3)/(x4-x3)*(y2-y1)/(x2-x1)=-1      

条件二（共线定理，点4在点12所在的直线）方程：(y2-y1)/(x2-x1)=(y4-y1)/(x4-x1)

由于k=(y2-y1)/(x2-x1)。所以上面两个方程可以简写成：

方程一：(y4-y3)/(x4-x3)*k=-1

方程二：k=(y4-y1)/(x4-x1)

同时把y4提到等式左边可得：

方程一：y4=y3-(x4-x3)/k

方程二：y4=y1+(x4-x1)*k

所以可以求得：

x4 = (y3+x3/k-y1+k*x1)/(k+1/k)

y4=y1+k*(x4-x1)

要不要先判断该点是否在线上。。。

>>Snap a Point to a Line：https://docs.geotools.org/latest/userguide/library/jts/snap.html

>>GeodeticCalculator：https://docs.geotools.org/stable/userguide/library/referencing/calculator.html

>>JTS Java空间几何计算、距离、最近点、subLine等 稳健的一比，持续更新中：https://blog.csdn.net/abu935009066/article/details/115304685

>>JTS计算空间坐标梳理：https://blog.csdn.net/ZHANGHUI3239619/article/details/120885305