多边形中心坐标的计算

本文主要是介绍多边形中心坐标的计算，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

import java.util.ArrayList;
import java.util.List;
/**
* 坐标以及电子围栏相关的工具类
*
*/
public class PointUtil {

public static void main(String[] args) {
String str="114.316587,30.671626#114.325921,30.683437#114.342122,30.689342#114.359009,30.695246#114.377066,30.692884#114.393304,30.678417#114.412289,30.650953#114.426107,30.625253#114.433703,30.595853#114.444368,30.560458#114.466705,30.527415#114.457264,30.517327#114.454002,30.503097#114.458465,30.474631#114.430828,30.466313#114.397697,30.460362#114.343281,30.456778#114.305086,30.457354#114.269101,30.468743#114.23449,30.489598#114.182713,30.522872#114.17296,30.535364#114.167328,30.55022#114.165783,30.575754#114.167155,30.591715#114.161492,30.606935#114.160461,30.619049#114.170589,30.627469#114.206123,30.623481#114.233932,30.629832#114.184837,30.704361#114.187927,30.776472#114.233589,30.780122#114.238567,30.717035#114.248609,30.66835#114.284744,30.659813#";

}
/**
* 传入字符串类型的坐标组；经纬度“，”分隔；坐标之间“#”分隔；以“#”好结束
* @return
*/
public static boolean is(String str,double x,double y){
List<Point> list = getxyUtil(str);
Point[] ps2 = new Point[list.size()];
for(int i=0;i<list.size();i++){
ps2[i]=list.get(i);
}
Point n1 = new Point(x,y);
if(isPtInPoly(n1.getX() , n1.getY() , ps2)){
return true;
}
return false;
}
/**
* 传入经度，维度；和需要判断的多边形坐标组
* @param ALon
* @param ALat
* @param ps
* @return
*/
public static boolean isPtInPoly (double ALon , double ALat , Point[] ps) {
int iSum, iCount, iIndex;
double dLon1 = 0, dLon2 = 0, dLat1 = 0, dLat2 = 0, dLon;
if (ps.length < 3) {
return false;
}
iSum = 0;
iCount = ps.length;
for (iIndex = 0; iIndex<iCount;iIndex++) {
if (iIndex == iCount - 1) {
dLon1 = ps[iIndex].getX();
dLat1 = ps[iIndex].getY();
dLon2 = ps[0].getX();
dLat2 = ps[0].getY();
} else {
dLon1 = ps[iIndex].getX();
dLat1 = ps[iIndex].getY();
dLon2 = ps[iIndex + 1].getX();
dLat2 = ps[iIndex + 1].getY();
}
// 以下语句判断A点是否在边的两端点的水平平行线之间，在则可能有交点，开始判断交点是否在左射线上
if (((ALat >= dLat1) && (ALat < dLat2)) || ((ALat >= dLat2) && (ALat < dLat1))) {
if (Math.abs(dLat1 - dLat2) > 0) {
//得到 A点向左射线与边的交点的x坐标：
dLon = dLon1 - ((dLon1 - dLon2) * (dLat1 - ALat) ) / (dLat1 - dLat2);
// 如果交点在A点左侧（说明是做射线与边的交点），则射线与边的全部交点数加一：
if (dLon < ALon) {
iSum++;
}
}
}
}
if ((iSum % 2) != 0) {
return true;
}
return false;
}
/**
* 传入字符串坐标组；转为集合；114.288221,30.593268#114.321866,30.580559#114.311223,30.560015#
* @param str
* @return
*/
public static List<Point> getxyUtil(String str){
List<Point> list = new ArrayList<>();
while (str.indexOf("#")!=-1) {
String str1 = str.substring(0, str.indexOf("#"));//40.01,40.12
Point pd = new Point(Double.valueOf(str1.substring(0, str1.indexOf(","))),Double.valueOf(str1.substring(str1.indexOf(",")+1)));
list.add(pd);
str=str.substring(str.indexOf("#")+1);
}
while (str.indexOf(";")!=-1) {
String str1 = str.substring(0, str.indexOf(";"));//40.01,40.12
Point pd = new Point(Double.valueOf(str1.substring(0, str1.indexOf(","))),Double.valueOf(str1.substring(str1.indexOf(",")+1)));
list.add(pd);
str=str.substring(str.indexOf(";")+1);
}
return list;
}
/**
* 获取多边形的中心
* @param str
* @return
*/
public static PageData getCenterOfGravityPoint(String str ) {
PageData data = new PageData();
List<Point> mPoints = getxyUtil(str);
double area = 0.0;//多边形面积
double Gx = 0.0, Gy = 0.0;// 重心的x、y
for (int i = 1; i <= mPoints.size(); i++) {
double iLat = mPoints.get(i % mPoints.size()).getX();
double iLng = mPoints.get(i % mPoints.size()).getY();
double nextLat = mPoints.get(i - 1).getX();
double nextLng = mPoints.get(i - 1).getY();
double temp = (iLat * nextLng - iLng * nextLat) / 2.0;
area += temp;
Gx += temp * (iLat + nextLat) / 3.0;
Gy += temp * (iLng + nextLng) / 3.0;
}
Gx = Gx / area;
Gy = Gy / area;
data.put("x", String.valueOf(Gx).substring(0, String.valueOf(Gx).indexOf(".")+7));
data.put("y", String.valueOf(Gy).substring(0, String.valueOf(Gy).indexOf(".")+7));
return data;
}


}

class Point {
private Double x;
private Double y;
public Point (Double x , Double y) {
this.x = x;
this.y = y;
}
public Double getX() {
return x;
}
public void setX(Double x) {
this.x = x;
}
public Double getY() {
return y;
}
public void setY(Double y) {
this.y = y;
}
}