java实现判断一个经纬度坐标是否在一个多边形内（经自己亲测）
1.在高德地图上绘制的多边形；经纬度逗号分隔格式；上面是用来方便存坐标的对象；下面是方法测试；直接复制代码即可运行 public 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; } } public class Test01 { public static void main(String[] args) { //114.331951,30.64091#114.341049,30.610185#114.331436,30.588058#114.312038,30.56393#114.293498,30.558609#114.267922,30.563784#114.231185,30.57945#114.212303,30.601616#114.235649,30.626878#114.280624,30.646818# Map [] map=new Map[]{}; Point[] ps = new Point[] { new Point(114.309914,30.599556),//114.309914,30.599556 new Point(114.295688,30.592879),//114.295688,30.592879 new Point(114.292812,30.587726), //114.292812,30.587726 new Point(114.292812,30.587726), //114.292812,30.587726 new Point(114.30058,30.580318),//114.30058,30.580318 new Point(114.303606,30.586959),//114.303606,30.586959 new Point(114.304534,30.594751),//114.304534,30.594751 new Point(114.30838,30.590131),//114.30838,30.590131 new Point(114.308651,30.584182),//114.308651,30.584182 new Point(114.304495,30.584015),//114.304495,30.584015 new Point(114.301301,30.578759),//114.301301,30.578759 new Point(114.309437,30.578528),//114.309437,30.578528 new Point(114.323282,30.592786)};//114.323282,30.592786 Point n1 = new Point(114.303217,30.583553); Point n2 = new Point(114.307336,30.597592); Point n3 = new Point(114.286565,30.590056); Point y1 = new Point(114.227342,30.587987); Point y2 = new Point(120.1866 , 30.2672); Point y4 = new Point(120.1869 , 30.2718); System.out.println( "n1:" + isPtInPoly(n1.getX() , n1.getY() , ps)); System.out.println( "n2:" + isPtInPoly(n2.getX() , n2.getY() , ps)); System.out.println( "n3:" + isPtInPoly(n3.getX() , n3.getY() , ps)); System.out.println( "y1:" + isPtInPoly(y1.getX() , y1.getY() , ps)); System.out.println( "y2:" + isPtInPoly(y2.getX() , y2.getY() , ps)); System.out.println( "y4:" + isPtInPoly(y4.getX() , y4.getY() , ps)); } 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; } }
