Java类判断地图上某点是否在多边形区域内

实现方法如下：

    import java.awt.geom.Point2D;      import java.util.ArrayList;      import java.util.List;      import java.util.HashMap;    import java.util.Map;          /**       * 根据点的经纬度判断是否在多边形区域内     */      public class OrderMapTest {                    public static void main(String[] args) {              // 被检测的经纬度点              Map<String, String> orderLocation = new HashMap<String, String>();            orderLocation.put("X", "117.228117");              orderLocation.put("Y", "31.830429");              // 商业区域（百度多边形区域经纬度集合）              String partitionLocation = "31.839064_117.219116,31.83253_117.219403,31.828511_117.218146,31.826763_117.219259,31.826118_117.220517,31.822713_117.23586,31.822958_117.238375,31.838512_117.23798,31.839617_117.226194,31.839586_117.222925";              System.out.println(isInPolygon(orderLocation, partitionLocation));          }                     /**            * 判断当前位置是否在多边形区域内            * @param orderLocation 当前点           * @param partitionLocation 区域顶点           * @return            */            public static boolean isInPolygon(Map<String, String> orderLocation,String partitionLocation){                              double p_x =Double.parseDouble(orderLocation.get("X"));                double p_y =Double.parseDouble(orderLocation.get("Y"));                Point2D.Double point = new Point2D.Double(p_x, p_y);                       List<Point2D.Double> pointList= new ArrayList<Point2D.Double>();                String[] strList = partitionLocation.split(",");                            for (String str : strList){                  String[] points = str.split("_");                  double polygonPoint_x=Double.parseDouble(points[1]);                    double polygonPoint_y=Double.parseDouble(points[0]);                    Point2D.Double polygonPoint = new Point2D.Double(polygonPoint_x,polygonPoint_y);                    pointList.add(polygonPoint);                }                return IsPtInPoly(point,pointList);            }            /**            * 返回一个点是否在一个多边形区域内， 如果点位于多边形的顶点或边上，不算做点在多边形内，返回false           * @param point            * @param polygon            * @return            */            public static boolean checkWithJdkGeneralPath(Point2D.Double point, List<Point2D.Double> polygon) {                java.awt.geom.GeneralPath p = new java.awt.geom.GeneralPath();                Point2D.Double first = polygon.get(0);                p.moveTo(first.x, first.y);                polygon.remove(0);                for (Point2D.Double d : polygon) {                   p.lineTo(d.x, d.y);                }                p.lineTo(first.x, first.y);                p.closePath();                return p.contains(point);           }                    /**           * 判断点是否在多边形内，如果点位于多边形的顶点或边上，也算做点在多边形内，直接返回true          * @param point 检测点           * @param pts   多边形的顶点           * @return      点在多边形内返回true,否则返回false           */           public static boolean IsPtInPoly(Point2D.Double point, List<Point2D.Double> pts){                              int N = pts.size();               boolean boundOrVertex = true; //如果点位于多边形的顶点或边上，也算做点在多边形内，直接返回true               int intersectCount = 0;//cross points count of x                double precision = 2e-10; //浮点类型计算时候与0比较时候的容差               Point2D.Double p1, p2;//neighbour bound vertices               Point2D.Double p = point; //当前点                              p1 = pts.get(0);//left vertex                       for(int i = 1; i <= N; ++i){//check all rays                               if(p.equals(p1)){                       return boundOrVertex;//p is an vertex                   }                                      p2 = pts.get(i % N);//right vertex                               if(p.x < Math.min(p1.x, p2.x) || p.x > Math.max(p1.x, p2.x)){//ray is outside of our interests                                       p1 = p2;                        continue;//next ray left point                   }                                      if(p.x > Math.min(p1.x, p2.x) && p.x < Math.max(p1.x, p2.x)){//ray is crossing over by the algorithm (common part of)                       if(p.y <= Math.max(p1.y, p2.y)){//x is before of ray                                               if(p1.x == p2.x && p.y >= Math.min(p1.y, p2.y)){//overlies on a horizontal ray                               return boundOrVertex;                           }                                                      if(p1.y == p2.y){//ray is vertical                                                       if(p1.y == p.y){//overlies on a vertical ray                                   return boundOrVertex;                               }else{//before ray                                   ++intersectCount;                               }                            }else{//cross point on the left side                                                       double xinters = (p.x - p1.x) * (p2.y - p1.y) / (p2.x - p1.x) + p1.y;//cross point of y                                                       if(Math.abs(p.y - xinters) < precision){//overlies on a ray                                   return boundOrVertex;                               }                                                              if(p.y < xinters){//before ray                                   ++intersectCount;                               }                            }                       }                   }else{//special case when ray is crossing through the vertex                                       if(p.x == p2.x && p.y <= p2.y){//p crossing over p2                                               Point2D.Double p3 = pts.get((i+1) % N); //next vertex                                               if(p.x >= Math.min(p1.x, p3.x) && p.x <= Math.max(p1.x, p3.x)){//p.x lies between p1.x & p3.x                               ++intersectCount;                           }else{                               intersectCount += 2;                           }                       }                   }                               p1 = p2;//next ray left point               }                              if(intersectCount % 2 == 0){//偶数在多边形外                   return false;               } else { //奇数在多边形内                   return true;               }           }        }