java判断某个点是否在所画多边形/圆形内

package com.ardo.util.circle;  import java.util.ArrayList; import java.util.List;  /**  * java判断某个点是否在所画范围内(多边形【isPtInPoly】/圆形【distencePC】)  * @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  * @author   ardo  */  public class IsPtInPoly {      /**    * 判断点是否在多边形内    * @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 point, List<Point2D> 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 p1, p2;//neighbour bound vertices      Point2D 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 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;      }          }       /**    * 判断是否在圆形内    * @param p    * @param c    * @return    */   public static String distencePC(Point2D p,Circle c){//判断点与圆心之间的距离和圆半径的关系     String s ;     double d2 = Math.hypot( (p.getX() - c.getCC().getX() ), (p.getY() - c.getCC().getY()) );     System.out.println("d2=="+d2);     double r = c.getR();     if(d2 > r){        s = "圆外";     }else if(d2 < r){        s = "圆内";     }else{        s = "圆上";     }     return s;   }       public static void main(String[] args) {            Point2D point = new Point2D(116.404072, 39.916605);            // 测试一个点是否在多边形内      List<Point2D> pts = new ArrayList<Point2D>();      pts.add(new Point2D(116.395, 39.910));      pts.add(new Point2D(116.394, 39.914));      pts.add(new Point2D(116.403, 39.920));      pts.add(new Point2D(116.402, 39.914));      pts.add(new Point2D(116.410, 39.913));            if(isPtInPoly(point, pts)){        System.out.println("点在多边形内");      }else{        System.out.println("点在多边形外");      }           // 测试一个点是否在圆形内      Point2D centerPoint = new Point2D(116.404172, 39.916605);      Circle c = new Circle();     c.setCC(centerPoint);     c.setR(0.0056);     String s = distencePC(point,c);     System.out.println("点是否在圆内："+s);   }     } 

/**  * 圆形类  * @author ardo  *  */ public class Circle {    private double r;    private Point2D cc;        public void setR(double a){       r = a;    }    public void setCC(Point2D centerOfCir){       cc = centerOfCir;    }    public double getR(){       return r;    }    public Point2D getCC(){       return cc;    } } 

public class Point2D {      public double x;   public double y;      public Point2D(double x, double y) {     super();     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;   }    }