本文实例为大家分享了java判断某个点是否在所画范围内的具体代码，供大家参考，具体内容如下

IsPtInPoly.java

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); } }

Circle.java

/** * 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; } }

Point2D.java

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; } }

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