根据四个点坐标求两个直线的交叉点坐标（Java&JavaScript）

Java

	//计算两条直线的交点
    //输入四个点，前两个点确定线段1，后两个点确定线段2
    //输出交点坐标
    public static void main(String args[]){
    
    
        double[] point1= new double[]{
    
    0,0};
        double[] point2 = new double[]{
    
    2,2};

        double[] point3 = new double[]{
    
    0,2};
        double[] point4 = new double[]{
    
    2,0};
        double[] node = cross(point1,point2,point3,point4);
        if(node==null)System.out.println(false);
        else System.out.println(node[0]+","+node[1]);
        HashSet<String> set = new HashSet<>();
        set.add(node[0]+":"+node[1]);
        for(String item:set){
    
    
            System.out.println(item);
        }
    }

    public static double[] cross(double[] point1,double[] point2,double[] point3,double[] point4){
    
    
        if((point2[1]-point1[1])*(point4[0]-point3[0])==(point4[1]-point3[1])*(point2[0]-point1[0]))return null;
        if(point2[0]-point1[0]==0){
    
    
            double k2 = (point4[1]-point3[1])/(point4[0]-point3[0]);
            double b2 = point3[1]-point3[0]*k2;
            double cross_x = point1[0];
            double cross_y = k2*cross_x+b2;
            return new double[]{
    
    cross_x,cross_y};
        }
        if(point4[0]-point3[0]==0){
    
    
            double k1 = (point2[1]-point1[1])/(point2[0]-point1[0]);
            double b1 = point1[1]-point1[0]*k1;
            double cross_x = point3[0];
            double cross_y = k1*cross_x+b1;
            return new double[]{
    
    cross_x,cross_y};
        }
        double k1 = (point2[1]-point1[1])/(point2[0]-point1[0]);
        double b1 = point1[1]-point1[0]*k1;
        double k2 = (point4[1]-point3[1])/(point4[0]-point3[0]);
        double b2 = point3[1]-point3[0]*k2;
        double cross_x = (b1-b2)/(k2-k1);
        double cross_y = k1*cross_x+b1;
        return new double[]{
    
    cross_x,cross_y};
    }

JavaScript

//四个坐标 两条直线 求交叉点
function segmentsIntr(a, b, c, d){
    
    
    /** 1 解线性方程组, 求线段交点. **/
// 如果分母为0 则平行或共线, 不相交
    var denominator = (b[1] - a[1])*(d[0] - c[0]) - (a[0] - b[0])*(c[1] - d[1]);
    if (denominator==0) {
    
    
        return false;
    }
// 线段所在直线的交点坐标 (x , y)
    var x = ( (b[0] - a[0]) * (d[0] - c[0]) * (c[1] - a[1])
        + (b[1] - a[1]) * (d[0] - c[0]) * a[0]
        - (d[1] - c[1]) * (b[0] - a[0]) * c[0] ) / denominator ;
    var y = -( (b[1] - a[1]) * (d[1] - c[1]) * (c[0] - a[0])
        + (b[0] - a[0]) * (d[1] - c[1]) * a[1]
        - (d[0] - c[0]) * (b[1] - a[1]) * c[1] ) / denominator;
    /** 2 判断交点是否在两条线段上 **/
    if (
        // 交点在线段1上
        (x - a[0]) * (x - b[0]) <= 0 && (y - a[1]) * (y - b[1]) <= 0
        // 且交点也在线段2上
        && (x - c[0]) * (x - d[0]) <= 0 && (y - c[1]) * (y - d[1]) <= 0
    ){
    
    
        // 返回交点p
        return [x,y]
    }
    //否则不相交
    return false
}