.Net Core 实现图片验证码

private static string RndNum(int VcodeNum)
        {
            //验证码可以显示的字符集合  
            string Vchar = "0,1,2,3,4,5,6,7,8,9,a,b,c,d,e,f,g,h,i,j,k,l,m,n,p" +
                ",q,r,s,t,u,v,w,x,y,z,A,B,C,D,E,F,G,H,I,J,K,L,M,N,P,P,Q" +
                ",R,S,T,U,V,W,X,Y,Z";
            string[] VcArray = Vchar.Split(new Char[] { ',' });//拆分成数组   
            string code = "";//产生的随机数  
            int temp = -1;//记录上次随机数值，尽量避避免生产几个一样的随机数  

            Random rand = new Random();
            //采用一个简单的算法以保证生成随机数的不同  
            for (int i = 1; i < VcodeNum + 1; i++)
            {
                if (temp != -1)
                {
                    rand = new Random(i * temp * unchecked((int)DateTime.Now.Ticks));//初始化随机类  
                }
                int t = rand.Next(61);//获取随机数  
                if (temp != -1 && temp == t)
                {
                    return RndNum(VcodeNum);//如果获取的随机数重复，则递归调用  
                }
                temp = t;//把本次产生的随机数记录起来  
                code += VcArray[t];//随机数的位数加一  
            }
            return code;
        }

public static MemoryStream Create(out string code, int numbers = 4)
        {
            code = RndNum(numbers);
            //Bitmap img = null;
            //Graphics g = null;
            MemoryStream ms = null;
            Random random = new Random();
            //验证码颜色集合  
            Color[] c = { Color.Black, Color.Red, Color.DarkBlue, Color.Green, Color.Orange, Color.Brown, Color.DarkCyan, Color.Purple };

            //验证码字体集合
            string[] fonts = { "Verdana", "Microsoft Sans Serif", "Comic Sans MS", "Arial", "宋体" };


            using (var img = new Bitmap((int)code.Length * 18, 32))
            {
                using (var g = Graphics.FromImage(img))
                {
                    g.Clear(Color.White);//背景设为白色

                    //在随机位置画背景点  
                    for (int i = 0; i < 100; i++)
                    {
                        int x = random.Next(img.Width);
                        int y = random.Next(img.Height);
                        g.DrawRectangle(new Pen(Color.LightGray, 0), x, y, 1, 1);
                    }
                    //验证码绘制在g中  
                    for (int i = 0; i < code.Length; i++)
                    {
                        int cindex = random.Next(7);//随机颜色索引值  
                        int findex = random.Next(5);//随机字体索引值  
                        Font f = new Font(fonts[findex], 15, FontStyle.Bold);//字体  
                        Brush b = new SolidBrush(c[cindex]);//颜色  
                        int ii = 4;
                        if ((i + 1) % 2 == 0)//控制验证码不在同一高度  
                        {
                            ii = 2;
                        }
                        g.DrawString(code.Substring(i, 1), f, b, 3 + (i * 12), ii);//绘制一个验证字符  
                    }
                    ms = new MemoryStream();//生成内存流对象  
                    img.Save(ms, ImageFormat.Jpeg);//将此图像以Png图像文件的格式保存到流中  
                }
            }

            return ms;
        }

 HttpContext.Session.SetString("LoginValidateCode", code);

<img style="justify-content:center" id="code" src="/Users/Login/GetVerifyCode"  />

 function GetCode() {
        $.ajax({
            type: "GET",
            url: "/Users/Login/GetVerifyCode",
            data: {},
            dataType: "json",
            success: function (data) {
            },
            complete: function () {
                $("#code").attr('src', '/Users/Login/GetVerifyCode')
            }
        });
    }