winform随机验证码

首先，窗体的Form_Load加载时调用实现随机数字或者字母的方法

 private void Form1_Load(object sender, EventArgs e)
        {
            checkCode = GetRandomCode(4);//获取4个随机的数字或字母
            CreateImage(checkCode);//实现验证码图片
        }

然后，实现4个随机的数字或者字母的方法

 private string GetRandomCode(int CodeCount)
        {
            string allChar = "0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F,G,H,i,J,K,M,N,P,Q,R,S,T,U,W,X,Y,Z";
            string[] allCharArray = allChar.Split(',');
            string RandomCode = "";
            int temp = -1;

            Random rand = new Random();
            for (int i = 0; i < CodeCount; i++)
            {
                if (temp != -1)
                {
                    rand = new Random(temp * i * ((int)DateTime.Now.Ticks));
                }

                int t = rand.Next(33);

                while (temp == t)
                {
                    t = rand.Next(33);
                }

                temp = t;
                RandomCode += allCharArray[t];
            }

            return RandomCode;
        }

最后，把获取出来的4个随机数字或者字母画成图片，控件是pictureBox

 private void CreateImage(string checkCode)
        {
            int iwidth = (int)(checkCode.Length * 14);
            System.Drawing.Bitmap image = new System.Drawing.Bitmap(iwidth, 21);
            Graphics g = Graphics.FromImage(image);
            Font f = new System.Drawing.Font("Arial ", 10);
            Brush b = new System.Drawing.SolidBrush(Color.Black);
            Brush r = new System.Drawing.SolidBrush(Color.FromArgb(166, 8, 8));

            g.Clear(System.Drawing.ColorTranslator.FromHtml("#99C1CB"));//背景色

            char[] ch = checkCode.ToCharArray();
            for (int i = 0; i < ch.Length; i++)
            {
                if (ch[i] >= '0' && ch[i] <= '9')
                {
                    //数字用红色显示
                    g.DrawString(ch[i].ToString(), f, r, 3 + (i * 12), 3);
                }
                else
                {   //字母用黑色显示
                    g.DrawString(ch[i].ToString(), f, b, 3 + (i * 12), 3);
                }
            }
            System.IO.MemoryStream ms = new System.IO.MemoryStream();
            image.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
            pictureBox1.Image = image;
        }

最后，如果需要重新加载图片，则点击pictureBox的点击事件重新调用一下事件即可

 private void pictureBox1_Click(object sender, EventArgs e)
        {
            checkCode = GetRandomCode(4);
            CreateImage(checkCode);
        }

整个的winform随机验证码完成。