C# 随机生成验证码

使用C#根据需要的验证码长度，随机生成验证码

public class AuthcodeHelper
    {

        /// <summary>
        /// 获取验证码
        /// </summary>
        /// <param name="length">验证码长度</param>
        /// <returns>返回生成的验证码字符串</returns>
        public static string GetRandomAuthcode(int length)
        {

            string chkCode = string.Empty;
           
            //验证码的字符集，去掉了一些容易混淆的字符 
            char[] character = { '2', '3', '4', '5', '6', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'J', 'K', 'L', 'M', 'N', 'P', 'R', 'S', 'T', 'W', 'X', 'Y' };
           
            Random rnd = new Random();
            //生成验证码字符串 
            for (int i = 0; i < length; i++)
            {
                chkCode += character[rnd.Next(character.Length)];
            }

            return chkCode;
        }

        /// <summary>
        /// 获取图片验证码
        /// </summary>
        /// <param name="authcode"></param>
        /// <param name="imageWidth"></param>
        /// <param name="imageHeight"></param>
        /// <returns></returns>
        public static MemoryStream GetImage(string authcode, int imageWidth = 110, int imageHeight = 30)
        {
            try
            {
                //颜色列表，用于验证码、噪线、噪点 
                Color[] color = { Color.Black, Color.Red, Color.Blue, Color.Green, Color.Orange, Color.Brown, Color.Brown, Color.DarkBlue };
                //字体列表，用于验证码 
                string[] font = { "Times New Roman", "MS Mincho", "Book Antiqua", "Gungsuh", "PMingLiU", "Impact" };
                Random rnd = new Random();
                Bitmap bmp = new Bitmap(imageWidth, imageHeight);
                Graphics g = Graphics.FromImage(bmp);
                g.Clear(Color.White);
                //画噪线 
                for (int i = 0; i < 4; i++)
                {
                    int x1 = rnd.Next(imageWidth);
                    int y1 = rnd.Next(imageHeight);
                    int x2 = rnd.Next(imageWidth);
                    int y2 = rnd.Next(imageHeight);
                    Color clr = color[rnd.Next(color.Length)];
                    g.DrawLine(new Pen(clr), x1, y1, x2, y2);
                }
                //画验证码字符串 
                for (int i = 0; i < authcode.Length; i++)
                {
                    string fnt = font[rnd.Next(font.Length)];
                    Font ft = new Font(fnt, 14);
                    Color clr = color[rnd.Next(color.Length)];
                    g.DrawString(authcode[i].ToString(), ft, new SolidBrush(clr), (float)i * 20 + 8, (float)4);
                }
                //画噪点 
                for (int i = 0; i < 20; i++)
                {
                    int x = rnd.Next(bmp.Width);
                    int y = rnd.Next(bmp.Height);
                    Color clr = color[rnd.Next(color.Length)];
                    bmp.SetPixel(x, y, clr);
                }
                g.DrawRectangle(new Pen(Color.Blue, 1), 0, 0, bmp.Width - 1, bmp.Height - 1);

                MemoryStream ms = new MemoryStream();
                try
                {
                    bmp.Save(ms, ImageFormat.Png);
                }
                finally
                {
                    //显式释放资源 
                    bmp.Dispose();
                    g.Dispose();
                }

                return ms;
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
                return null;
            }

        }
   
    }