C# 生成验证码 方法二

public class ValidateCode
    {
        public ValidateCode()
        {
        }

        /// <summary>
        /// 验证码的最大长度
        /// </summary>
        public int MaxLength
        {
            get { return 10; }
        }

        /// <summary>
        /// 验证码的最小长度
        /// </summary>
        public int MinLength
        {
            get { return 1; }
        }

        /// <summary>
        /// 生成验证码
        /// </summary>
        /// <param name="length">指定验证码的长度</param>
        /// <returns></returns>
        public string CreateValidateCode(int length)
        {
            int[] randMembers = new int[length];
            int[] validateNums = new int[length];
            string validateNumberStr = "";
            //生成起始序列值
            int seekSeek = unchecked((int)DateTime.Now.Ticks);
            Random seekRand = new Random(seekSeek);
            int beginSeek = (int)seekRand.Next(0, Int32.MaxValue - length * 10000);
            int[] seeks = new int[length];
            for (int i = 0; i < length; i++)
            {
                beginSeek += 10000;
                seeks[i] = beginSeek;
            }
            //生成随机数字
            for (int i = 0; i < length; i++)
            {
                Random rand = new Random(seeks[i]);
                int pownum = 1 * (int)Math.Pow(10, length);
                randMembers[i] = rand.Next(pownum, Int32.MaxValue);
            }
            //抽取随机数字
            for (int i = 0; i < length; i++)
            {
                string numStr = randMembers[i].ToString();
                int numLength = numStr.Length;
                Random rand = new Random();
                int numPosition = rand.Next(0, numLength - 1);
                validateNums[i] = Int32.Parse(numStr.Substring(numPosition, 1));
            }
            //生成验证码
            for (int i = 0; i < length; i++)
            {
                validateNumberStr += validateNums[i].ToString();
            }
            return validateNumberStr;
        }

        /// <summary>
        /// 得到验证码图片的长度
        /// </summary>
        /// <param name="validateNumLength">验证码的长度</param>
        /// <returns></returns>
        public static int GetImageWidth(int validateNumLength)
        {
            return (int)(validateNumLength * 12.0);
        }

        /// <summary>
        /// 得到验证码的高度
        /// </summary>
        /// <returns></returns>
        public static double GetImageHeight()
        {
            return 22.5;
        }

        /// <summary>
        /// C# MVC 升级版创建验证码的图片
        /// </summary>
        /// <param name="validateCode">验证码</param>
        public byte[] CreateValidateGraphic(string validateCode)
        {
            Bitmap image = new Bitmap((int)Math.Ceiling(validateCode.Length * 12.0), 22);
            Graphics g = Graphics.FromImage(image);
            try
            {
                //生成随机生成器
                Random random = new Random();
                //清空图片背景色
                g.Clear(Color.White);
                //画图片的干扰线
                for (int i = 0; i < 25; i++)
                {
                    int x1 = random.Next(image.Width);
                    int x2 = random.Next(image.Width);
                    int y1 = random.Next(image.Height);
                    int y2 = random.Next(image.Height);
                    g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2);
                }
                Font font = new Font("Arial", 12, (FontStyle.Bold | FontStyle.Italic));
                LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height),
                                                                    Color.Blue, Color.DarkRed, 1.2f, true);
                g.DrawString(validateCode, font, brush, 3, 2);
                //画图片的前景干扰点
                for (int i = 0; i < 100; i++)
                {
                    int x = random.Next(image.Width);
                    int y = random.Next(image.Height);
                    image.SetPixel(x, y, Color.FromArgb(random.Next()));
                }
                //画图片的边框线
                g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);
                //保存图片数据
                MemoryStream stream = new MemoryStream();
                image.Save(stream, ImageFormat.Jpeg);
                //输出图片流
                return stream.ToArray();
            }
            finally
            {
                g.Dispose();
                image.Dispose();
            }
        }

    }

 @using (Ajax.BeginForm("index", "Home", new { }, new AjaxOptions() { HttpMethod = "Post", OnSuccess = "AfterAdd" }, new { id = "frmSet" }))
                {
                    <div class="en_01">
                        <input placeholder="用户名" name="UserID" type="text" >
                    </div>
                    <div class="en_01">
                        <input placeholder="密码" type="password" name="password" >
                    </div>
                    <div class="en_02">
                        <input placeholder="验证码" type="text"  name="CheckCode" ><img src="/Home/GetCodeImage" id="CodeImage" alt="看不清？换一张" onclick="this.src=‘/Home/GetCodeImage?GUID=‘+ new Date().getTime();">
                    </div>
                    <div class="en_03">
                        <input value="登录" type="submit">
                    </div>
                }
<script>
    function AfterAdd(result) {
        if (result.isOk == "ok") {
            window.top.location.href = result.goUrl;
        }
        else {
            $("#CodeImage").attr("src", "/Home/GetCodeImage?GUID=" + new Date().getTime());
            alert(result.msg);

        }
    }

</script>

//会员登录
        [HttpPost]
        public ActionResult Index(FormCollection form)
        {

            string UserID =Tool.GetSafeSqlandHtml(Request["UserID"]);
            string pwd = Tool.GetSafeSqlandHtml(Request["password"]);
            string CheckCode =Tool.GetSafeSqlandHtml( Request["CheckCode"]);
            if (Session["ValidateCode"] == null || CheckCode != Session["ValidateCode"].ToString())
            {
                return Json(new { isOk = "erro", msg = "验证码错误" });
            }
            if (string.IsNullOrEmpty(UserID) || string.IsNullOrEmpty(pwd))
            {
                return Json(new { isOk = "erro", msg = "请输入用户名和密码" });
            }
            string reMsg = "";
            if (BLL.Member.UserLogin(UserID, pwd, true, out reMsg))
            {
                const string goUrl = "/Default/Index";
                return Json(new { isOk = "ok", goUrl = goUrl });
                
            }
            return Json(new { isOk = "erro", msg = reMsg });
        }
        //生成验证码图片
        public ActionResult GetCodeImage()
        {
            ValidateCode vCode = new ValidateCode();
            string code = vCode.CreateValidateCode(5);
            Session["ValidateCode"] = code;
            byte[] bytes = vCode.CreateValidateGraphic(code);
            return File(bytes, @"image/jpeg");
        }