MVC小系列（六）【无刷新的验证码】

做个无刷新的验证码功能：

第一步：首先，在公用项目中建立一个生成图片验证码的类型ValidateCode

 /// <summary>
    /// 生成验证码对象
    /// </summary>
    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>
        /// 创建验证码的图片
        ///</summary>
        ///<param name="containsPage">要输出到的page对象</param>
        ///<param name="validateNum">验证码</param>
        public byte[] CreateValidateGraphic(string validateCode)
        {
            Bitmap image = new Bitmap((int)Math.Ceiling(validateCode.Length * 14.0), 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", 14, (FontStyle.Bold | FontStyle.Italic));
                LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height),
                Color.Blue, Color.DarkRed, 1.5f, 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();
            }
        }
    }

第二步：

在当前公用的controller中添加一个返回文件类型的action,当然也可以是所有返回类型的基类ActionResult，这个方法用来返回一个图像对象

 /// <summary>
        /// 生成验证码图像对象
        /// </summary>
        /// <returns></returns>
        public ActionResult GetValidateCode()
        {
            ValidateCode vCode = new ValidateCode();
            string code = vCode.CreateValidateCode(4);
            Session["ValidateCode"] = code;
            byte[] bytes = vCode.CreateValidateGraphic(code);
            return File(bytes, @"image/jpeg");
        }
        /// <summary>
        /// 得到当前验证码
        /// </summary>
        /// <returns></returns>
        public ActionResult GetCurrentValidateCode()
        {
            return Content(Session["ValidateCode"].ToString());
        }

第三步：在View页面显示

<div id="ValidateCodeSpan">
                       请输入验证码：@Html.TextBox("VCode")
                       <img id="valiCode" style="cursor: pointer;" src="/Home/GetValidateCode" alt="看不清？请点我" />
                       @Html.Hidden("ValidateCode")
  
    <script type="text/javascript">
        $(function () {
            //首次加载
            $("#valiCode").attr("src", "/Home/GetValidateCode?time=" + (new Date()).getTime());
            $.get("/Home/GetCurrentValidateCode", function (data) {
                $("#ValidateCode").val(data);
            });
            //单击验证码事件
            $("#valiCode").bind("click", function () {
                this.src = "/Home/GetValidateCode?time=" + (new Date()).getTime();
                $.get("/Home/GetCurrentValidateCode", function (data) {
                    $("#ValidateCode").val(data);
                });
            });
        });
          </script>
    
</div>