ASP.Net MVC 生成安全验证码

---------html　　　　　　

<td>验证码：</td>

           <td>

               <img src="/Login/CheckCode?ID=1" id="imgCode" alt="单击可刷新" onclick="ClickRemoveChangeCode()"  />

               <div style="float:right; margin-top: 5px;">

                   <a href="javascript:void(0)" onclick="ClickRemoveChangeCode();return false;">看不清，换一张</a>

               </div>

           </td>

-----------jquery

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//单击重新改变验证码 function ClickRemoveChangeCode() {     var code = $("#imgCode").attr("src");     $("#imgCode").attr("src", code + "1"); }

------------asp.net mvc 返回文件地址　　　　

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/// <summary> /// 验证码的校验 /// </summary> /// <param name="context"></param> /// <returns></returns> public ActionResult CheckCode() {     //生成验证码     ValidateCode validateCode = new ValidateCode();     string code = validateCode.CreateValidateCode(4);     Session["ValidateCode"] = code;     byte[] bytes = validateCode.CreateValidateGraphic(code);     return File(bytes, @"image/jpeg"); }   /// <summary> /// 验证验证码是否正确 /// </summary> /// <param name="num"></param> /// <returns></returns> public bool CheckValidateCode(string num) { string cnum = Session["ValidateCode"] == null ? "": Session["ValidateCode"].ToString(); if (num== cnum && !string.IsNullOrEmpty(num)) {      return true; }  else {     return false; } }

----生成验证码和绘制背景的类

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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;         }           //C# MVC 升级版         /// <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 * 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();             }         }           /// <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;         }       }