1   public class CaptchaRender
  2     {
  3         public CaptchaRender()
  4         {
  5         }
  6 
  7         /// <summary>
  8         /// 验证码的最大长度
  9         /// </summary>
 10         public int MaxLength
 11         {
 12             get { return 10; }
 13         }
 14 
 15         /// <summary>
 16         /// 验证码的最小长度
 17         /// </summary>
 18         public int MinLength
 19         {
 20             get { return 1; }
 21         }
 22 
 23         /// <summary>
 24         /// 生成验证码
 25         /// </summary>
 26         /// <param name="length">指定验证码的长度</param>
 27         /// <returns></returns>
 28         public string CreateValidateCode(int length)
 29         {
 30             int[] randMembers = new int[length];
 31             int[] validateNums = new int[length];
 32             string validateNumberStr = "";
 33             //生成起始序列值
 34             int seekSeek = unchecked((int) DateTime.Now.Ticks);
 35             Random seekRand = new Random(seekSeek);
 36             int beginSeek = (int) seekRand.Next(0, Int32.MaxValue - length*10000);
 37             int[] seeks = new int[length];
 38             for (int i = 0; i < length; i++)
 39             {
 40                 beginSeek += 10000;
 41                 seeks[i] = beginSeek;
 42             }
 43             //生成随机数字
 44             for (int i = 0; i < length; i++)
 45             {
 46                 Random rand = new Random(seeks[i]);
 47                 int pownum = 1*(int) Math.Pow(10, length);
 48                 randMembers[i] = rand.Next(pownum, Int32.MaxValue);
 49             }
 50             //抽取随机数字
 51             for (int i = 0; i < length; i++)
 52             {
 53                 string numStr = randMembers[i].ToString();
 54                 int numLength = numStr.Length;
 55                 Random rand = new Random();
 56                 int numPosition = rand.Next(0, numLength - 1);
 57                 validateNums[i] = Int32.Parse(numStr.Substring(numPosition, 1));
 58             }
 59             //生成验证码
 60             for (int i = 0; i < length; i++)
 61             {
 62                 validateNumberStr += validateNums[i].ToString();
 63             }
 64             return validateNumberStr;
 65         }
 66 
 67         /// <summary>
 68         /// 创建验证码的图片
 69         /// </summary>
 70         /// <param name="containsPage">要输出到的page对象</param>
 71         /// <param name="validateNum">验证码</param>
 72         public byte[] CreateValidateGraphic(string validateCode)
 73         {
 74             Bitmap image = new Bitmap((int) Math.Ceiling(validateCode.Length*12.0), 22);
 75             Graphics g = Graphics.FromImage(image);
 76             try
 77             {
 78                 //生成随机生成器
 79                 Random random = new Random();
 80                 //清空图片背景色
 81                 g.Clear(Color.White);
 82                 //画图片的干扰线
 83                 for (int i = 0; i < 25; i++)
 84                 {
 85                     int x1 = random.Next(image.Width);
 86                     int x2 = random.Next(image.Width);
 87                     int y1 = random.Next(image.Height);
 88                     int y2 = random.Next(image.Height);
 89                     g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2);
 90                 }
 91                 Font font = new Font("Arial", 12, (FontStyle.Bold | FontStyle.Italic));
 92                 LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height),
 93                     Color.Blue, Color.DarkRed, 1.2f, true);
 94                 g.DrawString(validateCode, font, brush, 3, 2);
 95                 //画图片的前景干扰点
 96                 for (int i = 0; i < 100; i++)
 97                 {
 98                     int x = random.Next(image.Width);
 99                     int y = random.Next(image.Height);
100                     image.SetPixel(x, y, Color.FromArgb(random.Next()));
101                 }
102                 //画图片的边框线
103                 g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);
104                 //保存图片数据
105                 MemoryStream stream = new MemoryStream();
106                 image.Save(stream, ImageFormat.Jpeg);
107                 //输出图片流
108                 return stream.ToArray();
109             }
110             finally
111             {
112                 g.Dispose();
113                 image.Dispose();
114             }
115         }
116 
117         /// <summary>
118         /// 得到验证码图片的长度
119         /// </summary>
120         /// <param name="validateNumLength">验证码的长度</param>
121         /// <returns></returns>
122         public static int GetImageWidth(int validateNumLength)
123         {
124             return (int) (validateNumLength*12.0);
125         }
126 
127         /// <summary>
128         /// 得到验证码的高度
129         /// </summary>
130         /// <returns></returns>
131         public static double GetImageHeight()
132         {
133             return 22.5;
134         }
135     }

 1  public static class HtmlExtensions
 2     {
 3         /// <summary>
 4         /// 生成验证码
 5         /// </summary>
 6         /// <param name="helper">当前View的HtmlHelper</param>
 7         /// <param name="urlHelper">当前View的UrlHelper</param>
 8         /// <returns>带验证码的Img</returns>
 9         public static MvcHtmlString GenerateCaptcha(this HtmlHelper helper, UrlHelper urlHelper)
10         {
11             var sb = new StringBuilder();
12             var builder = new TagBuilder("img");
13             builder.Attributes.Add("id", "captcha");
14             builder.Attributes.Add("style", "cursor:pointer");
15             builder.Attributes.Add("src", urlHelper.Action("GetCaptcha", "Common"));
16             builder.Attributes.Add("alt", "单击刷新验证码");
17             sb.AppendLine(builder.ToString(TagRenderMode.Normal));
18 
19             sb.AppendLine("<script>");
20             sb.AppendLine("$(function(){");
21             sb.AppendLine("$('#captcha').bind('click',function(){this.src='" +
22                           urlHelper.Action("GetCaptcha", "Common") + "?time='+(new Date()).getTime()})");
23             sb.AppendLine("})");
24             sb.AppendLine("</script>");
25 
26             return MvcHtmlString.Create(sb.ToString());
27         }
28 
29         /// <summary>
30         /// 生成验证码
31         /// </summary>
32         /// <typeparam name="TModel">Model</typeparam>
33         /// <typeparam name="TValue">Model的值</typeparam>
34         /// <param name="helper">当前View的HtmlHelper</param>
35         /// <param name="expression">Model属性的Lambda表达式</param>
36         /// <param name="urlHelper">当前View的UrlHelper</param>
37         /// <returns>封装好的label，textbox，带验证码的img</returns>
38         public static MvcHtmlString GenerateCaptcha<TModel, TValue>(this HtmlHelper<TModel> helper,
39             Expression<Func<TModel, TValue>> expression, UrlHelper urlHelper)
40         {
41             StringBuilder sb = new StringBuilder();
42             var label = helper.LabelFor(expression, new {}, "：");
43             var textbox = helper.TextBoxFor(expression);
44             var captcha = GenerateCaptcha(helper, urlHelper);
45             sb.AppendLine(label.ToHtmlString());
46             sb.AppendLine(textbox.ToHtmlString());
47             sb.AppendLine(captcha.ToHtmlString());
48 
49             return MvcHtmlString.Create(sb.ToString());
50         }
51     }

 1     public class CaptchaValidatorAttribute : ActionFilterAttribute
 2     {
 3         private const string CaptchaFormValue = "Captcha";
 4         public override void OnActionExecuting(ActionExecutingContext filterContext)
 5         {
 6             bool valid = false;
 7 
 8             foreach (var value in filterContext.HttpContext.Request.Form.AllKeys)
 9             {
10                 if (value.Contains(CaptchaFormValue))
11                 {
12                     valid = (string) filterContext.Controller.TempData["Captcha"] ==
13                             filterContext.HttpContext.Request.Form[value];
14                     break;
15                 }
16             }
17             filterContext.ActionParameters["captchaValid"] = valid;
18             base.OnActionExecuting(filterContext);
19         }
20     }