C#生成随机验证码例子

C#生成随机验证码例子：

前端：

  <tr>
           <td width="24%" height="" align="center" valign="top">
               验证码：</td>
           <td valign="top" width="37%" align="left">
              <input type="text" name="txtCode" id="txtvalidateCode"/><a href="javascript:void(0)" id="valiateCode"><img src="/ashx/ValidateCode.ashx?id=1" id="imgCode" /></a><span style="font-size:14px;color:red " id="userCodeMsg"></span></td>
         </tr>

给验证码图片绑定单击事件：

 $("#valiateCode").click(function () {
  　　$("#imgCode").attr("src",$("#imgCode").attr("src")+1);
 });

后台生成验证码图片代码：

ValidateCode.ashx

 <%@ WebHandler Language="C#" Class="ValidateCode" %>

 using System;
 using System.Web;
 using System.Drawing;
 using System.Web.SessionState;

 public class ValidateCode : IHttpHandler, IRequiresSessionState
 {
     HttpContext context;
     public void ProcessRequest (HttpContext context1) {
         this.context = context1;
         CreateCheckCodeImage(GenerateCheckCode());
     }

     private string GenerateCheckCode()
     {
         int number;
         char code;
         string checkCode = String.Empty;

         System.Random random = new Random();

         for (int i = ; i < ; i++)
         {
             number = random.Next();

             if (number %  == )
                 code = (char)('' + (char)(number % ));
             else
                 code = (char)('' + (char)(number % ));
             //code = (char)('A' + (char)(number % 26));

             checkCode += code.ToString();
         }

         //添加Session值
         context.Session.Add("vCode", checkCode);
         return checkCode;
     }

     private void CreateCheckCodeImage(string checkCode)
     {
         if (checkCode == null || checkCode.Trim() == String.Empty)
             return;

         System.Drawing.Bitmap image = new System.Drawing.Bitmap((int)Math.Ceiling((checkCode.Length * 12.5)), );
         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);

             //画图片的背景噪音线
             for (int i = ; i < ; 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 System.Drawing.Font("Arial", , (System.Drawing.FontStyle.Bold | System.Drawing.FontStyle.Italic));
             System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(, , image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2f, true);
             g.DrawString(checkCode, font, brush, , );

             //画图片的前景噪音点
             for (int i = ; i < ; 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), , , image.Width - , image.Height - );

             System.IO.MemoryStream ms = new System.IO.MemoryStream();
             image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
             context.Response.ClearContent();
             context.Response.ContentType = "image/Gif";
             context.Response.BinaryWrite(ms.ToArray());
         }
         finally
         {
             g.Dispose();
             image.Dispose();
         }
     }

     public bool IsReusable {
         get {
             return false;
         }
     }

 }

验证码效果：