验证码代码片段

Server-side Code:

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

using System;
using System.Web;
using System.Data;
using System.Web.Security;
using System.Data.SqlClient;
using System.Drawing;

public class Handler : IHttpHandler {
    
    public void ProcessRequest (HttpContext context) 
    {
        string requestType = context.Request["type"];
        switch (requestType)
        {
            case "Captcha": CreateCheckCodeImage(GenerateCheckCode(context), context); break;
        }      
    }
    
    private string GenerateCheckCode(HttpContext context)
    {
        int number;
        char code;
        string checkCode = String.Empty;

        System.Random random = new Random();

        for (int i = 0; i < 5; i++)
        {
            number = random.Next();

            if (number % 2 == 0)
                code = (char)('0' + (char)(number % 10));
            else
                code = (char)('A' + (char)(number % 26));

            checkCode += code.ToString();
        }

        context.Response.Cookies.Add(new HttpCookie("CheckCode", checkCode));

        return checkCode;
    }

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

        Bitmap image = new Bitmap((int)Math.Ceiling((checkCode.Length * 12.5)), 22);
        Graphics g = Graphics.FromImage(image);

        try
        {
            Random random = new Random();

            g.Clear(Color.White);

            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 System.Drawing.Font("Arial", 12, (System.Drawing.FontStyle.Bold | System.Drawing.FontStyle.Italic));
            System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2f, true);
            g.DrawString(checkCode, font, brush, 2, 2);

            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()));
            }

            g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);

            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;
        }
    }
}

Client-side:
//Client-side code
This is an ASPX Page.
<html>
	<body>
		 <td>
		 	<img id="imgValidation" src="CaptchaHandler.ashx?type=Captcha" onclick="this.src='CaptchaHandler.ashx?type=Captcha&id='+Math.random()" 
			alt="Click to change picture" style="cursor:pointer" />
		</td>
		<td>
                 <asp:TextBox ID="txtValidationKey" runat="server" Width="95px" />
            </td>
	</body>
</html>
posted @ 2010-05-25 09:31  lp123  阅读(234)  评论(0)  编辑  收藏  举报