HttpHandler生成随机码、验证码

html:

<img src="../../suiji.ashx" id="picsuiji" width="110" title="看不清楚换一张" />

juqery:

//以下代码可用js代替

$("#picsuiji").bind("click",function () {

$("#picsuiji").attr("src", "../../suiji.ashx?id=" + Math.random());

}

);

C#:

使用HttpHandler;

如果出现IE老是提示验证码错误，请参考另一篇文章 http://blog.csdn.net/liudong8510/article/details/8107014

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Drawing;
using System.Web.SessionState;  //为了用到session  继承了IReadOnlySessionState才能用context.Session否则回出错
namespace Vancl.SRM.Web
{
/// <summary>
/// Summary description for suiji
/// createUser:liud
/// createDate:2012-10-12
/// </summary>
public class suiji : IHttpHandler, IReadOnlySessionState
{

public void ProcessRequest(HttpContext context)
{
context.Response.Cache.SetCacheability(HttpCacheability.NoCache);
//特别注意，如不加，单击验证图片＇看不清换一张＇，无效果．
this.CreateCheckCodeImage(GenerateCheckCode(context, "Cookie"), context);

}

/// <summary>
/// 生成随机码图片
/// </summary>
/// <param name="checkCode">随机码</param>
/// <param name="context"></param>
private void CreateCheckCodeImage(string checkCode, HttpContext context)
{
if (checkCode == null || checkCode.Trim() == String.Empty)
return;
System.Drawing.Bitmap image = new System.Drawing.Bitmap((int)Math.Ceiling((checkCode.Length * 12.5)), 22);
Graphics g = Graphics.FromImage(image);

try
{
Random random = new Random(); // //生成随机生成器
g.Clear(Color.White);   //清空图片背景色
for (int i = 0; i < 25; i++)   //画图片的背景噪音线
{
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++)  //画图片的前景噪音点
{
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); //画图片的边框线
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();
}

}

/// <summary>
/// 生成随机码
/// </summary>
/// <param name="context"></param>
/// <param name="type">如果随机码保存在Cookie里，那么填写Cookie ； 如果保存在Session里，那么填写Session</param>
/// <returns></returns>
private string GenerateCheckCode(HttpContext context, string type)
{
int number;
char code;
string checkCode = String.Empty;
System.Random random = new Random();
for (int i = 0; i < 4; i++)
{
number = random.Next();

if (number % 2 == 0)
code = (char)('0' + (char)(number % 10));
else if (number % 3 == 0)
code = (char)('A' + (char)(number % 26));
else
code = (char)('a' + (char)(number % 26));
checkCode += code.ToString();
}
if (type == "Cookie")
{
HttpCookie httpCookie = new HttpCookie("CheckCode");
//httpCookie.Domain = "";可以指定域
httpCookie.Expires = DateTime.Now.AddDays(2);
httpCookie.Value = checkCode;
context.Response.Cookies.Add(httpCookie);//存到Cookie里．
}
else if (type == "Session")
{
context.Session["CheckCode"] = checkCode;  //存到Seesion里．
}

return checkCode;
}

public bool IsReusable
{
get
{
return false;
}
}
}

}