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ASP.NET中无刷新验证码实现

2008-07-12 08:28 507 查看

Default.aspx页面代码

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">

<head runat="server">

<title>Untitled Page</title>

<script>function show(im)

{

im.src="Default2.aspx?"+new Date;//注意这里的new Date一定要加上，否则只会生成一次验证码

}</script>

</head>

<body>

<form id="form1" runat="server">

<div>

<img src="Default2.aspx" onclick ="show(this)" />

</div>

</form>

</body>

</html>

[/code]

Default2.cs代码主要用来生成验证图片

using System;

using System.Data;

using System.Configuration;

using System.Collections;

using System.Web;

using System.Web.Security;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Web.UI.WebControls.WebParts;

using System.Web.UI.HtmlControls;

using System.Drawing;

using System.Drawing.Drawing2D;

public partial class Default2 : System.Web.UI.Page

{

protected void Page_Load(object sender, EventArgs e)

{

CreateCheckCodeImage(GenerateCheckCode());

}

/// <summary>

/// 生成随机校验码字符串

/// </summary>

/// <returns>生成的随机校验码字符串</returns>

public string GenerateCheckCode()

{

int number;

string strCode = string.Empty;

//随机数种子

Random radom = new Random();

for (int i = 0; i < 4; i++)

{

//随机的整数

number = radom.Next();

//字符从０－９，Ａ－Ｚ中随机产生，对应的ＡＳＣＩＩ码分别为48-57,65,90

number = number % 36;

if (number < 10)

{

number += 48;

}

else

{

number += 55;

}

strCode += ((char)number).ToString();

}

//在Cookie中保存校验码或Session中

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

return strCode;

}

/// <summary>

/// 根据校验码输出图片

/// </summary>

/// <param name="checkCode">产生的随机校验码</param>

public void CreateCheckCodeImage(string checkCode)

{

//若校验码为空，则直接返回

if (checkCode == null || checkCode.Trim() == string.Empty)

{

return;

}

//根据校验码的长度确定输出图片的长度

System.Drawing.Bitmap image = new System.Drawing.Bitmap((int)Math.Ceiling(decimal.Parse((checkCode.Length * 15)+"")), 20);

//创建ＧＲＡＰＨＩＣＳ对象

System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(image);

try

{

//生成随机数种子

Random random = new Random();

//清空图片背景色

g.Clear(System.Drawing.Color.White);

//画图片的背景噪音线１０条

for (int i = 0; i < 10; i++)

{

//噪音线起点坐标（x1,y1），终点坐标（x2,y2）

int x1 = random.Next(image.Width);

int x2 = random.Next(image.Width);

int y1 = random.Next(image.Height);

int y2 = random.Next(image.Height);

//用银色画出噪音线

g.DrawLine(new System.Drawing.Pen(System.Drawing.Color.Silver), x1, y1, x2, y2);

}

//输出图片中校验码的字体：１２号Arial,粗斜体

System.Drawing.Font font = new System.Drawing.Font("Arial", 12, (System.Drawing.FontStyle.Bold | System.Drawing.FontStyle.Italic));

//线形渐变画刷

System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new System.Drawing.Rectangle(0, 0, image.Width, image.Height), System.Drawing.Color.Blue, System.Drawing.Color.Purple, 1.2f, true);

g.DrawString(checkCode, font, brush, 2, 3);

//画图片的前景噪音点５０个

for (int i = 0; i < 50; i++)

{

int x = random.Next(image.Width);

int y = random.Next(image.Height);

image.SetPixel(x, y, System.Drawing.Color.FromArgb(random.Next()));

}

//画图片的边框线

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

//创建内存流用于输出图片

using (System.IO.MemoryStream ms = new System.IO.MemoryStream())

{

//图片格式指定为ＰＮＧ

image.Save(ms, System.Drawing.Imaging.ImageFormat.Png);

//清除缓冲区流中的所有输出

Response.ClearContent();

//输出流的ＨＴＴＰＭＩＭＥ类型设置为＂image/Png＂

Response.ContentType = "image/Png";

//输出图片的二进制流

Response.BinaryWrite(ms.ToArray());

}

}

finally

{

//释放 Ｂitmap 对象和 Ｇraphics 对象

g.Dispose();

image.Dispose();

}

}

}

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