初学验证码的使用 - 超少

公告

先照着网上找的代码做了一个Validcode.aspx.cs页，然后在另一个页面上拉了一个TEXTBOX控件，在后面加了一个 <iframe src="Validcode.aspx" height="25" width="100" scrolling="no" frameborder="0" marginwidth="0" marginheight="0" style="width: 60px; height: 22px"></iframe>
浏览时就可以显示出验证码来了
然后我在后台加代码

if (this.TextBox1.Text == Session["ValidCode"].ToString()) { Response.Write("验证成功！"); }

else { Response.Write("验证失败！"); }

出现错误：未将对象引用设置到对象的实例。

然后把代码去掉，又在页面上加了<IMG src="Validcode.aspx"/>

奇怪的事发生了，两张图片竟然显示不一样的验证码！！！到底要添哪一个？？？

我的前台页面

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

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

</head>

<body>

<div>

<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>

marginwidth="0" marginheight="0" style="width: 60px; height: 22px"></iframe>

</div>

</form>

</body>

</html>

Validcode.aspx.cs页

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.Text;

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

{

private void Page_Load(object sender, System.EventArgs e)

{

this.CreateCheckCodeImage(GenerateCheckCode());

}

Web 窗体设计器生成的代码

private string GenerateCheckCode()

{

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();

}

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

Session["ValidCode"] = 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)), 22);

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 = 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);

//画图片的前景噪音点

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()));

}

//画图片的边框线

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);

Response.ClearContent();

Response.ContentType = "image/Gif";

Response.BinaryWrite(ms.ToArray());

}

finally

{

g.Dispose();

image.Dispose();

}

posted on 2007-09-21 13:19 超少阅读(272) 评论(3) 收藏举报

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