最近小舖有人提到圖片驗證碼的文章.....
一般在輸入表單裡加上圖片驗證碼是不錯的...可以防止一些攻擊....
一般圖片驗證碼都是寫在aspx裡,而且都是利用cookie儲存....
小弟用一個簡單的範例,,介紹如何將圖片驗碼碼寫在handle裡,,並且將驗證碼儲存在session裡....
此範例,包含cookie與session的用法..,驗證碼的程式是參考網路上別人寫好的code...c#範例
ValidateCode.ashx
001 
<%@ WebHandler Language=
"C#" Class=
"ValidateCode" %>
002
003 
<%@ WebHandler Language=
"C#" Class=
"ValidateCode" %>
004
005 using ...System;
006 using System.Web;
007 using System.Drawing;
008 
using System.Web.SessionState;
009
010 public class ValidateCode : IHttpHandler, IRequiresSessionState
011 ...{
012 
013 public void ProcessRequest(HttpContext context)
014 
...{
015 CreateCheckCodeImage(GenerateCheckCode(context), context);
016 
}
017
018 private string GenerateCheckCode(HttpContext context)
019 ...{
020 int number;
021 char code;
022 string checkCode = String.Empty;
023
024 System.Random random = new Random();
025
026 for (int i = 0; i < 5; i++)
027 ...{
028 number = random.Next();
029
030 if (number % 2 == 0)
031 code = (char)('0' + (char)(number % 10));
032 else
033 code = (char)('A' + (char)(number % 26));
034
035 checkCode += code.ToString();
036 }
037
038 //儲存在cookie
039 context.Response.Cookies.Add(new HttpCookie("CheckCode", checkCode));
040
041 //儲存在session
042 context.Session["CheckCode"] = checkCode;
043
044 return checkCode;
045 }
046
047 private void CreateCheckCodeImage(string checkCode, HttpContext context)
048 ...{
049 if (checkCode == null || checkCode.Trim() == String.Empty)
050 return;
051
052 System.Drawing.Bitmap image = new System.Drawing.Bitmap((int)Math.Ceiling((checkCode.Length * 12.5)), 22);
053 Graphics g = Graphics.FromImage(image);
054
055 try
056 ...{
057 //生成?机生成器
058 Random random = new Random();
059
060 //清空?片背景色
061 g.Clear(Color.White);
062
063 //??片的背景噪音?
064 for (int i = 0; i < 25; i++)
065 ...{
066 int x1 = random.Next(image.Width);
067 int x2 = random.Next(image.Width);
068 int y1 = random.Next(image.Height);
069 int y2 = random.Next(image.Height);
070
071 g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2);
072 }
073
074 Font font = new System.Drawing.Font("Arial", 12, (System.Drawing.FontStyle.Bold | System.Drawing.FontStyle.Italic));
075 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);
076 g.DrawString(checkCode, font, brush, 2, 2);
077
078 //??片的前景噪音?
079 for (int i = 0; i < 100; i++)
080 ...{
081 int x = random.Next(image.Width);
082 int y = random.Next(image.Height);
083
084 image.SetPixel(x, y, Color.FromArgb(random.Next()));
085 }
086
087 //??片的?框?
088 g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);
089
090 System.IO.MemoryStream ms = new System.IO.MemoryStream();
091 image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
092 context.Response.ClearContent();
093 context.Response.ContentType = "image/Gif";
094 context.Response.BinaryWrite(ms.ToArray());
095 }
096 finally
097 ...{
098 g.Dispose();
099 image.Dispose();
100 }
101 }
102
103 public bool IsReusable
104 ...{
105 get
106 ...{
107 return false;
108 }
109 }
110
111 }
112
CheckCode.aspx
01 <%@ Page Language="C#" AutoEventWireup="true" CodeFile="CheckCode.aspx.cs" Inherits="CheckCode" %>
02
03 <%@ Register Src="ValidateCode.ascx" TagName="ValidateCode" TagPrefix="uc1" %>
04 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
05 <html xmlns="http://www.w3.org/1999/xhtml">
06 <head id="Head1" runat="server">
07 <title>CheckCode</title>
08 </head>
09 <body>
10 <form id="form1" runat="server">
11 <div>
12 <asp:Image ID="Image1" runat="server" ImageUrl="ValidateCode.ashx" /><br />
13 <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
14 <br />
15 <asp:Button ID="Button1" runat="server" Text="CheckCode(cookie)" OnClick="Button1_Click" /><br />
16 <asp:Button ID="Button2" runat="server" OnClick="Button2_Click" Text="CheckCode(Session)" /></div>
17 </form>
18 </body>
19 </html>
20
CheckCode.aspx.cs
執行結果：
參考網址：http://www.cnblogs.com/gwazy/archive/2005/04/18/139510.html
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2008/3/16 23:42|
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