學習整理了一下 (一).功能 用HttpHandler實現圖片驗證碼 (二).代碼如下 1. 處理常式檔案 ValidateImageHandler.ashx代碼如下 1 <% @ WebHandler Language = " C# " Class = " ValidateImageHandler " %>
2
3 using System;
4 using System.Web;
5 using System.Web.SessionState;
6 using System.Drawing;
7 using System.Drawing.Imaging;
8 using System.Text;
9
10 /// <summary>
11 /// ValidateImageHandler 產生網站驗證碼功能
12 /// </summary>
13 public class ValidateImageHandler : IHttpHandler, IRequiresSessionState
14 {
15 int intLength = 5 ; // 長度
16 string strIdentify = " Identify " ; // 隨機字串儲存索引值，以便儲存到Session中
17 public ValidateImageHandler()
18 {
19 }
20
21 /// <summary>
22 /// 產生驗證圖片核心代碼
23 /// </summary>
24 /// <param name="hc"></param>
25 public void ProcessRequest(HttpContext hc)
26 {
27 // 設定輸出資料流圖片格式
28 hc.Response.ContentType = " image/gif " ;
29
30 Bitmap b = new Bitmap( 200 , 60 );
31 Graphics g = Graphics.FromImage(b);
32 g.FillRectangle( new SolidBrush(Color.YellowGreen), 0 , 0 , 200 , 60 );
33 Font font = new Font(FontFamily.GenericSerif, 48 , FontStyle.Bold, GraphicsUnit.Pixel);
34 Random r = new Random();
35
36 // 合法隨機顯示字元列表
37 string strLetters = " abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890 " ;
38 StringBuilder s = new StringBuilder();
39
40 // 將隨機產生的字串繪製到圖片上
41 for ( int i = 0 ; i < intLength; i ++ )
42 {
43 s.Append(strLetters.Substring(r.Next( 0 , strLetters.Length - 1 ), 1 ));
44 g.DrawString(s[s.Length - 1 ].ToString(), font, new SolidBrush(Color.Blue), i * 38 , r.Next( 0 , 15 ));
45 }
46
47 // 產生幹擾線條
48 Pen pen = new Pen( new SolidBrush(Color.Blue), 2 );
49 for ( int i = 0 ; i < 10 ; i ++ )
50 {
51 g.DrawLine(pen, new Point(r.Next( 0 , 199 ), r.Next( 0 , 59 )), new Point(r.Next( 0 , 199 ), r.Next( 0 , 59 )));
52 }
53 b.Save(hc.Response.OutputStream, ImageFormat.Gif);
54 hc.Session[strIdentify] = s.ToString(); // 先儲存在Session中，驗證與使用者輸入是否一致
55 hc.Response.End();
56
57 }
58
59 /// <summary>
60 /// 表示此類執行個體是否可以被多個請求共用(重用可以提高效能)
61 /// </summary>
62 public bool IsReusable
63 {
64 get
65 {
66 return true ;
67 }
68 }
69 }
70
2. 前台頁面代碼 1 < asp:Login ID = " Login1 " runat = " server " BackColor = " #EFF3FB " BorderColor = " #B5C7DE " BorderPadding = " 4 " BorderStyle = " Solid " BorderWidth = " 1px " Font - Names = " Verdana " Font - Size = " 0.8em " ForeColor = " #333333 " OnAuthenticate = " Login1_Authenticate " >
2 < TitleTextStyle BackColor = " #507CD1 " Font - Bold = " True " Font - Size = " 0.9em " ForeColor = " White " />
3 < InstructionTextStyle Font - Italic = " True " ForeColor = " Black " />
4 < TextBoxStyle Font - Size = " 0.8em " />
5 < LoginButtonStyle BackColor = " White " BorderColor = " #507CD1 " BorderStyle = " Solid " BorderWidth = " 1px "
6 Font - Names = " Verdana " Font - Size = " 0.8em " ForeColor = " #284E98 " />
7 &nbs
