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ASP.NET 2.0 HttpHandler实现生成图片验证码(示例代码下载)

2015-03-21 10:09 851 查看
学习整理了一下

(一).功能

用HttpHandler实现图片验证码



(二).代码如下

1. 处理程序文件 ValidateImageHandler.ashx代码如下

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 生成网站验证码功能

12 /// </summary>

13 public class ValidateImageHandler : IHttpHandler, IRequiresSessionState

14 {

15 int intLength = 5; //长度

16 string strIdentify = "Identify"; //随机字串存储键值,以便存储到Session中

17 public ValidateImageHandler()

18 {

19 }

20

21 /// <summary>

22 /// 生成验证图片核心代码

23 /// </summary>

24 /// <param name="hc"></param>

25 public void ProcessRequest(HttpContext hc)

26 {

27 //设置输出流图片格式

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 //合法随机显示字符列表

37 string strLetters = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890";

38 StringBuilder s = new StringBuilder();

39

40 //将随机生成的字符串绘制到图片上

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 //生成干扰线条

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(); //先保存在Session中,验证与用户输入是否一致

55 hc.Response.End();

56

57 }

58

59 /// <summary>

60 /// 表示此类实例是否可以被多个请求共用(重用可以提高性能)

61 /// </summary>

62 public bool IsReusable

63 {

64 get

65 {

66 return true;

67 }

68 }

69 }

70

2. 前台页面代码

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 <LayoutTemplate>

8 <table border="0" cellpadding="4" cellspacing="0" style="border-collapse: collapse">

9 <tr>

10 <td style="width: 292px">

11 <table border="0" cellpadding="0">

12 <tr>

13 <td align="center" colspan="2" style="font-weight: bold; font-size: 0.9em; color: white;

14 background-color: #507cd1">

15 登录</td>

16 </tr>

17 <tr>

18 <td align="left" style="width: 84px; height: 31px;">

19 <asp:Label ID="UserNameLabel" runat="server" AssociatedControlID="UserName">用户名:</asp:Label></td>

20 <td style="height: 31px; width: 215px;">

21 <asp:TextBox ID="UserName" runat="server" Font-Size="0.8em" Width="113px"></asp:TextBox>

22 <asp:RequiredFieldValidator ID="UserNameRequired" runat="server" ControlToValidate="UserName"

23 ErrorMessage="必须填写“用户名”。" ToolTip="必须填写“用户名”。" ValidationGroup="Login1">*</asp:RequiredFieldValidator>

24 </td>

25 </tr>

26 <tr>

27 <td align="left" style="width: 84px">

28 <asp:Label ID="PasswordLabel" runat="server" AssociatedControlID="Password">密码:</asp:Label></td>

29 <td style="width: 215px">

30 <asp:TextBox ID="Password" runat="server" Font-Size="0.8em" TextMode="Password"></asp:TextBox>

31 <asp:RequiredFieldValidator ID="PasswordRequired" runat="server" ControlToValidate="Password"

32 ErrorMessage="必须填写“密码”。" ToolTip="必须填写“密码”。" ValidationGroup="Login1">*</asp:RequiredFieldValidator>

33 </td>

34 </tr>

35 <tr>

36 <td style="width: 84px; height: 4px;" align="left">

37 验证码:</td>

38 <td valign="middle" style="height: 31px; width: 215px;" align="left">

39 <asp:TextBox ID="TextBox1" runat="server" Font-Size="0.8em" TextMode="Password"></asp:TextBox> 

40
[align=left] <img width="100px" height="25px" src="ValidateImageHandler.ashx"/>[/align]
[align=left][/align]
</td>

41 </tr>

42 <tr>

43 <td align="left" colspan="2" style="color: red">

44 <asp:CheckBox ID="RememberMe" runat="server" Text="下次记住我。" /> </td>

45 </tr>

46 <tr>

47 <td align="right" colspan="2">

48 <asp:Button ID="LoginButton" runat="server" BackColor="White" BorderColor="#507CD1"

49 BorderStyle="Solid" BorderWidth="1px" CommandName="Login" Font-Names="Verdana"

50 Font-Size="0.8em" ForeColor="#284E98" Text="登录" ValidationGroup="Login1" />

51 </td>

52 </tr>

53 </table>

54 </td>

55 </tr>

56 </table>

57 </LayoutTemplate>

58

59 </asp:Login>

60

3.这里因为使用的是默认 *.asah处理文件类型,在machine.config文件中已经有此类型的默认注册,
因为这里不需要注册

1 <httpHandlers>

2 <add verb="*" path="*.asah" type="System.Web.UI.SimpleHandlerFactory" />

3 </httpHandlers>

4

注意:

1.再注册一下也不会出错,会覆盖machine.config文件配置

2.如果在同一个配置文件中注册多次,默认后者也会覆盖前者.

3.如果其它格式(系统默认没有注册)的,务必要在Web.config文件中注册一下.

(三).示例代码下载

http://www.cnblogs.com/Files/ChengKing/ValidateImageHttpHandler.rar
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