1. 处理程序文件 ValidateImageHandler.ashx代码如下
<%@ WebHandler Language="C#" Class="ValidateImageHandler" %>
using System;
using System.Web;
using System.Web.SessionState;
using System.Drawing;
using System.Drawing.Imaging;
using System.Text;
/// <summary>
/// ValidateImageHandler 生成网站验证码功能
/// </summary>
public class ValidateImageHandler : IHttpHandler, IRequiresSessionState
{
int intLength = 5; //长度
string strIdentify = "Identify"; //随机字串存储键值，以便存储到Session中
public ValidateImageHandler()
{
}
/// <summary>
/// 生成验证图片核心代码
/// </summary>
/// <param name="hc"></param>
public void ProcessRequest(HttpContext hc)
{
//设置输出流图片格式
hc.Response.ContentType = "image/gif";
Bitmap b = new Bitmap(200, 60);
Graphics g = Graphics.FromImage(b);
g.FillRectangle(new SolidBrush(Color.YellowGreen), 0, 0, 200, 60);
Font font = new Font(FontFamily.GenericSerif, 48, FontStyle.Bold, GraphicsUnit.Pixel);
Random r = new Random();
//合法随机显示字符列表
string strLetters = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890";
StringBuilder s = new StringBuilder();
//将随机生成的字符串绘制到图片上
for (int i = 0; i < intLength; i++)
{
s.Append(strLetters.Substring(r.Next(0, strLetters.Length - 1), 1));
g.DrawString(s[s.Length - 1].ToString(), font, new SolidBrush(Color.Blue), i * 38, r.Next(0, 15));
}
//生成干扰线条
Pen pen = new Pen(new SolidBrush(Color.Blue), 2);
for (int i = 0; i < 10; i++)
{
g.DrawLine(pen, new Point(r.Next(0, 199), r.Next(0, 59)), new Point(r.Next(0, 199), r.Next(0, 59)));
}
b.Save(hc.Response.OutputStream, ImageFormat.Gif);
hc.Session[strIdentify] = s.ToString(); //先保存在Session中，验证与用户输入是否一致
hc.Response.End();
}
/// <summary>
/// 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)
/// </summary>
public bool IsReusable
{
get
{
return true;
}
}
}
2.前台代码
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title>ImageValidateCode_HttpHandler</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<br />
<br />
<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">
<TitleTextStyle BackColor="#507CD1" Font-Bold="True" Font-Size="0.9em" ForeColor="White" />
<InstructionTextStyle Font-Italic="True" ForeColor="Black" />
<TextBoxStyle Font-Size="0.8em" />
<LoginButtonStyle BackColor="White" BorderColor="#507CD1" BorderStyle="Solid" BorderWidth="1px"
Font-Names="Verdana" Font-Size="0.8em" ForeColor="#284E98" />
<LayoutTemplate>
<table border="0" cellpadding="4" cellspacing="0" style="border-collapse: collapse">
<tr>
<td style="width: 292px">
<table border="0" cellpadding="0">
<tr>
<td align="center" colspan="2" style="font-weight: bold; font-size: 0.9em; color: white;
background-color: #507cd1">
登录</td>
</tr>
<tr>
<td align="left" style="width: 84px; height: 31px;">
<asp:Label ID="UserNameLabel" runat="server" AssociatedControlID="UserName">用户名:</asp:Label></td>
<td style="height: 31px; width: 215px;">
<asp:TextBox ID="UserName" runat="server" Font-Size="0.8em" Width="113px"></asp:TextBox>
<asp:RequiredFieldValidator ID="UserNameRequired" runat="server" ControlToValidate="UserName"
ErrorMessage="必须填写“用户名”。" ToolTip="必须填写“用户名”。" ValidationGroup="Login1">*</asp:RequiredFieldValidator>
</td>
</tr>
<tr>
<td align="left" style="width: 84px">
<asp:Label ID="PasswordLabel" runat="server" AssociatedControlID="Password">密码:</asp:Label></td>
<td style="width: 215px">
<asp:TextBox ID="Password" runat="server" Font-Size="0.8em" TextMode="Password"></asp:TextBox>
<asp:RequiredFieldValidator ID="PasswordRequired" runat="server" ControlToValidate="Password"
ErrorMessage="必须填写“密码”。" ToolTip="必须填写“密码”。" ValidationGroup="Login1">*</asp:RequiredFieldValidator>
</td>
</tr>
<tr>
<td style="width: 84px; height: 4px;" align="left">
验证码:</td>
<td valign="middle" style="height: 31px; width: 215px;" align="left">
<asp:TextBox ID="TextBox1" runat="server" Font-Size="0.8em" TextMode="Password"></asp:TextBox>
<img width="100px" height="25px" src="ValidateImageHandler.ashx" /></td>
</tr>
<tr>
<td align="left" colspan="2" style="color: red">
<asp:CheckBox ID="RememberMe" runat="server" Text="下次记住我。" /> </td>
</tr>
<tr>
<td align="right" colspan="2">
<asp:Button ID="LoginButton" runat="server" BackColor="White" BorderColor="#507CD1"
BorderStyle="Solid" BorderWidth="1px" CommandName="Login" Font-Names="Verdana"
Font-Size="0.8em" ForeColor="#284E98" Text="登录" ValidationGroup="Login1" />
</td>
</tr>
</table>
</td>
</tr>
</table>
</LayoutTemplate>
</asp:Login>
</div>
</form>
</body>
</html>
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