ASP.NET 2.0 HttpHandler实现生成图片验证码(转)

来源：互联网发布：java websocketclient 编辑：程序博客网时间：2024/06/07 10:49

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>

publicclass 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">

<htmlxmlns="http://www.w3.org/1999/xhtml">

<headrunat="server">

<title>ImageValidateCode_HttpHandler</title>

</head>

<body>

<formid="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">

<TitleTextStyleBackColor="#507CD1" Font-Bold="True" Font-Size="0.9em" ForeColor="White"/>

<InstructionTextStyleFont-Italic="True" ForeColor="Black"/>

<LoginButtonStyleBackColor="White" BorderColor="#507CD1" BorderStyle="Solid" BorderWidth="1px"

Font-Names="Verdana" Font-Size="0.8em" ForeColor="#284E98"/>

<tr>

<tr>

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

background-color: #507cd1">

</tr>

<tr>

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

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

<asp:RequiredFieldValidatorID="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>

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

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

<asp:RequiredFieldValidatorID="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>

验证码:</td>

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

</tr>

<tr>

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

</tr>

<tr>

<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>