验证码

using  System;
using  System.Collections;
using  System.Configuration;
using  System.Data;
using  System.Linq;
using  System.Web;
using  System.Web.Security;
using  System.Web.UI;
using  System.Web.UI.HtmlControls;
using  System.Web.UI.WebControls;
using  System.Web.UI.WebControls.WebParts;
using  System.Xml.Linq;
using  System.Drawing;

public   partial   class  ValidateCode : System.Web.UI.Page
{
     private   void  Page_Load( object  sender, System.EventArgs e)
    {
         this .CreateCheckCodeImage(GenerateCheckCode());
    }

     #region  Web 窗体设计器生成的代码
     override   protected   void  OnInit(EventArgs e)
    {
         //
         //  CODEGEN: 该调用是 ASP.NET Web 窗体设计器所必需的。
         //
        InitializeComponent();
         base .OnInit(e);
    }

     ///   <summary>
     ///  设计器支持所需的方法 - 不要使用代码编辑器修改
     ///  此方法的内容。
     ///   </summary>
     private   void  InitializeComponent()
    {
         this .Load  +=   new  System.EventHandler( this .Page_Load);
    }
     #endregion

     private   string  GenerateCheckCode()
    {
         int  number;
         char  code;
         string  checkCode  =  String.Empty;

        System.Random random  =   new  Random();

         for  ( int  i  =   0 ; i  <   5 ; i ++ )
        {
            number  =  random.Next();

             if  (number  %   2   ==   0 )
                code  =  ( char )( ' 0 '   +  ( char )(number  %   10 ));
             else
                code  =  ( char )( ' A '   +  ( char )(number  %   26 ));

            checkCode  +=  code.ToString();
        }

        Response.Cookies.Add( new  HttpCookie( " CheckCode " , checkCode));

         return  checkCode;
    }

     private   void  CreateCheckCodeImage( string  checkCode)
    {
         if  (checkCode  ==   null   ||  checkCode.Trim()  ==  String.Empty)
             return ;

        System.Drawing.Bitmap image  =   new  System.Drawing.Bitmap(( int )Math.Ceiling((checkCode.Length  *   12.5 )),  22 );
        Graphics g  =  Graphics.FromImage(image);

         try
        {
             // 生成随机生成器
            Random random  =   new  Random();

             // 清空图片背景色
            g.Clear(Color.White);

             // 画图片的背景噪音线
             for  ( int  i  =   0 ; i  <   25 ; i ++ )
            {
                 int  x1  =  random.Next(image.Width);
                 int  x2  =  random.Next(image.Width);
                 int  y1  =  random.Next(image.Height);
                 int  y2  =  random.Next(image.Height);

                g.DrawLine( new  Pen(Color.Silver), x1, y1, x2, y2);
            }

            Font font  =   new  System.Drawing.Font( " Arial " ,  12 , (System.Drawing.FontStyle.Bold  |  System.Drawing.FontStyle.Italic));
            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 );
            g.DrawString(checkCode, font, brush,  2 ,  2 );

             // 画图片的前景噪音点
             for  ( int  i  =   0 ; i  <   100 ; i ++ )
            {
                 int  x  =  random.Next(image.Width);
                 int  y  =  random.Next(image.Height);

                image.SetPixel(x, y, Color.FromArgb(random.Next()));
            }

             // 画图片的边框线
            g.DrawRectangle( new  Pen(Color.Silver),  0 ,  0 , image.Width  -   1 , image.Height  -   1 );

            System.IO.MemoryStream ms  =   new  System.IO.MemoryStream();
            image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
            Response.ClearContent();
            Response.ContentType  =   " image/Gif " ;
            Response.BinaryWrite(ms.ToArray());
        }
         finally
        {
            g.Dispose();
            image.Dispose();
        }
    }

    }
    
 

< div >
         < asp:Image Runat = " server "  ID = " ImageCheck "  ImageUrl = " ValidateCode.aspx " ></ asp:Image >
         < asp:TextBox ID = " txtCheckCode "  runat = " server " ></ asp:TextBox >
         < asp:Button ID = " Button1 "  runat = " server "  Text = " Button "  onclick = " Button1_Click "   />
         < br />
         < asp:Label ID = " lblMessage "  runat = " server "  Text = "" ></ asp:Label >
     </ div >

protected   void  Button1_Click( object  sender, EventArgs e)
    {
        lblMessage.Text  =   "" ;
         if (Request.Cookies[ " CheckCode " ]  ==   null )
        {
            lblMessage.Text  =   " 您的浏览器设置已被禁用 Cookies，您必须设置浏览器允许使用 Cookies 选项后才能使用本系统。 " ;
            lblMessage.Visible  =   true ;
              return ;
        }

         if  (String.Compare(Request.Cookies[ " CheckCode " ].Value, txtCheckCode.Text,  true )  !=   0 )
        {
            lblMessage.Text  =   " 验证码错误，请输入正确的验证码。 " ;
            lblMessage.Visible  =   true ;
             return ;
        }
         else
        {
            lblMessage.Text  =   " 验证通过 " ;
        }
    }