.net(c#)验证码

前面发表过一个验证码，但感觉不好，今天在发表一个，带噪点的，看起来更专业一点。

前台CheckCode.aspx

<% @ Page language = " c# "  Inherits = " Guestbook.CheckCode "  CodeFile = " CheckCode.aspx.cs "   %>
<! DOCTYPE HTML PUBLIC  " -//W3C//DTD HTML 4.0 Transitional//EN "   >
< HTML >
     < HEAD >
         < title > CheckCode </ title >
         < meta name = " GENERATOR "  Content = " Microsoft Visual Studio .NET 7.1 " >
         < meta name = " CODE_LANGUAGE "  Content = " C# " >
         < meta name = " vs_defaultClientScript "  content = " JavaScript " >
         < meta name = " vs_targetSchema "  content = " http://schemas.microsoft.com/intellisense/ie5 " >
     </ HEAD >
     < body >
         < form id = " Form1 "  method = " post "  runat = " server " >
             < FONT face = " 宋体 " ></ FONT >
         </ form >
     </ body >
</ HTML >

 后台CheckCode.aspx.cs

using  System;
using  System.Collections;
using  System.ComponentModel;
using  System.Data;
using  System.Drawing;
using  System.Web;
using  System.Web.SessionState;
using  System.Web.UI;
using  System.Web.UI.WebControls;
using  System.Web.UI.HtmlControls;



namespace  Guestbook
... {
    /**//// <summary>
    /// 页面检查生成的Session["CheckCode"]
    /// </summary>
    public partial class CheckCode : System.Web.UI.Page
    ...{

            protected void Page_Load(object sender, System.EventArgs e)
            ...{
                this.CreateCheckCodeImage(GenerateCheckCode());
            }

        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));
            Session["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();
            }
        }


    }
}

-----------------------------------

调用页面Default.aspx 

           < tr >
             < td align = " center "  height = " 30 "   > 验证码 </ td >
             < td style = " height: 30px " >< input name = " Txt_imgCode "  type = " text "  id = " Txt_imgCode "  size = " 5 "  maxlength = " 5 "   tabindex = " 3 " />
                 < img id = " CodeImg "  onclick = " this.src='CheckCode.aspx' "  src = " CheckCode.aspx "   />
                 < input onclick = " document.getElementById('CodeImg').src='CheckCode.aspx?tmp='+Math.random() "
                            type = " button "  value = " 验证码 "  name = " Btn_Re "   /></ td >
           </ tr >

之后在后台对Session["CheckCode"].ToString().ToLower()进行验证就行了，来判断验证码是否正确。

希望对大家有帮助