生成验证码

using System.IO;
using System.Drawing;
using System.Drawing.Imaging;
using System.Drawing.Drawing2D;

 

 

 

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();
       }

       Session["Code"] = checkCode;
      // 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();
   }
  }