c#验证码

(1)

 protected void Page_Load(object sender, EventArgs e)
    {
        // 创建一个包含随机内容的验证码文本

        System.Random rand = new Random();

        int len = rand.Next(4, 6);

        char[] chars = "周维强周乐兵唐伟0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ".ToCharArray();

        System.Text.StringBuilder myStr = new System.Text.StringBuilder();

        for (int iCount = 0; iCount < len; iCount++) { myStr.Append(chars[rand.Next(chars.Length)]); }

        string text = myStr.ToString();

        // 保存验证码到 session 中以便其他模块使用:

        this.Session["checkcode"] = text;

        Size ImageSize = Size.Empty;

        Font myFont = new Font("MS Sans Serif", 20);

        // 计算验证码图片大小

        using (Bitmap bmp = new Bitmap(10, 10))
        {

            using (Graphics g = Graphics.FromImage(bmp))
            {
                SizeF size = g.MeasureString(text, myFont, 10000);

                ImageSize.Width = (int)size.Width + 8;

                ImageSize.Height = (int)size.Height + 8;
            }

        }

        // 创建验证码图片

        using (Bitmap bmp = new Bitmap(ImageSize.Width, ImageSize.Height))
        {

            // 绘制验证码文本

            using (Graphics g = Graphics.FromImage(bmp))
            {

                g.Clear(Color.White);

                using (StringFormat f = new StringFormat())
                {

                    f.Alignment = StringAlignment.Near;

                    f.LineAlignment = StringAlignment.Center;

                    f.FormatFlags = StringFormatFlags.NoWrap;

                    g.DrawString(text, myFont, Brushes.Black, new RectangleF(0, 0, ImageSize.Width, ImageSize.Height), f);

                }

            }

            // 制造噪声 杂点面积占图片面积的 30%

            int num = ImageSize.Width * ImageSize.Height * 30 / 100;

            for (int iCount = 0; iCount < num; iCount++)
            {

                // 在随机的位置使用随机的颜色设置图片的像素

                int x = rand.Next(ImageSize.Width);

                int y = rand.Next(ImageSize.Height);

                int r = rand.Next(255);

                int g = rand.Next(255);

                int b = rand.Next(255);

                Color c = Color.FromArgb(r, g, b);

                bmp.SetPixel(x, y, c);

            }

            // 输出图片

            System.IO.MemoryStream ms = new System.IO.MemoryStream();

            bmp.Save(ms, System.Drawing.Imaging.ImageFormat.Png);

            this.Response.ContentType = "image/png";

            ms.WriteTo(this.Response.OutputStream);

            ms.Close();
        }

        //using

        myFont.Dispose();

    }

    /// 检查指定的文本是否匹配验证码  /// 要判断的文本 /// 是否匹配

    public static bool CheckCode(string text)
    {

        string txt = System.Web.HttpContext.Current.Session["checkcode"] as string;

        return text == txt;

    }

 

 

(2)

* Copyright all(c) 2005 ZhongFeng, http://blog.csdn.net/SW515 */
 public 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();
   }
  }
 }