ASP.NET產生圖形驗證碼的泛型處理常式設計_CAPTCHA

前台

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<script type="text/javascript"> function reloadcode() { document.getElementById("Image1").src = "~/handler/CaptchaCreator/CaptchaHandler.ashx"; return false; } </script>

.ashx.cs程式

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<%@ WebHandler Language="C#" Class="CaptchaHandler" %> using System; using System.Web; using System.Web.SessionState; using System.Collections.Generic; using System.Drawing; using System.Drawing.Imaging; using System.Drawing.Drawing2D; public class CaptchaHandler : IHttpHandler, IRequiresSessionState { public void ProcessRequest(HttpContext context) { int DigitCount = 6; string str_rnd_code = GetRandomCode(DigitCount); context.Session["ValidatePictureCode"] = str_rnd_code; System.Drawing.Image image = CreateCaptchaImage(str_rnd_code); System.IO.MemoryStream ms = new System.IO.MemoryStream(); image.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg); context.Response.Clear(); context.Response.ContentType = "image/jpeg"; context.Response.BinaryWrite(ms.ToArray()); ms.Close(); } private string GetRandomCode(int digit_count) { string str_code_result = ""; Random rand = new Random(Guid.NewGuid().GetHashCode()); List<string> lsChrSet = new List<string>(); List<string> lsNeedAvoid = new List<string>(new[] { "O", "o", "l", "I" });//保留數字0、1排除容易混淆的大寫O小寫o跟大寫I小寫L for (int i = 0; i <= 35; i++) { if (i < 10) { int ascii_code = 48 + i;//0~9 : 48 ~ 57 string chr_digit_result = ((char)(ascii_code)).ToString(); //Console.WriteLine(string.Format("Ascii code (digit):{0}->{1}", ascii_code, chr_digit_result)); lsChrSet.Add(chr_digit_result); } else { int new_idx = i - 10; int ascii_code = 97 + new_idx;//a~z : 97 ~ 122 string chr_result_lowercase = ((char)(ascii_code)).ToString(); //Console.WriteLine(string.Format("Ascii code (lowercase):{0}->{1}", ascii_code, chr_result_lowercase)); if (!lsNeedAvoid.Contains(chr_result_lowercase)) lsChrSet.Add(chr_result_lowercase); string chr_result_uppercase = ((char)(ascii_code - 32)).ToString();//A~Z : 65 ~ 90 //Console.WriteLine(string.Format("Ascii code (uppercase):{0}->{1}", ascii_code - 32, chr_result_uppercase)); if (!lsNeedAvoid.Contains(chr_result_uppercase)) lsChrSet.Add(chr_result_uppercase); } } for (int idx_digit = 0; idx_digit < digit_count; idx_digit++) { int rndIdx = rand.Next(lsChrSet.Count); str_code_result += lsChrSet[rndIdx]; } return str_code_result; } private System.Drawing.Image CreateCaptchaImage(string str_rnd_code) { System.Drawing.Bitmap image = new System.Drawing.Bitmap((str_rnd_code.Length * 14), 28); System.Drawing.Graphics g = Graphics.FromImage(image); Random random = new Random(Guid.NewGuid().GetHashCode()); int int_Red = 255; int int_Green = 255; int int_Blue = 255; int int_bkack = random.Next(240, 255); g.Clear(Color.FromArgb(int_Red, int_Green, int_Blue)); Rectangle rect = new Rectangle(0, 0, image.Width, image.Height); Brush brushBack = new LinearGradientBrush(rect, Color.FromArgb(int_bkack, int_bkack, int_bkack), Color.FromArgb(255, 255, 255), 255);// 新增黑白漸層 g.FillRectangle(brushBack, rect); for (int i = 0; i < str_rnd_code.Length; i++) { Color wc = Color.FromArgb(0, 0, 0); int y = random.Next(0, 6); Font font = new System.Drawing.Font("Tahoma", 12 + y, System.Drawing.FontStyle.Italic); System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), wc, wc, 1.2F, true); g.DrawString(str_rnd_code.Substring(i, 1), font, brush, 4 + i * 11, 2 + random.Next(0, 6 - y)); } for (int i = 0; i <= 300; i++)//image noise { int x = random.Next(image.Width); int y = random.Next(image.Height); image.SetPixel(x, y, Color.FromArgb(random.Next())); } return image; } public bool IsReusable { get { return false; } } }