ASP.net 驗證碼(C#)

2024-07-10 13:07:21

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public class validatecode : system.web.ui.page
   {
   private void page_load(object sender, system.eventargs e)
   {
   this.createcheckcodeimage(generatecheckcode());
   }

   #region web 窗體設計器生成的代碼
   override protected void oninit(eventargs e)
   {
   //
   // codegen: 該調用是 asp.net web 窗體設計器所必需的。
   //
   initializecomponent();
   base.oninit(e);
   }

   /// <summary>
   /// 設計器支持所需的方法 - 不要使用代碼編輯器修改
   /// 此方法的內容。
   /// </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
   {
   //生成隨機生成器
   random random = new random();

   //清空圖片背景色
   g.clear(color.white);

   //畫圖片的背景噪音線
   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);

   //畫圖片的前景噪音點
   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()));
   }

   //畫圖片的邊框線
   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();
   }
   }
   }

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