Asp.net(C#)实现验证码功能

ASP.net 验证码(C#)
/* 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());
  }


 
Web 窗体设计器生成的代码

 
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();
   }

  }

}



 

  假如以上验证码生成器页面名为:CheckCode.aspx,那么在登录页面中使用“
<IMG>” 这个 HTML 元素来显示生成的验证码图片:<IMG src="CheckCode.aspx">
  在登录页面的登录按钮的处理事件中使用以下代码判断验证码:


 
private void btnLogin_Click(object sender, System.Web.UI.ImageClickEventArgs e)
 
{
  
if(Request.Cookies["CheckCode"] == null)
  
{
    lblMessage.Text
= "您的浏览器设置已被禁用 Cookies,您必须设置浏览器允许使用 Cookies 选项后才能使用本系统。";
    lblMessage.Visible
= true;
   
return;
   }


  
if(String.Compare(Request.Cookies["CheckCode"].Value, txtCheckCode.Text, true) != 0)
  
{
    lblMessage.Text
= "验证码错误,请输入正确的验证码。";
    lblMessage.Visible
= true;
   
return;
   }


       
/*****  其他代码  *****/

  }

posted on 2007-05-28 09:36  书生  阅读(326)  评论(0编辑  收藏  举报

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