How to make website CAPTCHA
This article introduces you how to make the verification code of the website, the content is very detailed, interested friends can refer to, I hope it can be helpful to you.
Production of asp.net CAPTCHA
Using System
Using System.IO
Using System.Drawing
Using System.Drawing.Imaging
Using System.Text
Using System.Collections
Using System.Web
Using System.Web.UI
Using System.Web.UI.WebControls
Using System.Web.UI.WebControls.WebParts
Using System.Web.UI.HtmlControls
Namespace WebApplication1
{
Public partial class yzm: System.Web.UI.Page
{
Protected void Page_Load (object sender, EventArgs e)
{
String chkCode = string.Empty
/ / Color list, which is used for verification code, noise line, noise point
Color [] color = {Color.Black, Color.Red, Color.Blue, Color.Green, Color.Orange, Color.Brown, Color.Brown, Color.DarkBlue}
/ / Font list, used for CAPTCHA
String [] font = {"Times New Roman", "MS Mincho", "Book Antiqua", "Gungsuh", "PMingLiU", "Impact"}
/ / the character set of the CAPTCHA, removing some characters that are easy to be confused
Char [] character = {'2, 3, 4, 5, 6, 8, 9, A, B, C, D, E, F, G, H, J, K, L, M, N, P, R, S, T, W' 'Xuan,'Y'}
Random rnd = new Random ()
/ / generate a CAPTCHA string
For (int I = 0; I < 4; iTunes +)
{
ChkCode + = "[rnd.Next (character.Length)]
}
/ / use session object to store CAPTCHA
Session ["name"] = chkCode
Bitmap bmp = new Bitmap (100,40)
Graphics g = Graphics.FromImage (bmp)
G.Clear (Color.White)
/ / draw noise lines
For (int I = 0; I < 10; iTunes +)
{
Int x1 = rnd.Next (100)
Int Y1 = rnd.Next (40)
Int x2 = rnd.Next (100)
Int Y2 = rnd.Next (40)
Color clr = color [rnd.Next (color.Length)]
G.DrawLine (new Pen (clr), x1, y1, x2, y2)
}
/ / draw CAPTCHA string
For (int I = 0; I < chkCode.Length; iTunes +)
{
String fnt = Font [rnd.Next (font.Length)]
Font ft = new Font (fnt, 18)
Color clr = color [rnd.Next (color.Length)]
G.DrawString (chkCode [I] .ToString (), ft, new SolidBrush (clr), (float) I * 20 + 8, (float) 8)
}
/ / draw noise
For (int I = 0; I < 100; iTunes +)
{
Int x = rnd.Next (bmp.Width)
Int y = rnd.Next (bmp.Height)
Color clr = color [rnd.Next (color.Length)]
Bmp.SetPixel (x, y, clr)
}
/ / clear the page output cache and set the page to have no cache
Response.Buffer = true
Response.ExpiresAbsolute = System.DateTime.Now.AddMilliseconds (0)
Response.Expires = 0
Response.CacheControl = "no-cache"
Response.AppendHeader ("Pragma", "No-Cache")
/ / write the CAPTCHA image to the memory stream and output it in "p_w_picpath/Png" format
MemoryStream ms = new MemoryStream ()
Try
{
Bmp.Save (ms, ImageFormat.Png)
Response.ClearContent ()
Response.ContentType = "p_w_picpath/Png"
Response.BinaryWrite (ms.ToArray ())
}
Finally
{
/ / explicitly release resources
Bmp.Dispose ()
G.Dispose ()
}
}
}
}
About how to carry on the website CAPTCHA production to share here, hope that the above content can have some help to everyone, can learn more knowledge. If you think the article is good, you can share it for more people to see.
