Production and verification of verification code in ASP.

1. Create a new page, imagecode.aspx

2. Add the following code to the Page_Load

string tmp = Rndnum (4);
HttpCookie a = new HttpCookie ("Imagev", TMP);
Response.Cookies.Add (a);
This. Validatecode (TMP);

3. Add two methods to this page

private void Validatecode (String vnum)
{

Bitmap Img = null;

Graphics g = null;

MemoryStream ms = NULL;

int gheight = vnum.length * 12;

IMG = new Bitmap (gheight, 25);

g = Graphics.fromimage (IMG);

Generate Random Generators

Random random = new random ();

Background color
G.clear (Color.White);

for (int i = 0; i <; i++)
{

int x = random. Next (Img.width);

int y = random. Next (Img.height);

Img.setpixel (x, Y, Color.FromArgb (random. Next ()));

}

Text font
Font f = new Font ("Arial Black", 12);

Text color
SolidBrush s = new SolidBrush (Color.Blue);

g.DrawString (Vnum, F, S, 3, 3);

ms = new MemoryStream ();

Img.save (MS, Imageformat.jpeg);

Response.clearcontent ();

Response.ContentType = "Image/jpeg";

Response.BinaryWrite (Ms. ToArray ());

G.dispose ();
Img.dispose ();
Response.End ();

}

private string rndnum (int vcodenum)
{

String Vchar = "0,1,2,3,4,5,6,7,8,9,a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p" +

", q,r,s,t,u,v,w,x,y,z";

string[] Vcarray = Vchar.split (new char[] {', '});

String vnum = "";
int temp =-1;
Random rand = new Random ();

for (int i = 1; i < Vcodenum + 1; i++)
{
if (temp! =-1)
{
Rand = new Random (i * temp * unchecked ((int) DateTime.Now.Ticks));

}
int t = rand. Next (35);
if (temp! =-1 && temp = = t)
{
Return Rndnum (Vcodenum);

}
temp = t;
Vnum + = vcarray[t];

}

return vnum;

}

4. Add a picture control on the page that needs to display the verification code

5. Add the following code to the front page of the page:

Verification Code:
<asp:textbox id= "Tbx_yzm" runat= "Server" width= "70px" ></asp:TextBox>
<asp:imagebutton id= "Ibtn_yzm" runat= "Server"/>
<a href= "Javascript:changecode ()" style= "text-decoration:underline; font-size:10px; " > Change a new </a>
<script type= "Text/javascript" >
function ChangeCode ()
{
document.getElementById (' Ibtn_yzm '). src = document.getElementById (' ibtn_yzm '). src + '? ';
}
</script>

6. Add the following code to the Page_Load event on this page:

Ibtn_yzm. IMAGEURL = "imagecode.aspx";

7. Verify that the code is entered correctly:

String code = Tbx_yzm. Text;
HttpCookie Htco = request.cookies["Imagev"];
String scode = Htco. Value.tostring ();
if (Code! = SCODE)
{
Response.Write ("<script>alert (' CAPTCHA input is incorrect! ') </script> ");
}

8. Effects

Production and verification of verification code in ASP.