Create and verify the verification code when logging on to asp.net, and verify the asp.net verification code.

Create and verify the verification code when logging on to asp.net, and verify the asp.net verification code.

1. Create a page, ImageCode. aspx

2. Add the following code to Page_Load:

String tmp = RndNum (4 );
HttpCookie a = new HttpCookie ("ImageV", tmp );
Response. Cookies. Add ();
This. ValidateCode (tmp );

3. Add two methods to the 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 a random Generator

Random random = new Random ();

// Background color
G. Clear (Color. White );

For (int I = 0; I <100; 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 = ", 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 an image control on the page to display the verification code.

5. Add the following code on the front-end 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 one </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 verification code is correct:

String code = tbx_yzm.Text;
HttpCookie htco = Request. Cookies ["ImageV"];
String scode = htco. Value. ToString ();
If (code! = Scode)
{
Response. Write ("<script> alert ('incorrect verification code! ') </Script> ");
}

8. Results