ASP. NET -- production of the Verification Code, asp.net Verification Code

ASP. NET -- production of the Verification Code, asp.net Verification Code

We often encounter a verification code entry when logging on to the website, posting a blog or submitting a comment. At that time, we finally got in touch with niu Yi's news publishing system, here is a summary.

There are three things used: An aspx page and an image.

First, create An aspx page.

<% @ WebHandler Language = "C #" Class = "Picture" %> using System; using System. web; using System. drawing; using System. drawing. drawing2D; using System. web. sessionState; public class Picture: IHttpHandler, IRequiresSessionState // You must implement this interface to use session. Remember to import System. web. sessionState namespace {public void ProcessRequest (HttpContext context) {string checkCode = GenCode (5); // generates a five-character random context. session ["Code"] = checkCode; // Save the string to the Session so that System can be verified as needed. drawing. bitmap image = new System. drawing. bitmap (70, 22); Graphics g = Graphics. fromImage (image); try {// generate Random generator random Random = new Random (); // clear the image background color g. clear (Color. white); // specifies the background noise line of the image. int I; for (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. 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); // The foreground noise of the picture. 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); context. response. clearContent (); context. response. contentType = "image/Gif"; context. response. binaryWrite (ms. toArray ();} finally {g. dispose (); image. dispose ();}} /// <summary> /// generate a random string /// </summary> /// <param name = "num"> random output of several characters </param> // /<returns> random string </returns> private string GenCode (int num) {string str = "0123456789 ABCDEFGHIJKLMNOPQRSTUVWXYZ"; char [] chastr = str. toCharArray (); string code = ""; Random rd = new Random (); int I; for (I = 0; I <num; I ++) {// code + = source [rd. next (0, source. length)]; code + = str. substring (rd. next (0, str. length), 1) ;}return code ;}public bool IsReusable {get {return false ;}}}

Next, add an img control on the interface that uses the verification code, and the src property points to the. ashx file.

Then, determine whether the submitted verification code is correct.

// Determine whether the verification code is entered correctly string code = txtCode. text. trim (). toUpper (); // convert all input letters to uppercase and then compare them to string rightCode = Session ["Code"]. toString (); if (code! = RightCode) {Page. ClientScript. RegisterStartupScript (Page. GetType (), "message", "<script language = 'javascript 'defer> alert ('verification code input error! '); </Script> "); // The system prompts an error to ensure that the background remains unchanged. return ;}

Finally, use the commit crip to refresh the verification code. Because there are few codes, they can be nested in the code.

<Asp: Content ID = "Content1" ContentPlaceHolderID = "head" Runat = "Server"> <script language = "javascript" type = "text/javascript"> function changeCode () {var imgNode = document. getElementById ("vimg"); imgNode. src = "handler/WaterMark. ashx? T = "+ (new Date ()). valueOf (); // here, a time parameter is added to prevent browser cache problems.} </script> </asp: Content>

Create an ASPNET Verification Code

Display the verification code page (front-end)

<% @ Page Language = "C #" AutoEventWireup = "true" CodeFile = "AdminLogin. aspx. cs" Inherits = "Admin_AdminLogin" %>
<! DOCTYPE html PUBLIC "-// W3C // dtd xhtml 1.0 Transitional // EN" "www.w3.org/..al.dtd">
<Html xmlns = "www.w3.org/5o/xhtml">
<Head runat = "server">
<Title> Admin Logon </title>
<Script type = "text/javascript">
Function changeimg (){
Var myimg = document. getElementById ("img_Check ");
Now = new Date (); // if this event is not set, a bug can only be changed once.
Myimg. src = "AdminImage. aspx? Code = "+ now. getTime ();
}
</Script>
</Head>
<Body>
<Form id = "form1" runat = "server">
<Div align = "center">
<Table>
<Tr>
<Td align = "right">
Verification Code: <asp: TextBox ID = "tb_Check" runat = "server" Width = "70"> </asp: TextBox>
<Asp: Image ID = "img_Check" runat = "server" ImageUrl = "~ /Admin/AdminImage. aspx "Vis... the remaining full text>

How can I create an ASPNET verification code?

Webzixue.javaeye.com/blog/475841