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How to generate a page verification code using Jsp [Code]

Source: Internet
Author: User
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Image. jsp -------------------------------- Jsp page for Generating Random verification code Images
The Code is as follows: Copy codeThe Code is as follows: <% @ page contentType = "image/jpeg" import = "java. awt .*,
Java. awt. image. *, java. util. *, javax. imageio. * "%>
<%!
Color getRandColor (int fc, int bc)
{
Random random = new Random ();
If (fc> 255) fc = 255;
If (bc> 255) bc = 255;
Int r = fc + random. nextInt (bc-fc );
Int g = fc + random. nextInt (bc-fc );
Int B = fc + random. nextInt (bc-fc );
Return new Color (r, g, B );
}
%>
<%
Out. clear (); // This sentence is for the resin server. If it is tomacat, do not use this sentence.
Response. setHeader ("Pragma", "No-cache ");
Response. setHeader ("Cache-Control", "no-cache ");
Response. setDateHeader ("Expires", 0 );
Int width = 60, height = 20;
BufferedImage image = new BufferedImage (width, height, BufferedImage. TYPE_INT_RGB );
Graphics g = image. getGraphics ();
Random random = new Random ();
G. setColor (getRandColor (200,250 ));
G. fillRect (0, 0, width, height );
G. setFont (new Font ("Times New Roman", Font. PLAIN, 18 ));
G. setColor (getRandColor (160,200 ));
For (int I = 0; I <155; I ++)
{
Int x = random. nextInt (width );
Int y = random. nextInt (height );
Int xl = random. nextInt (12 );
Int yl = random. nextInt (12 );
G. drawLine (x, y, x + xl, y + yl );
}
String sRand = "";
For (int I = 0; I <4; I ++ ){
String rand = String. valueOf (random. nextInt (10 ));
SRand + = rand;
G. setColor (new Color (20 + random. nextInt (110), 20 + random. nextInt (110), 20 + random. nextInt (110 )));
G. drawString (rand, 13 * I + 6, 16 );
}
// Save the authentication code to the SESSION
Session. setAttribute ("rand", sRand );
G. dispose ();
ImageIO. write (image, "JPEG", response. getOutputStream ());
%>

Logic. jsp ---------------------------------- on the login page, enter the verification code here and submit and verify
The Code is as follows:Copy codeThe Code is as follows: <% @ page contentType = "text/html; charset = gbk" %>
<% @ Page language = "java" import = "java. SQL. *" errorPage = "" %>
<Html>
<Head>
<Meta http-equiv = "Content-Type" content = "text/html; charset = gb2312">
<Title> User Logon </title>
<Script language = "javascript">
Function loadimage (){
Document. getElementById ("randImage"). src = "image. jsp? "+ Math. random ();
}
</Script>
</Head>
<Body>
<Table width = "256" border = "0" cellpadding = "0" cellspacing = "0">
<! -- DWLayoutTable -->
<Form action = "validate. jsp" method = "post" name = "loginForm">
<Tr>
<Td width = "118" height = "22" valign = "middle" align = "center"> <input type = "text" name = "rand" size = "15"> </td>
<Td width = "138" valign = "middle" align = "center"> </td>
</Tr>
<Tr>
<Td height = "36" colspan = "2" align = "center" valign = "middle"> <a href = "javascript: loadimage (); "> <font class = pt95> cannot see me </font> </a> </td>
</Tr>
<Tr>
<Td height = "36" colspan = "2" align = "center" valign = "middle"> <input type = "submit" name = "login" value = "submit"> </td>
</Tr>
</Form>
</Table>
</Body>
</Html>

Validate. jsp -------------------------- used to verify that the entered verification code is correct
The Code is as follows:Copy codeThe Code is as follows: <% @ page contentType = "text/html; charset = gb2312" language = "java" import = "java. SQL. *" errorPage = "" %>
<%
String rand = (String) session. getAttribute ("rand ");
String input = request. getParameter ("rand ");
If (rand. equals (input )){
Out. print ("<script> alert ('verification passed! '); </Script> ");
} Else {
Out. print ("<script> alert ('Enter the correct verification code! '); Location. href = 'login. jsp'; </script> ");
}
%>

The above three JSP pages are placed in the directory of the same level as the WEB-INF, if you put in a different folder, then the path of the relevant page inside yourself for a slight change on it.
Tip: Exceptions may occur in Tomcat 5 or earlier versions.

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Related Keywords:
how to generate random code in php how to generate html page dynamically using php convert php to jsp code online jsp sample code how to make website using html code how to send email using php code how to code website using html
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