An example class that generates a verification code using Java code

Call in JSP as follows:

<Table width = "100%" border = "0" cellpadding = "0" cellspacing = "0" style = "margin: 0 auto;">
<Tr>
<TD width = "20"> <HTML: Text property = "validatecode" size = "8"/> </TD>

<TD> & nbsp; </TD> <TD align = "Left" valign = "TOP"> <Div id = "validatecodeimage" valign = "TOP"> </div>

<SCRIPT type = "text/JavaScript"> updatevalidatecode (70, 25) </SCRIPT> <

/TD>
</Tr>
</Table>

JS scripts

Function updatevalidatecode (width, height ){
Document. getelementbyid ('validatecodeimag '). innerhtml = '/validatecode. do "style =" cursor: Hand "alt =" if you cannot see the verification code, please click picture refresh "/> ';
}

Import java. AWT. color;
Import java. AWT. Font;
Import java. AWT. graphics;
Import java. AWT. image. bufferedimage;
Import java. Io. ioexception;
Import java. util. Random;

Import javax. ImageIO. ImageIO;
Import javax. servlet. http. httpservletrequest;
Import javax. servlet. http. httpservletresponse;

Import org. Apache. commons. Lang. stringutils;
Import org. Apache. Struts. action. Action;
Import org. Apache. Struts. Action. actionform;
Import org. Apache. Struts. Action. actionforward;
Import org. Apache. Struts. Action. actionmapping;

/**
* Myeclipse struts creation date: 05-31-2007
*
* XDoclet definition:
*
* @ Struts. Action validate = "true"
*/
Public class validatecodeaction extends action {
/*
* Generated Methods
*/

/**
* Method Execute
*
* @ Param Mapping
* @ Param form
* @ Param request
* @ Param response
* @ Return actionforward
*/
Public actionforward execute (actionmapping mapping, actionform form,
Httpservletrequest request, httpservletresponse response ){
// Set the length and width of the image
Int width = stringutils. isnotblank (request. getparameter ("width "))? Integer
. Parseint (request. getparameter ("width "))
: 0;
Int Height = stringutils. isnotblank (request. getparameter ("height "))? Integer
. Parseint (request. getparameter ("height "))
: 0;
If (width <70 | width> 140 ){
Width = 70;
}
If (height <25 | height> 50 ){
Height = 25;
}

// Create memory image
Bufferedimage image = new bufferedimage (width, height,
Bufferedimage. type_int_rgb );
// Obtain the image Context
Graphics G = image. creategraphics ();

// Set the background color of the image (because it is a background, so it is light)
G. setcolor (getrandcolor (180,250 ));
G. fillrect (0, 0, width, height );
// Set the font
G. setfont (new font ("Arial", Font. Bold, 19 ));

// Four verification codes are generated by default.
Int length = 4;
// Set Random Seed
Java. util. Random Rand = new random ();

// Set the alternative verification code, which includes "a-Z" and numbers "0-9". Some confusing characters are removed.
String base = "abcdefghijkmnqrstuvwxyz23456789 ";
Int size = base. Length ();
Stringbuffer STR = new stringbuffer ();
For (INT I = 0; I <length; I ++ ){
Int start = Rand. nextint (size );
String tmpstr = base. substring (start, start + 1 );

Str. append (tmpstr );
// Generate a random color (because it is a foreground, so it is too deep)
G. setcolor (getrandcolor (10,150 ));

// Draw the word on the Image
// G. drawstring (Str. tostring (), 4, 17 );
G. drawstring (tmpstr, 13 * I + 6 + Rand. nextint (5), 14 + Rand
. Nextint (6 ));
// Random image points
For (Int J = 0; j <20; j ++ ){
Int x = Rand. nextint (width );
Int y = Rand. nextint (height );
G. drawoval (X, Y, 0, 0 );
}
/*
// Draw a random line
For (Int J = 0; j <2; j ++ ){
Int x = Rand. nextint (width );
Int y = Rand. nextint (height );
Int X1 = Rand. nextint (12 );
Int Y1 = Rand. nextint (12 );
G. drawline (X, Y, x + X1, Y + Y1 );
}
*/
}

// Save the authentication code to the session
Request. getsession (). setattribute ("validatecode", str. tostring ());

// The image takes effect
G. Dispose ();

// Set the page not to cache
Response. setdateheader ("expires",-1 );
Response. setheader ("cache-control ",
"No-store, Private, post-check = 0, pre-check = 0, Max-age = 0 ");
Response. setheader ("Pragma", "No-Cache ");

// Output the image to the page
Try {
ImageIO. Write (image, "Jpeg", response. getoutputstream ());
} Catch (ioexception e ){
E. printstacktrace ();
}

Return NULL;
}

// Obtain a random color in a given range
Color getrandcolor (int fc, int BC ){
Random random = new random ();
'If (FC> 255 ){
Fc = 255;
}
If (BC & gt; 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 );
}

}