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Jsp login verification code

Source: Internet
Author: User
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Image. jsp

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<% @ Page language = "java" import = "java. awt. *, java. awt. image. *, java. util. *, javax. imageio. * "pageEncoding =" UTF-8 "%>
<%
String path = request. getContextPath ();
String basePath = request. getScheme () + ": //" + request. getServerName () + ":" + request. getServerPort () + path + "/";
%>

<! Doctype html public "-// W3C // dtd html 4.01 Transitional // EN">
<Html>
<Head>
<Base href = "<% = basePath %>">

<Title> My JSP 'images. jsp 'starting page </title>

<Meta http-equiv = "pragma" content = "no-cache">
<Meta http-equiv = "cache-control" content = "no-cache">
<Meta http-equiv = "expires" content = "0">
<Meta http-equiv = "keywords" content = "keyword1, keyword2, keyword3">
<Meta http-equiv = "description" content = "This is my page">
<! --
<Link rel = "stylesheet" type = "text/css" href = "styles.css">
-->

</Head>

<Body>
<%!
Color getRandColor (int fc, int bc) {// obtain a random Color from a given range
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 ();
// Set the page not to cache
Response. setheader ("Pragma", "No-Cache ");
Response. setheader ("cache-control", "No-Cache ");
Response. setdateheader ("expires", 0 );

// Create an image in memory
Int width = 60, Height = 20;
Bufferedimage image = new bufferedimage (width, height, bufferedimage. type_int_rgb );

// Obtain the image Context
Graphics G = image. getgraphics ();

// Generate a random class
Random random = new random ();

// Set the background color
G. setcolor (getrandcolor (200,250 ));
G. fillrect (0, 0, width, height );

// Set the font
G. setfont (new font ("Comic Sans MS", Font. Plain, 18 ));

// Generates 155 random interference lines, making the authentication code in the image hard to be detected by other programs.
G. setcolor (getrandcolor (220,240 ));
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 );
}

// Obtain the random ID code (4 digits)
String srand = "";
For (INT I = 0; I <4; I ++ ){
String Rand = string. valueof (random. nextint (10 ));
SRand + = rand;
// Display the authentication code to the image
G. setColor (new Color (20 + random. nextInt (110), 20 + random. nextInt (110), 20 + random. nextInt (110 )));
// The Color of the called function is the same. It may be because the seed is too close and can only be directly generated.
G. drawString (rand, 13 * I + 6, 16 );
}

// Save the authentication code to the SESSION
Session. setAttribute ("rand", sRand );

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

// Output the image to the page
ImageIO. write (image, "JPEG", response. getOutputStream ());
%>

 

</Body>
</Html>

 

-----------------------------

Code extracted from login. jsp

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Function loadimage (){
Document. getelementbyid ("randimage"). src = "images. jsp? "+ Math. Random ();
}

 

<Tr>
<TD width = "20%" Height = "15"> <Div align = "right"> <SPAN class = "style1"> Verification Code </span> </div> </ TD>
<TD width = "27%" Height = "15"> <Div align = "center">
& Nbsp; <input type = "text" name = "RAND" id = "RAND" style = "width: 55px; Height: 17px; Background-color: # ffffff; Border: solid 1px #7dbad7; font-size: 12px; color: # 2087bf "/>
</Div> </td>
<Td colspan = "2" width = "57%" height = "15"> & nbsp; </td>
</Tr>
<Tr>
<Td height = "10" colspan = "4" align = "center"> <a href = "javascript: loadimage (); "> <span class =" STYLE1 "> <font color =" red "> you cannot see it clearly. Change it to another one. </font> </span> </a> </td>
</Tr>

<C: if test = "$ {imageResult = 1}">
<Span class = "STYLE1"> <font color = "red"> the verification code is incorrect. Enter the verification code again. </Font> </span>
</C: if>

------------------------------------

KsuserAction. java

-----------------------------------

String rand = request. getParameter ("rand ");
String imageRand = (String) request. getSession (). getAttribute ("rand ");

If (rand. equals (imageRand )){
ImageResult =-1;
Return Default ();
} Else {
ImageResult = 1;
Return Login ();
}

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