Generate images with 4 random numbers and messy backgrounds, the numbers and background colors will change, the server is new (use history.go (-1) variable) prototype reference Alibaba
http://china.alibaba.com/member/showimage
------------ Generate a verification code picture ----- image.jsp ------------------------ ------------------- <% @ Page ContentType = "image / jpeg" import = "java.awt. *, Java.awt.image. *, Java.util * "%> <%! Color getrandcolor (int FC, int bc) {// given random color 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);}%> <% // Settings page does not cache Response.setHeader ("Pragma", "NO-Cache"); response.setheader ("cache-control", " "); response.setdateHeader (" expires ", 0); // Create image in memory int width = 60, Height = 20; bufferedimage image = new bufferedImage (width, height, bufferedimage.type_int_rgb); / / Get graphics context graphics g = image.getgraphics (); // Generate random class random random = new random (); // Set background color G.SetColor (GetrandColor (200, 25)); g.FillRect (0, 0, Width, height); // Set font G.SetFont (New Font ("Times New Roman", Font.Plain, 18)); // Section Box //g.SetColor (New Color ()); //g .drawRect (0, 0, Width-1, H EIGHT-1); // randomly generate 155 interferent lines, enabling the authentication code in the image to detect 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);} // Take the randomly generated authentication code (4 digits) 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 call is the same, it may be because the seed is too close, so only directly generate G.DrawString (Rand, 13 * i 6, 16);} // Deposit the authentication code in sessionSession.setttribute ("Rand) ", SRAND); // Image Effective g.dispose (); // Output Image to Page Imageio.write (Image," JPEG ", Response.getOutputStream ());%> -------- ------- Use the verification code picture --------- A.jsp ------------------------- ----------- <% @ Page ContentType = "Text / HTML; Charset = GB2312"%> < HTML>
authentication code input page </ title> <meta http-equiv = "content-type" content = "text / html; charSet = GB2312"> <meta http-equiv = "pragma" content = "no-cache"> <meta http-equiv = "cache-control" content = "no-cache"> <meta http-equiv = "expires" content = "0"> </ head> <body> <form method = post action = "check.jsp"> <table> <tr> <td align = LEFT> The authentication code generated by the system: </ td> <TD> <img border = 0 src = "image.jsp"> </ TD> </ tr> <tr> <TD align = left> Enter the above authentication code: </ td> <TD> <input type = text name = rand maxlength = 4 value = "> </ td> </ Tr> <Tr> <TD COLSPAN = 2 Align = Center> <input type = submit value = "Submit Detection"> </ TD> </ TR> </ form> </ body> </ html> ---- ------------- Verified page ---------- Check.jsp.jsp <% @ Page ContentType = "Text / HTML; Charset = GB2312" Language = "Java" Import = "java.sql. *" ErrorPage = ""%> <HTML> <head> <title> authentication code verification page </ Title> <meta http-equiv = "content-type"</p></div><div class="text-center mt-3 text-grey">
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</ul></div></div><div class="d-none threadlist"><input type="checkbox" name="modtid" value="33711" checked /></div></div></div></div></div><footer class="text-muted small bg-dark py-4 mt-3" id="footer"><div class="container"><div class="row"><div class="col">CopyRight © 2020 All Rights Reserved
</div><div class="col text-right">Processed:
<b>0.052</b>, SQL:
<b>9</b></div></div></div></footer><script src="./lang/en-us/lang.js?2.2.0"></script><script src="view/js/jquery.min.js?2.2.0"></script><script src="view/js/popper.min.js?2.2.0"></script><script src="view/js/bootstrap.min.js?2.2.0"></script><script src="view/js/xiuno.js?2.2.0"></script><script src="view/js/bootstrap-plugin.js?2.2.0"></script><script src="view/js/async.min.js?2.2.0"></script><script src="view/js/form.js?2.2.0"></script><script>
var debug = DEBUG = 0;
var url_rewrite_on = 1;
var url_path = './';
var forumarr = {"1":"Tech"};
var fid = 1;
var uid = 0;
var gid = 0;
xn.options.water_image_url = 'view/img/water-small.png';
</script><script src="view/js/wellcms.js?2.2.0"></script><a class="scroll-to-top rounded" href="javascript:void(0);"><i class="icon-angle-up"></i></a><a class="scroll-to-bottom rounded" href="javascript:void(0);" style="display: inline;"><i class="icon-angle-down"></i></a></body></html><script>
var forum_url = 'list-1.html';
var safe_token = 'b0zKi6N03aboV_2FuspPhsZUUkD6_2Btc63Rb_2FwBe8IwkczH_2FvIxF1PX6LVJ4fc7qu28yV0QwNrqiozR2NnsDmBx3A_3D_3D';
var body = $('body');
body.on('submit', '#form', function() {
var jthis = $(this);
var jsubmit = jthis.find('#submit');
jthis.reset();
jsubmit.button('loading');
var postdata = jthis.serializeObject();
$.xpost(jthis.attr('action'), postdata, function(code, message) {
if(code == 0) {
location.reload();
} else {
$.alert(message);
jsubmit.button('reset');
}
});
return false;
});
function resize_image() {
var jmessagelist = $('div.message');
var first_width = jmessagelist.width();
jmessagelist.each(function() {
var jdiv = $(this);
var maxwidth = jdiv.attr('isfirst') ? first_width : jdiv.width();
var jmessage_width = Math.min(jdiv.width(), maxwidth);
jdiv.find('img, embed, iframe, video').each(function() {
var jimg = $(this);
var img_width = this.org_width;
var img_height = this.org_height;
if(!img_width) {
var img_width = jimg.attr('width');
var img_height = jimg.attr('height');
this.org_width = img_width;
this.org_height = img_height;
}
if(img_width > jmessage_width) {
if(this.tagName == 'IMG') {
jimg.width(jmessage_width);
jimg.css('height', 'auto');
jimg.css('cursor', 'pointer');
jimg.on('click', function() {
});
} else {
jimg.width(jmessage_width);
var height = (img_height / img_width) * jimg.width();
jimg.height(height);
}
}
});
});
}
function resize_table() {
$('div.message').each(function() {
var jdiv = $(this);
jdiv.find('table').addClass('table').wrap('<div class="table-responsive"></div>');
});
}
$(function() {
resize_image();
resize_table();
$(window).on('resize', resize_image);
});
var jmessage = $('#message');
jmessage.on('focus', function() {if(jmessage.t) { clearTimeout(jmessage.t); jmessage.t = null; } jmessage.css('height', '6rem'); });
jmessage.on('blur', function() {jmessage.t = setTimeout(function() { jmessage.css('height', '2.5rem');}, 1000); });
$('#nav li[data-active="fid-1"]').addClass('active');
</script>
