Image Verification Code JSP

The image verification code used in the project some time ago. There are a lot of open-source image verification, written in jquery. But later I did not adopt it. I adopted the simplest one and shared it with you.

<% @ Page Language = "Java" contenttype = "image/JPEG" pageencoding = "UTF-8" %> <% @ page contenttype = "image/JPEG" Import = "Java. AWT. *, Java. AWT. image. *, Java. util. *, javax. imageIO. * "%> <% @ page import =" Java. io. outputstream "%> <%! Color getrandcolor (int fc, int BC) {// obtain the random color 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) ;}%> <% Try {// set the page to not cache response. setheader ("Pragma", "No-Cache"); response. setheader ("cache-control", "No-Cache"); response. setdateheader ("expires", 0); // create an image in the memory int width = 60, Height = 20; bufferedimage image = new bufferedimage (width, height, bufferedimage. type_int_rgb); outputstream OS = response. getoutputstream (); // obtain the image context graphics G = image. getgraphics (); // generate random class 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 ("Times New Roman", Font. plain, 18); // draw a border // G. setcolor (new color (); // G. drawrect (155, width-1, height-1); // generates random interference lines, making the identification code in the image hard to be detected by other programs. 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);} // obtain the random ID code (4 digits) string srand = ""; for (INT I = 0; I <4; I ++) {// string Rand = string. valueof (random. nextint (10); // number // string Rand = string. valueof (char) (math. round (math. random () * 25 + 65); // uppercase http://www.itstudy.cn/string Rand = string. valueof (char) (math. round (math. random () * 25 + 97); // lowercase srand + = rand; // display the ID code to the image G. setcolor (new color (20 + random. nextint (110), 20 + random. nextint (110), 20 + random. nextint (110); // The color from the call function is the same, probably because the seed is too close, so you can only generate G directly. drawstring (RAND, 13 * I + 6, 16);} // Save the authentication code to the session. setattribute ("RAND", srand); // image effective G. dispose (); // output the image to the ImageIO page. write (image, "Jpeg", OS); OS. flush (); OS. close (); OS = NULL; response. flushbuffer (); out. clear (); out = pagecontext. pushbody ();} catch (illegalstateexception e) {system. out. println (E. getmessage (); E. printstacktrace () ;}%>