public static String getCaptcha(HttpServletRequest request, HttpServletResponse response) { try { final String captchaSizeConfigName = StringUtils.defaultIfEmpty(request.getParameter("captchaSize"), "default"); final String captchaSizeConfig = UtilProperties.getPropertyValue("captcha.properties", "captcha." + captchaSizeConfigName); final String[] captchaSizeConfigs = captchaSizeConfig.split("\\|"); final String captchaCodeId = StringUtils.defaultIfEmpty( request.getParameter("captchaCodeId"), ""); // this is used to uniquely identify in the user session the attribute where the // captcha code for the last captcha for the form is stored final int fontSize = Integer.parseInt(captchaSizeConfigs[0]); final int height = Integer.parseInt(captchaSizeConfigs[1]); final int width = Integer.parseInt(captchaSizeConfigs[2]); final int charsToPrint = UtilProperties.getPropertyAsInteger("captcha.properties", "captcha.code_length", 6); final char[] availableChars = UtilProperties.getPropertyValue("captcha.properties", "captcha.characters").toCharArray(); // It is possible to pass the font size, image width and height with the request as well Color backgroundColor = Color.gray; Color borderColor = Color.DARK_GRAY; Color textColor = Color.ORANGE; Color circleColor = new Color(160, 160, 160); Font textFont = new Font("Arial", Font.PLAIN, fontSize); int circlesToDraw = 6; float horizMargin = 20.0f; double rotationRange = 0.7; // in radians BufferedImage bufferedImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); Graphics2D g = (Graphics2D) bufferedImage.getGraphics(); g.setColor(backgroundColor); g.fillRect(0, 0, width, height); // Generating some circles for background noise g.setColor(circleColor); for (int i = 0; i < circlesToDraw; i++) { int circleRadius = (int) (Math.random() * height / 2.0); int circleX = (int) (Math.random() * width - circleRadius); int circleY = (int) (Math.random() * height - circleRadius); g.drawOval(circleX, circleY, circleRadius * 2, circleRadius * 2); } g.setColor(textColor); g.setFont(textFont); FontMetrics fontMetrics = g.getFontMetrics(); int maxAdvance = fontMetrics.getMaxAdvance(); int fontHeight = fontMetrics.getHeight(); String captchaCode = RandomStringUtils.random(6, availableChars); float spaceForLetters = -horizMargin * 2 + width; float spacePerChar = spaceForLetters / (charsToPrint - 1.0f); for (int i = 0; i < captchaCode.length(); i++) { // this is a separate canvas used for the character so that // we can rotate it independently int charWidth = fontMetrics.charWidth(captchaCode.charAt(i)); int charDim = Math.max(maxAdvance, fontHeight); int halfCharDim = (charDim / 2); BufferedImage charImage = new BufferedImage(charDim, charDim, BufferedImage.TYPE_INT_ARGB); Graphics2D charGraphics = charImage.createGraphics(); charGraphics.translate(halfCharDim, halfCharDim); double angle = (Math.random() - 0.5) * rotationRange; charGraphics.transform(AffineTransform.getRotateInstance(angle)); charGraphics.translate(-halfCharDim, -halfCharDim); charGraphics.setColor(textColor); charGraphics.setFont(textFont); int charX = (int) (0.5 * charDim - 0.5 * charWidth); charGraphics.drawString( "" + captchaCode.charAt(i), charX, ((charDim - fontMetrics.getAscent()) / 2 + fontMetrics.getAscent())); float x = horizMargin + spacePerChar * (i) - charDim / 2.0f; int y = ((height - charDim) / 2); g.drawImage(charImage, (int) x, y, charDim, charDim, null, null); charGraphics.dispose(); } // Drawing the image border g.setColor(borderColor); g.drawRect(0, 0, width - 1, height - 1); g.dispose(); response.setContentType("image/jpeg"); ImageIO.write(bufferedImage, "jpg", response.getOutputStream()); HttpSession session = request.getSession(); Map captchaCodeMap = (Map) session.getAttribute("_CAPTCHA_CODE_"); if (captchaCodeMap == null) { captchaCodeMap = new HashMap(); session.setAttribute("_CAPTCHA_CODE_", captchaCodeMap); } captchaCodeMap.put(captchaCodeId, captchaCode); } catch (Exception ioe) { Debug.logError(ioe.getMessage(), module); } return "success"; }