HTML页面验证码生成方法（四位字幕）

/** * 验证码生成 * * @throws Exception */ public void validImage() throws Exception { response.setContentType("image/jpeg"); response.setHeader("Pragma", "No-cache"); response.setHeader("Cache-Control", "no-cache"); response.setDateHeader("Expires", 0); HttpSession session = request.getSession(); // 在内存中创建图象 int width = 60, height = 17; BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); // 获取图形上下文 Graphics g = image.getGraphics(); // 生成随机类 Random random = new Random(); // 设定背景色 int r1 = 200 + random.nextInt(250 - 200); int g1 = 200 + random.nextInt(250 - 200); int b1 = 200 + random.nextInt(250 - 200); g.setColor(new Color(r1, g1, b1)); g.fillRect(0, 0, width, height); // 设定字体 g.setFont(new Font("Times New Roman", Font.PLAIN, 18)); // 画边框 g.setColor(new Color(0, 0, 0)); g.drawRect(0, 0, width - 1, height - 1); // 随机产生155条干扰线，使图象中的认证码不易被其它程序探测到 int r2 = 160 + random.nextInt(200 - 160); int g2 = 160 + random.nextInt(200 - 160); int b2 = 160 + random.nextInt(200 - 160); g.setColor(new Color(r2, g2, b2)); 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); } // 取随机产生的认证码(4位数字) String sRand = ""; for (int i = 0; i < 4; i++) { String rand = String.valueOf(random.nextInt(10)); sRand += rand; // 将认证码显示到图象中 g.setColor(new Color(20 + random.nextInt(110), 20 + random .nextInt(110), 20 + random.nextInt(110)));// 调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成 g.drawString(rand, 13 * i + 6, 16); } // 将认证码存入SESSION session.setAttribute(SESSION_LOGIN_VALIDATION, sRand); // 图象生效 g.dispose(); ServletOutputStream responseOutputStream = response.getOutputStream(); // 输出图象到页面 ImageIO.write(image, "JPEG", responseOutputStream); // 以下关闭输入流！ responseOutputStream.flush(); responseOutputStream.close(); }