一次性验证码

在jsp页面中 ,添加处理链接servlet的

<tr> <td style="text-align:right;width:20%;"> </td> <td colspan="2" style="width:50%"> <!--k1 图片由CheckImgServlet生成 --> <img src="${pageContext.request.contextPath}/servlet/CheckImgServlet" width="180" height="30" class="textinput" style="height:30px;" id="img" /> <!--k1 点一下文字链接切换验证图片 --> <a href="javascript:void(0);" onclick="changeImage()">看不清换一张</a> </td> </tr>

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前端JS脚本执行切换图片

<script type="text/javascript"> //前端点击切换图片,跳转到CheckImgServlet并把当前时间传过去 function changeImage() { document.getElementById("img").src ="${pageContext.request.contextPath}/servlet/CheckImgServlet?time="+ new Date().getTime(); } </script>

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验证码生成工具，将验证码文件new_words.txt放入/WEB-INF/目录下，随机读取保存到session中

public class CheckImgServlet extends HttpServlet { // 集合中保存所有成语 private List<String> words = new ArrayList<String>(); @Override public void init() throws ServletException { // web工程中读取 文件，必须使用绝对磁盘路径 String path = getServletContext().getRealPath("/WEB-INF/new_words.txt"); //创建一个使用默认大小输入缓冲区的BufferedReader BufferedReader reader = new BufferedReader(newInputStreamReader(new FileInputStream(path), "UTF-8")); String line; //读取一个文本行,如果已到达流末尾，则返回 null while ((line = reader.readLine()) != null) { //每一行放进集合 words.add(line); } reader.close(); } public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // 禁止缓存3种方式 // response.setHeader("Cache-Control", "no-cache"); // response.setHeader("Pragma", "no-cache"); response.setDateHeader("Expires", -1); int width = 120; int height = 30; // 步骤一 绘制一张内存中图片 BufferedImage bufferedImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); // 步骤二 图片绘制背景颜色 ---通过绘图对象 Graphics graphics = bufferedImage.getGraphics();// 得到画图对象 --- 画笔 // 绘制任何图形之前 都必须指定一个颜色 graphics.setColor(getRandColor(200, 250)); graphics.fillRect(0, 0, width, height); // 步骤三 绘制边框 graphics.setColor(Color.WHITE); graphics.drawRect(0, 0, width - 1, height - 1); // 步骤四 四个随机数字 Graphics2D graphics2d = (Graphics2D) graphics; // 设置输出字体 graphics2d.setFont(new Font("宋体", Font.BOLD, 18)); Random random = new Random();// 生成随机数 int index = random.nextInt(words.size()); String word = words.get(index);// 获得成语 System.out.println("session word=" + word); // 定义x坐标 int x = 10; for (int i = 0; i < word.length(); i++) { // 随机颜色 graphics2d.setColor(new Color(20 + random.nextInt(110), 20 + random .nextInt(110), 20 + random.nextInt(110))); // 旋转 -30 --- 30度 int jiaodu = random.nextInt(60) - 30; // 换算弧度 double theta = jiaodu * Math.PI / 180; // 获得字母数字 char c = word.charAt(i); // 将c 输出到图片 graphics2d.rotate(theta, x, 20); graphics2d.drawString(String.valueOf(c), x, 20); graphics2d.rotate(-theta, x, 20); x += 30; } //k4 将验证码内容保存session request.getSession().setAttribute("checkcode_session", word); // 步骤五 绘制干扰线 graphics.setColor(getRandColor(160, 200)); int x1; int x2; int y1; int y2; for (int i = 0; i < 30; i++) { x1 = random.nextInt(width); x2 = random.nextInt(12); y1 = random.nextInt(height); y2 = random.nextInt(12); graphics.drawLine(x1, y1, x1 + x2, x2 + y2); } // 将上面图片输出到浏览器 ImageIO graphics.dispose();// 释放资源 ImageIO.write(bufferedImage, "jpg", response.getOutputStream()); } private Color getRandColor(int fc, int bc) { // 取其随机颜色 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); } }

用户提交数据到servlet处理

public class UserRegisterServlet extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //用户输入的验证码 String ckcode = (String) request.getParameter("ckcode"); //session里面保存的验证码 String checkcode_session = (String) request.getSession().getAttribute("checkcode_session"); if (checkcode_session != null) { if (checkcode_session.equals(ckcode)) {//验证码符合条件 //用dbutils工具封装数据 Map<String, String[]> parameterMap = request.getParameterMap(); User user = new User(); BeanUtils.populate(user, parameterMap); System.out.println(user); // 插入用户数据,跳转到登陆成功界面 UserService service = new UserServiceImpl(); service.register(user); request.getRequestDispatcher("/registersuccess.jsp").forward(request, response); } else { //验证码不正确 request.setAttribute("ckcode_msg", "验证码有误!"); request.getRequestDispatcher("/register.jsp").forward(request,response); } } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }