IGeekShop案例9 -实现验证码功能

ゝ一纸荒年。 2024-04-17 14:10 10阅读 0赞

# IGeekShop案例9 -实现验证码功能 #

## 1 改写jsp代码 ##

![在这里插入图片描述][20190827105915862.png]

## 2 编写自动生成验证码的servlet ##

直接使用模板  
动态生成验证码Servlet代码模板

package checking;
    
    import java.awt.Color;
    import java.awt.Font;
    import java.awt.Graphics;
    import java.awt.Graphics2D;
    import java.awt.image.BufferedImage;
    import java.io.BufferedReader;
    import java.io.FileReader;
    import java.io.IOException;
    import java.util.ArrayList;
    import java.util.List;
    import java.util.Random;
    
    import javax.imageio.ImageIO;
    import javax.servlet.ServletException;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    /**
     * 验证码生成程序
     */
    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 {
            // 初始化阶段，读取new_words.txt
            // 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");
            try {
                BufferedReader reader = new BufferedReader(new FileReader(path));
                String line;
                while ((line = reader.readLine()) != null) {
                    words.add(line);
                }
                reader.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    
        public void doGet(HttpServletRequest request, HttpServletResponse response)
                throws ServletException, IOException {
            // 禁止缓存
            // 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
    
            // 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;
            }
            // 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
            
            //将图片写到response.getOutputStream()中
            ImageIO.write(bufferedImage, "jpg", response.getOutputStream());
    
        }
    
        public void doPost(HttpServletRequest request, HttpServletResponse response)
                throws ServletException, IOException {
            doGet(request, response);
        }
    
        /**
         * 取其某一范围的color
         * 
         * @param fc
         *            int 范围参数1
         * @param bc
         *            int 范围参数2
         * @return Color
         */
        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);
        }
    
    }

## 3 实现点击动态改变 ##

![在这里插入图片描述][20190827110042401.png]

## 4 实现验证码的校验功能 ##

package www.test.web.servlet;
    
    import java.io.IOException;
    import java.sql.SQLException;
    
    import javax.servlet.ServletException;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    import www.test.domain.User;
    import www.test.service.LoginService;
    
    public class LoginServlet extends HttpServlet {
    
        public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    
            // 解决乱码问题
            request.setCharacterEncoding("UTF-8");
    
            // 获得页面输入的验证
            String checkCode_client = request.getParameter("checkCode");
            // 获得生成图片的文字的验证码
            String checkCode_session = (String) request.getSession().getAttribute("checkcode_session");
            // 比对页面的和生成图片的文字的验证码是否一致
            if (!checkCode_session.equals(checkCode_client)) {
                request.setAttribute("loginInfo", "您的验证码不正确");
                request.getRequestDispatcher("/login.jsp").forward(request, response);
                return; //验证码输入错误的话，就没有必要获取输入的用户名和密码
            }
            // 获取用户输入的数据  
            String username = request.getParameter("username");
            String password = request.getParameter("password");
    
            LoginService service = new LoginService();
            User user = null;
            try {
                user = service.findUser(username, password);
            } catch (SQLException e) {
    
                e.printStackTrace();
            }
    
            if (user != null) {
                response.sendRedirect("/WEBTest24/index.jsp");
            } else {
                request.getRequestDispatcher("/login.jsp").forward(request, response);
                ;
            }
        }
    
        public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            doGet(request, response);
        }
    
    }

<div id="checkCodeInfo" style="color:red">${loginInfo}</div>

[20190827105915862.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/17/8cf49893b98e418490bb6304e6066432.png
[20190827110042401.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/17/1b131b6a483444a9a4e3b2c78225a9b5.png