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

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

<script type="text/javascript">
    function changeImg(obj) {
        obj.src="${pageContext.request.contextPath }/checkImg?time="+new Date().getTime();
    }
</script>

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>