使用java编写验证码

素颜马尾好姑娘i 2022-12-05 10:29 148阅读 0赞

package com.servlet;
    
    import javax.imageio.ImageIO;
    import javax.servlet.ServletException;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import java.awt.*;
    import java.awt.image.BufferedImage;
    import java.io.IOException;
    import java.util.Random;
    
    /** * 验证码 * 猜想：生成的验证码，到时候可以跟输入的账号一起存到缓存redis中，key工号 value验证码 设置过期时间 * 用户输入验证码点击确定之后，获取redis中的数据进行比对，如果获取不到缓存说明已经过期，页面刷新，重新插入一条验证码到缓存中。 * 进行验证正确就允许登陆 */
    public class ImageServlet extends HttpServlet { 
        @Override
        protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { 
            //如何让浏览器3秒自动刷新一次;
            resp.setHeader("refresh","3");
            BufferedImage bufferedImage = new BufferedImage(90,30,BufferedImage.TYPE_INT_RGB);
            Graphics2D graphics = (Graphics2D)bufferedImage.getGraphics();
            //填充颜色
            graphics.setColor(Color.BLUE);
            //画一个边框
            graphics.fillRect(0,0,90,30);
            //给图片写数据
            graphics.setColor(Color.yellow);
            graphics.setFont(new Font(null,Font.BOLD,20));
            graphics.drawString(getRandomNum(),10,20);
    
            //告诉浏览器，这个请求用图片的方式打开
            resp.setContentType("image/jpeg");
            //网站存在缓存，不让浏览器缓存
            resp.setDateHeader("expires",-1);
            resp.setHeader("Cache-Control","no-cache");
            resp.setHeader("Pragma","no-cache");
            //把图片写给浏览器
            ImageIO.write(bufferedImage,"jpg",resp.getOutputStream());
    
        }
    
        /** * 计算随机数 * @return */
        private String getRandomNum(){ 
            Random random = new Random();
            String i1 = random.nextInt(999999) + "";
            StringBuffer stringBuffer = new StringBuffer();
            for (int i = 0; i < 6 - i1.length() ; i++) { 
                stringBuffer.append("0");
            }
            i1 = stringBuffer.toString() + i1;
            return i1;
        }
        @Override
        protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { 
            doGet(req, resp);
        }
    }