JavaWeb 实现简单的验证码

后端

package cn.itcast.web.servlet;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.annotation.WebServlet;
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;

@WebServlet("/checkCodeServlet")
public class CheckCodeServlet extends HttpServlet {
    
    
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    
    

        int width = 100;
        int height = 50;

        //1.创建一对象，在内存中图片(验证码图片对象)
        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

        //2.美化图片
        //2.1 填充背景色
        Graphics g = image.getGraphics();//画笔对象
        g.setColor(Color.PINK);//设置画笔颜色
        g.fillRect(0, 0, width, height);

        //2.2画边框
        g.setColor(Color.BLUE);
        g.drawRect(0, 0, width - 1, height - 1);

        String str = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghigklmnopqrstuvwxyz0123456789";
        //生成随机角标
        Random ran = new Random();

        for (int i = 1; i <= 4; i++) {
    
    
            int index = ran.nextInt(str.length());
            //获取字符
            char ch = str.charAt(index);//随机字符
            //2.3写验证码
            g.drawString(ch + "", width / 5 * i, height / 2);
        }


        //2.4画干扰线
        g.setColor(Color.GREEN);

        //随机生成坐标点

        for (int i = 0; i < 10; i++) {
    
    
            int x1 = ran.nextInt(width);
            int x2 = ran.nextInt(width);

            int y1 = ran.nextInt(height);
            int y2 = ran.nextInt(height);
            g.drawLine(x1, y1, x2, y2);
        }


        //3.将图片输出到页面展示
        ImageIO.write(image, "jpg", response.getOutputStream());


    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    
    
        this.doPost(request, response);
    }
}

前端

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script>
        /*
            分析：
                点击超链接或者图片，需要换一张
                1.给超链接和图片绑定单击事件
                2.重新设置图片的src属性值
         */
        window.onload = function () {
      
      
            //1.获取图片对象
            var img = document.getElementById("checkCode");
            //2.绑定单击事件
            img.onclick = function () {
      
      
                //加时间戳
                var date = new Date().getTime();

                img.src = "/项目名/checkCodeServlet?" + date;
            }

        }

        function f() {
      
      
            var img = document.getElementById("checkCode");
            var date = new Date().getTime();
            img.src = "/项目名/checkCodeServlet?" + date;

        }
    </script>
</head>

<body>
    <img id="checkCode" src="/项目名/checkCodeServlet"/>
    <a href="javascript:void(0);" onclick="f()">看不清换一张？</a>
</body>

</html>

JavaWeb 实现简单的验证码

后端

前端

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