验证码案例的实现---by wjf（2020.4.6）

案例背景：在平常上网的时候，我们注册页面或者登录页面经常需要输入验证码，那么如何实现在网页上显示出这个验证码呢？又如何实现点击图片就能够进行切换验证码？

package cn.edu.mju.project1.controller;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
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("/CheckCode")
public class CheckCode extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        int width = 100;
        int height = 50;
        
        //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);

        //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);

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

        String str = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
        //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

            g.drawString(ch+"",width/5*i,height/2);//写验证码

        }



        //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);
        }


        //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);
    }
}

为了实现验证码能够通过点击图片就能切换，我在网上查阅了相关的资料，发现可以通过配置script来实现。

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script>
        //1.获取图片对象
        window.onload = function () {
            var img = document.getElementById("checkCode");
            //2.绑定单击事件
            img.onclick=function () {
                var date = new Date().getTime();//加时间戳
                img.src = "/CheckCode?"+date;

            }

        }

    </script>
</head>
<body>
    <img id="checkCode" src="/CheckCode" />

</body>
</html>

实验效果图

在这里插入图片描述

A-Jeffrey

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验证码案例的实现---by wjf（2020.4.6）

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