简单验证码生成（基于HTML+Servlet）-蒲公英云

简单验证码生成（基于HTML+Servlet）

叁歲伎倆 2023-10-07 11:14 102阅读 0赞

1.需求介绍

本文是一个基于Servlet+HTML实现的简单的验证码生成案例，高级的验证码也都是通过基础的验证码实现上改进过来的，此案例可帮助了解生成验证码的原理。

2.代码实现

Servlet代码

package com.servlet;
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("/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）
        BufferedImage image = new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
        //2.美化图片
        //2.1背景色填充
        Graphics g = image.getGraphics();//设置画笔对象
        g.setColor(Color.YELLOW);//画笔颜色
        g.fillRect(0,0,width,height);
        //2.2画边框
        g.setColor(Color.RED);
        g.drawRect(0,0,width-1,height-1);
        String str = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
        //创建随机数
        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);
        //生成随机坐标点
        for (int i = 1; i <=5 ; 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);
    }
}

HTML代码

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>验证码</title>
</head>
<script>
    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 = "/day04/checkCodeServlet?"+date;//保证验证码每次访问都会刷新
    }
    }
</script>
<body>
    <img id="checkCode" src="/day04/checkCodeServlet" />
    <a id="change" href="">看不清换一张</a>
</body>
</html>