基础------重点摘要----验证码

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#基础------重点摘要----验证码

本文介绍了一种使用Java Servlet生成验证码的方法，包括前端页面与后端逻辑。前端通过HTML与JavaScript实现验证码刷新功能；后端通过Servlet创建带随机字符和干扰线的图片。

前端代码

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script>
       var img= document.getElementById("changImg");
        img.onclick=function () {
            img.src="/tomcat_day01/checkCode?"+new Date.getTime();
        }
    </script>
</head>

<body>
    <img id="changImg" src="/tomcat_day01/checkCode">
</body>
</html>

package cn.wjs.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;

/**
 * 验证码类实现
 */

@WebServlet("/checkCode")
public class CheckCode extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request,response);
    }
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        int width=100;
        int height=50;
        //验证码图片对象
        BufferedImage bufferedImage=new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
        //填充图片背景色
        Graphics graphics=bufferedImage.getGraphics();
        graphics.setColor(Color.pink);
        graphics.fillRect(0,0,width,height);
        //设置图片边框
        graphics.setColor(Color.blue);
        graphics.drawRect(0,0,width-1,height-1);
        //写验证码
        String code= "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghigklmnopqrstuvwxyz0123456789";
        Random rdm=new Random();
        graphics.setFont(new Font("TimesRoman",Font.BOLD,20));
        graphics.setColor(Color.BLACK);
        for (int i =1; i <=4 ; i++) {
            int i1 = rdm.nextInt(code.length());
            char c = code.charAt(i1);
            graphics.drawString(c+"",width/5*i,height/2);
        }
        //写干扰线
        graphics.setColor(Color.MAGENTA);
        for (int i = 0; i <10 ; i++) {
            int x1=rdm.nextInt(width);
            int y1=rdm.nextInt(height);
            int x2=rdm.nextInt(width);
            int y2=rdm.nextInt(height);
            graphics.drawLine(x1,y1,x2,y2);
        }


        //将图片输出到浏览器
        ImageIO.write(bufferedImage,"jpg",response.getOutputStream());
    }
}