假期进度八：验证码的实现 

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

        //画干扰线
        g.setColor(Color.green);
        for (int i = 0; i <10 ; i++) {
            //随机生成坐标点
            int x1 = ran.nextInt(width);
            int x2 = ran.nextInt(width);
            int y1 = ran.nextInt(height);
            int y2 = ran.nextInt(height);
            g.drawLine(x1,x2,y1,y2);
        }


        //将图片输出到页面显示
        ImageIO.write(image,"jpg",response.getOutputStream());
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doPost(request,response);
    }
}
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script>
        /**
         * 点击超链接或图片，需要换一张
         * 给超链接和图片绑定单击事件
         * 重新设置图片的src属性值
         */
        window.onload=function () {
            //获取图片对象
            let img = document.getElementById("checkCode");
            //绑定单击事件
            img.onclick=function () {
                /**
                 * 因为浏览器会有默认缓存，如果路径不变，只会访问缓存，所以加date改变参数，保证每次都不同
                 * @type {number}
                 */
                //加时间戳
                let date=new Date().getTime();
                img.src="/day13_response/checkCodeServlet?"+date;
            }
        }
    </script>
</head>
<body>
    <img    id="checkCode" src="/day13_response/checkCodeServlet"/>
</body>
</html>

 

posted @ 2020-08-24 18:47  夜月薇凉映银弩  阅读(165)  评论(0)    收藏  举报