验证码

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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 {
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //设置图片的大小
        int width = 100 ;
        int height = 50 ;
        //1.创建一个对象,在内存中的图片(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 = "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
            //2.3写验证码
            g.drawString(ch+"",width/5*i,height/2);
        }


        //画干扰线
        g.setColor(Color.GREEN);
        for (int i = 1; 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,y1,x2,y2);
        }

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


    }

    @Override
    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>
        window.onload = function () {
            //1.获取图片对象
            var img = document.getElementById("checkcode");
            //2.绑定单机事件
            img.onclick = function () {
                //时间戳
                var date = new Date().getTime();
                img.src= "/day15/checkCodeServlet?"+date;
            }

        }
    </script>
</head>
<body>
<img id="checkcode" src="/day15/checkCodeServlet" >
<a id="change" href="">看不清换一张?</a>
</body>
</html>

 

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