Java swing生成图片验证码

package com.donleo.ssm.common;


import com.donleo.ssm.utils.CommonPath;
import redis.clients.jedis.Jedis;

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.io.OutputStream;
import java.util.Random;

/**
 * @author liangd
 * date 2020-10-16 11:31
 * code 生成验证码图片
 */
@WebServlet("/code")
public class CodeServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //创建空白图片
        BufferedImage image = new BufferedImage(90, 30, BufferedImage.TYPE_INT_RGB);
        //1.获取图片画笔
        Graphics g = image.getGraphics();
        Random r = new Random();//随机数
//        r.nextInt(255)，随机数在0到255之间 而且必须是整数
        //2.设置画笔颜色
//        设置背景颜色，RGB 三个参数
        g.setColor(new Color(r.nextInt(255), r.nextInt(255), r.nextInt(255)));
        //3. .绘制矩形的背景
        g.fillRect(0, 0, 90, 30);


        //4.调用自定义的方法,获取长度为5的字母数字组合的字符串
        String number = getNumber(5);
//        System.out.println(number);
        req.getSession().setAttribute("code", number);
        Jedis jedis = new Jedis();
        jedis.auth(CommonPath.REDIS_AUTH.getValue());
        jedis.set("backCode",number);
        g.setColor(new Color(0, 0, 0));
        g.setFont(new Font("宋体", Font.BOLD, 24));
        //5.设置颜色字体后，绘制字符串
        g.drawString(number, 5, 25);
        //6.绘制8条干扰线
        for (int i = 0; i < 18; i++) {
            g.setColor(new
                    Color(r.nextInt(255), r.nextInt(255), r.nextInt(255), r.nextInt(255)));
            g.drawLine(r.nextInt(90),
                    r.nextInt(30),
                    r.nextInt(90),
                    r.nextInt(30));
//            直线参数 （a,b,x,y),a,b代表起点，x，y代表终点
        }
        resp.setContentType("image/ jpeg");
        OutputStream ops = resp.getOutputStream();
        ImageIO.write(image, "jpeg", ops);
        ops.close();

    }

    /**
     * 字符串的拼接
     *
     * @param size
     * @return
     */
    private String getNumber(int size) {
        //把I和O都去掉，因为和1,0不好识别
        String str = "ASDFGHJKLQWERTYUIOPZXCVBNM";
        StringBuilder number = new StringBuilder();
        Random r = new Random();
        for (int i = 0; i < size; i++) {
            number.append(str.charAt(r.nextInt(str.length())));
//            str.charAt 拿到下标为0-str长度之间的下标，下标从0开始
        }
        return number.toString();
    }
}