前端页面获取不到servlet传来的图片

问题遇到的现象和发生背景

用代码块功能插入代码，请勿粘贴截图

前端页面：

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
  <head>
    <title>$Title$title>
  head>
  <body>
  <link href="favicon.ico" rel="shortcut icon">
  <form method="post">
    用户名<input type="text" name="username"><br>
    密码:<input type="password" name="pwd"><br>
    验证码：<input type="text" name="code"><img src="/session/CheckCode"><br>
    <input type="submit" value="登录">
  form>
  body>
html>

servlet页面：

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("/CheckCode")
public class CheckCodeServlet  extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        int width=100,height=30;
        //在内存中生成图片
        BufferedImage bufferedImage=new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
        //得到画笔
        Graphics graphics = bufferedImage.getGraphics();
        //设置画笔颜色
        graphics.setColor(Color.yellow);
        //填充背景色
        graphics.fillRect(0,0,width,height);
        //设置边线
        graphics.setColor(Color.black);
        graphics.drawRect(0,0,width,height);
        //随机生成验证码，在图片上画验证码
        String str="QWERTYUIOPASDFGHJKLZXCVBNMqwertyuiopasdfghjklzxcvbnm";
        Random random=new Random();
        graphics.setColor(Color.red);
        for (int i=1;i<=4;i++){
            char ch=str.charAt(random.nextInt(str.length()));//随机取字符
            //把字符画到图片上
            graphics.drawString(ch+"",width/5*i,height/2);
        }
        //画干扰线
        graphics.setColor(Color.gray);
        for (int i=0;i<=5;i++){
            int x1=random.nextInt(width);
            int x2=random.nextInt(height);
            int y1=random.nextInt(width);
            int y2=random.nextInt(height);
            //画线
            graphics.drawLine(x1,x2,y1,y2);
        }
        //把图片发送给客户端
        ImageIO.write(bufferedImage,".jpg",resp.getOutputStream());
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req,resp);
    }
}

运行结果及报错内容

运行结果为图片裂开，开发者工具显示没有报错信息

你是不是应该打断点看啊