download(){
                this.$http({
                    url:"/getImage",
                    responseType:'blob',
                    params:{
                        path:"xxxx.com"
                    }
                }).then(
                    res => {
                        let blob = new Blob([res])
                        let downloadElement = document.createElement('a')
                        let href = window.URL.createObjectURL(blob); //创建下载的链接
                        downloadElement.href = href;
                        downloadElement.download = `x.jpg`; //下载后文件名
                        document.body.appendChild(downloadElement);
                        downloadElement.click(); //点击下载
                        document.body.removeChild(downloadElement); //下载完成移除元素
                        window.URL.revokeObjectURL(href); //释放blob对象
                    }
                )
            }

  
 @RequestMapping("/getImage")
    public void getImage(HttpServletResponse response,String path) throws IOException {
        QrConfig config = new QrConfig(300, 300);
        // 设置边距，既二维码和背景之间的边距
        config.setMargin(3);
        // 设置前景色，既二维码颜色（青色）
        config.setForeColor(Color.CYAN.getRGB());
        // 设置背景色（灰色）
        config.setBackColor(Color.GRAY.getRGB());
        // 生成二维码到文件，也可以到流
        File file = QrCodeUtil.generate(path, config, FileUtil.file("d:/img/qrcode.jpg"));

        // 下载本地文件
        String fileName = "xx.jpg"; // 文件的默认保存名
        InputStream inStream = new FileInputStream(file);// 文件的存放路径
        // 设置输出的格式
        response.setContentType("application/octet-stream");
        response.setCharacterEncoding("UTF-8");
        response.setHeader("Access-Control-Expose-Headers","Content-Disposition");
        response.setHeader("Content-Disposition", "attachment;filename=" + URLEncoder.encode(fileName,"utf-8"));
        // 循环取出流中的数据
        byte[] b = new byte[100];
        int len;
        try {
            while ((len = inStream.read(b)) > 0)
                response.getOutputStream().write(b, 0, len);
            inStream.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
        System.out.println("end");
    }