文件名称乱码，content-disposition 获取filename乱码的解决办法

1. 前端先确认是否能在响应头里获取到filename 。如果获取不到，需后端服务器设置请求头Access-Control-Expose-Headers

    /**
     * 设置headers
     * name 文件名称 "中国.xlsx"
     */
    public static HttpHeaders getHeaders(String name) {
        HttpHeaders headers = new HttpHeaders();
        //配置Access-Control-Expose-Headers，暴露Content-Disposition
        List<String> list = new ArrayList<>(2);
        list.add("Content-Disposition");
        headers.setAccessControlExposeHeaders(list);
        try{
            headers.set("Content-Disposition",     "attachment;filename="+URLEncoder.encode(name,"UTF-8"));
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }
        return headers;
    }

2. 后台服务器设置Content-Disposition，对文件名称转码

        第一种：

URLEncoder.encode(name,"UTF-8")

        第二种：

new String(name.getBytes("GBK"),"ISO-8859-1"))

3. 后台服务端设置完毕。再看前端，对filename进行解码操作

const fileName = decodeURI(res.headers.get('content-disposition')).split('filename=')[1]