从动态站点使用WebView Android下载文件

Question

WebView无法从URL下载文件：

https://www.ecogas.com.ar:444/appweb/iris/app/jano/dm/isu_lecturistas_descarga.php?d=2399&f=70b9aa50d872681415ad7f8dade8fc39&ext=txt

webView.setDownloadListener(new DownloadListener()
{
    @Override
    public void onDownloadStart(String url, String userAgent,
                                String contentDisposition, String mimeType,
                                long contentLength) {
        String fileName;
        try {
            DownloadManager.Request request = new DownloadManager.Request(Uri.parse(url));
            request.setMimeType(mimeType);
            String cookies = CookieManager.getInstance().getCookie(url);
            request.addRequestHeader("Cookie", cookies);
            request.addRequestHeader("User-Agent", userAgent);
            request.addRequestHeader("Accept", "text/html, application/xhtml+xml, *" + "/" + "*");
            request.addRequestHeader("Accept-Language", "en-US,en;q=0.7,he;q=0.3");
            request.addRequestHeader("Referer", url); // Use the same file name for the destination
            request.setDescription("Downloading File...");
            request.setTitle(URLUtil.guessFileName(url, contentDisposition, mimeType));
            request.allowScanningByMediaScanner();
            request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
            request.setDestinationInExternalPublicDir(
                    Environment.DIRECTORY_DOWNLOADS, URLUtil.guessFileName(
                            url, contentDisposition, mimeType));
            DownloadManager dm = (DownloadManager) getSystemService(DOWNLOAD_SERVICE);
            dm.enqueue(request);
            Toast.makeText(getApplicationContext(), "Downloading File: " + url, Toast.LENGTH_LONG).show();
            etNotificacion.setText(url);
        }catch (Exception e){
            Toast.makeText(getApplicationContext(), e.getMessage(), Toast.LENGTH_LONG).show();
        }
    }});