Android Webview 仅下载 HTML 格式的文件

Question

我是Android开发的新手。我正在使用WebView，并且网站上有PDF文件供下载。但是用户需要登录以访问可下载的内容。我使用以下代码，下载和文件命名非常完美。但是，在每次下载中，文件类型都成为HTML，而HTML仅显示一个带有错误404的网页。请帮助我解决此问题。

 webView.setDownloadListener(new DownloadListener()
   {

  @Override  


   public void onDownloadStart(String url, String userAgent,
        String contentDisposition, String mimeType,
        long contentLength) {

    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.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",
            Toast.LENGTH_LONG).show();
}});