我在android中使用DownloadManager API成功下载了一个pdf文件.

正确设置清单权限.
文件下载正确.

但当试图打开它时说“无法打开文件”.

请帮忙打开下载的文件.我想我没有为文件设置正确的名称和扩展名.怎么设置呢？

private void DownloadBook(String url,String title){
    DownloadManager.Request request = new DownloadManager.Request(Uri.parse(url));
    //request.setDescription("Some descrition");
    String tempTitle = title.replace(" ","_");
    request.setTitle(tempTitle);
    // in order for this if to run,you must use the android 3.2 to compile your app
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
        request.allowScanningByMediaScanner();
        request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
    }
    request.setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS,tempTitle+".pdf");
    // get download service and enqueue file
    DownloadManager manager = (DownloadManager) getSystemService(Context.DOWNLOAD_SERVICE);
    request.setMimeType(".pdf");
    request.allowScanningByMediaScanner();
    request.setAllowedNetworkTypes(DownloadManager.Request.NETWORK_MOBILE | DownloadManager.Request.NETWORK_WIFI);
    manager.enqueue(request);
}