安卓Oreo中的下载管理器无法工作

Question

我的应用是 Cordova 混合应用程序。我安装了 这个 插件，用于从服务器(url)下载 PDF 文件。它在运行 Android 7.0 的设备上工作正常。当相同的应用程序安装在 Oreo 设备上时，什么都不会发生，并且在一段时间后，我看到“下载失败”的消息。可能的原因是什么？

我还升级了一个之前可以使用的移动设备到 8.0 并进行了测试。但是测试失败了。所以在 Oreo 操作系统下它无法工作。

private void startDownload(String message, CallbackContext callbackContext) {
        if (message != null && message.length() > 0) {
            String filename = message.substring(message.lastIndexOf("/")+1, message.length());
            try {
                filename = URLDecoder.decode(filename,"UTF-8");
            } catch (UnsupportedEncodingException e) {

                callbackContext.error("Error in converting filename");
            }
            android.app.DownloadManager downloadManager = (android.app.DownloadManager) cordova.getActivity().getApplicationContext().getSystemService(Context.DOWNLOAD_SERVICE);            
            Uri Download_Uri = Uri.parse(message);
            android.app.DownloadManager.Request request = new android.app.DownloadManager.Request(Download_Uri);
            //Restrict the types of networks over which this download may proceed.
            request.setAllowedNetworkTypes(android.app.DownloadManager.Request.NETWORK_WIFI | android.app.DownloadManager.Request.NETWORK_MOBILE);
            //Set whether this download may proceed over a roaming connection.
            request.setAllowedOverRoaming(false);
            //Set the title of this download, to be displayed in notifications (if enabled).
            request.setTitle(filename);
            //Set a description of this download, to be displayed in notifications (if enabled)
            request.setDescription("DataSync File Download.");
            //Set the local destination for the downloaded file to a path within the application's external files directory            
            request.setDestinationInExternalFilesDir(cordova.getActivity().getApplicationContext(), Environment.DIRECTORY_DOWNLOADS, filename);
            //Set visiblity after download is complete
            request.setNotificationVisibility(android.app.DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
            long downloadReference = downloadManager.enqueue(request);
            callbackContext.success(message);
        } else {
            callbackContext.error("Expected one non-empty string argument.");
        }
    }

- NewOne

---

在模拟器上尝试还是在物理设备上？ - Cyph3rCod3r

物理设备。所有测试都在物理设备上进行。 - NewOne

Answer 1

请确保在Menifest.xml文件中添加了此权限

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

and use the following code

 DownloadManager.Request request = new DownloadManager.Request(
            Uri.parse(url));

    request.allowScanningByMediaScanner();
    request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED); //Notify client once download is 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", //To notify the Client that the file is being downloaded
            Toast.LENGTH_LONG).show();

- Humxa Moghal