问未知URL内容://downloads/my_downloads

EN

java.lang.IllegalArgumentException: Unknown URL content://downloads/my_downloads
   at android.content.ContentResolver.insert(ContentResolver.java:862)
   at android.app.DownloadManager.enqueue(DownloadManager.java:1252)
   at com.myapp.LessonFragment$DownloadClickListener.onClick(SourceFile:570)
   at android.view.View.performClick(View.java:4262)
   at android.view.View$PerformClick.run(View.java:17351)
   at android.os.Handler.handleCallback(Handler.java:615)
   at android.os.Handler.dispatchMessage(Handler.java:92)
   at android.os.Looper.loop(Looper.java:137)
   at android.app.ActivityThread.main(ActivityThread.java:4921)
   at java.lang.reflect.Method.invokeNative(Method.java)
   at java.lang.reflect.Method.invoke(Method.java:511)
   at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1038)
   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:805)
   at dalvik.system.NativeStart.main(NativeStart.java)

private class DownloadClickListener implements View.OnClickListener {
    @Override
    public void onClick(View view) {
        // Check if download manager available before request
        if (!DownloadHelper.isDownloadManagerAvailable(getActivity())) {
            // Build custom alert dialog
            AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
            builder.setMessage(R.string.download_manager_disabled);
            builder.setCancelable(false);
            builder.setPositiveButton(R.string.ok, (dialog, which) -> {
                dialog.dismiss();
            });
            // Create and display alert dialog
            AlertDialog dialog = builder.create();
            dialog.show();
            return;
        }

        // Display short toast on download clicked
        Toast.makeText(getActivity(), R.string.lesson_download_start, Toast.LENGTH_SHORT).show();

        // Get attach from view tag
        Attache attache = (Attache) view.getTag();

        // Get lesson using lesson id
        Lesson lesson = new Select().from(Lesson.class)
                .where(Condition.column("id").is(attache.getLessonId()))
                .querySingle();

        // Set file name from url and attache name
        Uri uri = Uri.parse(attache.getFile());
        String fileName = attache.getName() + '.'
                + MimeTypeMap.getFileExtensionFromUrl(attache.getFile());

        // Check if path directory not exist and create it
        String filePath = Environment.getExternalStorageDirectory() + "/myapp/" + lesson.getTitle() + "/";
        File path = new File(filePath);
        if (!path.exists() || !path.isDirectory()) {
            if (!path.mkdirs()) {
                Timber.e("Could not create path directory.");
            }
        }

        // Check if file exist and then delete it
        File file = new File(filePath, fileName);
        if (file.exists() && file.isFile()) {
            if (file.delete()) {
                Timber.v("%s just deleted.", fileName);
            }
        }

        // Create download manager request using url
        DownloadManager.Request request = new DownloadManager.Request(uri);
        request.setTitle(attache.getName());
        request.setDestinationInExternalPublicDir("/myapp/" + lesson.getTitle(), fileName);

        // Using DownloadManager for download attache file
        DownloadManager manager = (DownloadManager) getActivity().getSystemService(Context.DOWNLOAD_SERVICE);
        manager.enqueue(request);
    }
}