DownloadManagerで画像をダウンロードしてDownloadディレクトリに保存する

gistfile1.java

DownloadManager downLoadManager = (DownloadManager)getActivity().getSystemService(Context.DOWNLOAD_SERVICE);
DownloadManager.Request request = new DownloadManager.Request(imageUri);
request.setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS, "image.png");
File pathExternalPublicDir = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS);
pathExternalPublicDir.mkdirs();
request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
request.allowScanningByMediaScanner();
request.setAllowedNetworkTypes(DownloadManager.Request.NETWORK_MOBILE | DownloadManager.Request.NETWORK_WIFI);
downLoadManager.enqueue(request);