In SDK 29 (Aka Android_Q), The access to external storage using the method Environment.getExternalStorageDirectory()
is deprecated and no longer returns an accessible file.
getExtenalStoragePublicDirectory(String type)
This method was deprecated in API level 29. To improve user privacy,direct access to shared/external storage devices is deprecated. When an app targets Build.VERSION_CODES.Q, the path returned from this method is no longer directly accessible to apps. Apps can continue to access content stored on shared/external storage by migrating to alternatives such as Context#getExternalFilesDir(String), MediaStore, or Intent#ACTION_OPEN_DOCUMENT.
But using Context#getExternalFilesDir(String)
returns a folder inside your App-Data folder. Which is deleted on your app’s uninstallation or data clearing.
But consider how app likes WhatsApp or Facebook Messenger save their backups and downloads, they use external storage and create their custom folders to store their data.
How will such apps migrate? Is there a new way?
My app is a notes application that backs-up all the notes into a folder for later restoration after app deletion or data clearing. In SDK 29, I can no longer follow such a method.
2
Answers
Use
ACTION_OPEN_DOCUMENT_TREE
to allow the user to pick a document tree, which could be a filesystem directory or something else. Then, useDocumentFile.fromTreeUri()
to create aDocumentFile
for that tree and use that to be able to write to documents to be stored inside of that tree.ACTION_OPEN_DOCUMENT
andACTION_OPEN_DOCUMENT_TREE
will be the two most likely on-device options. In the case of WhatsApp and Facebook, they might just elect to store the backups on their servers.You can use the flag
android:requestLegacyExternalStorage="true"
in your manifest file.This attribute is “false” by default on apps targeting Android 10 or higher.
However, in future versions of Android, this permission will not be available.
For next Android versions we should use scoped storage.
More info here