Android: upload files totally in background
This library - https://github.com/gotev/android-upload-service 2.3K stars Apr 2020
" -Easily upload files (Multipart/Binary/FTP out of the box) in the background with progress indication notification
-upload files to a server with FTP, HTTP multipart/form-data or binary requests
-handle multiple concurrent uploads in the background, even if the device is idle (Doze mode)
-automatically retry failed uploads, with a configurable exponential backoff possibility to automatically delete uploaded files when the upload is successful
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...
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You should use Service
for this purpose. It will be running on background, and in it you can do all your upload/download work. You can look at this tutorial, and also read more about it from official documentation here and here.
You can just move all your logic from Activity
/Fragment
to Service
, and it will be do it in background, even if your app is closed.