Uri Access Lifetime: Shorter Than You Might Think
Your app gets a
Uri from some outside source. Perhaps you used
ACTION_OPEN_DOCUMENT to get a
Uri to some
user-selected content. Perhaps you have an activity with an
set up to respond to
ACTION_SEND or something, and
you got a
Uri that way.
How long can you use that
Uri to access the content that it points to?
Some developers think that you have indefinite access to it, and that
Uri value can be saved safely to persistent storage. For a
Uri, that might almost work, though the file could always be moved
However, you do not have long-term access to the content
identified by a
Uri. It is best to think of a
as being akin to an HTTPS URL to some content, where that content can
only be accessed if the session is authenticated (e.g., via a session
cookie). Just because you can download content from that URL today does
not mean that you can download content from that URL tomorrow, as the
session may well have timed out.
So, how long do we have for
I always thought that access was scoped to the lifetime of your process. It turns out that I was wrong, and that it’s much shorter than I had been thinking.
Ian Lake pointed out
that access is tied to the component that received the
that component is destroyed, access to the content identified by
For example, suppose that you use
ACTION_OPEN_DOCUMENT to allow the
user to pick a document via the Storage Access Framework. That has
to be done by an activity, using
startActivityForResult(), where you
onActivityResult(). You can use that
from within that activity instance. Once that activity is destroyed,
though, you can no longer access the content identified by the
If you need incrementally longer access — say, long enough for you to process the content — the recipe is:
Use a service for doing that processing work
Urito the service via the data facet of the
FLAG_GRANT_WRITE_URI_PERMISSIONto the flags for the
Now the service will have access to the content identified by the
until the service is destroyed (or until the service uses similar techniques
to pass access along to some other component).
Uri via an extra should also work on Android 5.0+, though
I have not tried that with this specific scenario)
If you need durable access — such as being able to access the content tomorrow — you have two main options that I know of:
If you used
ACTION_CREATE_DOCUMENT, or similar Storage Access Framework mechanisms, you can try using
ContentResolverto get long-term access to the content.
Otherwise, before your component is destroyed, make a local copy of the content in your app’s portion of internal storage. This approach sucks, as it duplicates the content, and changes to the original edition of the content will not be reflected in the copy. Use appropriate UI terms (e.g., “import”) to help the user understand that this is what is going on.
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