As I said in my comment, viewing a file requires downloading it.
What you might mean, is that you don't want to store it.
The problem is that the Android intent system doesn't offer this degree of flexibility, which is usually a good thing. You tell it to view a file, and it does that with whatever app it can. And there's no problem with storing it, you have to store it. The problem is where you store it. To view it, you have to at least store it in memory, storing it as an Android managed temporary file could also fulfill your need, and what's wrong with just storing it somewhere else and deleting it afterwards?
If you really need to store it to a custom place you'll have to leave the intent system and do the downloading yourself.