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Linking and copying an external (Removable storage) file in android

I have an open question I would like to ask before starting development of functionality, only to learn more about the subject afterwards, just to start all over again ;) I tried searching, but am not really sure what to search for. Therefor, I would like to pick your brains a bit here...

Here is the current situation: I have an app that stores activity/event logs. In a simplified example: "Person A filled a glass with 100ml of water"

This is stored as a record in a single table.

Now, for the requirement of the new functionality: I connect an external storage device via USB to my tablet. On this storage device there are several text files. Each file contains parameters of an activity/event, similar to the one described above, but with different data.

I would like to create a function to import these files, read some of their content into the database as new records, and then store the file somewhere on the tablet, with a link to the file as a field in the DB. Ideally I would have liked to store the contents of the entire text file in a field, or a field in a related 1:1 table, but these files could be as big as 1MB (1MB would be very rare, but possible. Avg is around 100KB).

So, my questions are:

  • Is it at all possible to copy a file from an external storage device, linked via USB, to the android device's SD card/internal memory? (I can access this storage device using a file explorer app on my tablet)
  • If so, what is the best way to go about this?
  • If not, what are my alternatives?
  • Also, if not possible to copy and locally store the files, is it still possible to access their contents on the external storage? In which case I will then just import the data I need, and not store a copy of the original file.

Thanks in advance, all replies are much appreciated!

Solution

  • No one wants to take the chance? :)

    For future readers with the same problem: It is possible to read a file from a usb connected device. Keep in mind that reading the file directly from the file system is different than reading it as an attachment in a mail for instance. Not much more than a different path though ;)

    I ended up reading the file into a DB, splitting the lines across a record. In other words, not adding the whole file (or even a complete line) in a field, but rather parsing the file into a single record, split up into various fields.

    Two things I came across that might help you. Reading a file is pretty fast, but do not make the mistake I made by writing these lines to the database one by one. Better to add them all to a transaction, and commit at once. The other, you can use a read buffer to read the file, instead of the default inputstream. This also speeds up reading of large files.