CODEWITHSUNDEEP
javaservletshash
urobo
urobo

Reputation: 786

Store images with unique filenames using hashing

I'm looking for a solution for storing unique file names for a web application using Java Servlet.

What I need is to render profile images in a webpage, since I decided to store only file names in the database I have only to be sure they're unique in the image folder: to achieve that I was thinking to name images and save them with a string name composed by the couple:

<user_id>_<hash>.<file-type>

In this manner I think I would be pretty sure there will be no collisions, since user_ids are already unique.

1) Is this solution sound?

2) What algorithm should I pick for this purpose?

I'd like to use it properly so code snippets would be very appreciated.

Thanks

Upvotes: 1

Views: 2081

Answers (3)

Shawn Mclean
Shawn Mclean

Reputation: 57479

Why attach a hash or anything to it if its a 1 to 1 mapping? 1 user to 1 profile image, just use their id. If its a 1 to many, save the record in the database and get the id of that record and use that as the name. You might want to convert all your images to a particular image format too just to be consistent, so that wouldn't be stored in your database either.

BalusC tempfile method would work perfectly with this presented concept.

Upvotes: 0

BalusC
BalusC

Reputation: 1109432

You can use File#createTempFile() wherein you specify the prefix, suffix and folder. The generated filename is guaranteed to be unique. 

File file = File.createTempFile("name-", ".ext", new File("/path/to/uploads"));
// ...

No, this file won't be auto-deleted on exit or something, it's just a part of temp file generation mechanism.

Upvotes: 3

DaveH
DaveH

Reputation: 7335

Really simple approach would be to append System.currentTimeMillis() to the userid. If userid is unique then it should be pretty safe.

Upvotes: 2

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