Save file in mysql database using Hibernate

Question

I'm trying to figure out the 'correct', failsafe way to save/retrieve files in a mysql database using Hibernate. The solution has to work with files that are quite large, so minimizing the memory footprint would be important.

My solution, so far:

A model class containing a java.sql.Blob field, the getter annotated with "@Lob".

public static void main(String[] args) {
    DAOFactory factory = DAOFactory.getFactory();
    IResultExtraDAO resultExtraDAO = factory.getResultExtraDAO();
    factory.getResultExtraDAO().beginTransaction();

    ResultExtra resultExtra = new ResultExtra();
    LobHelper lh = HibernateUtil.getSession().getLobHelper();
    try {
        File file = new File("/3030.jpg");
        FileInputStream fis = new FileInputStream(file);
        Blob b = lh.createBlob(fis, fis.available());
        resultExtra.setFile(b);
    } catch (Exception e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

    resultExtraDAO.save(resultExtra);

    factory.getResultExtraDAO().commitTransaction();
}

Is this the correct way to do it? Whould there be a risk of running out of memmory if there are manny simultanious uploads and/or large files? Is there another solution that would be better?

Also, I'm using the 'Generic Data Access Object' pattern encapsule hibernate, so I don't like accessing the HibernateUtil directly as I do here, but so far I haven't figured out a good generic way to access it. Suggestions are welcome.

brent777 · Accepted Answer · 2011-03-07 21:33:04Z

1

Storing the files as a Blob in your DB will work. However, this can become a bit of an issue as you start to get more and more such files in your DB. Depending on the volume of files that you expect, I would recommend that you consider not storing said files in your DB at all.

Perhaps consider storing them in a content repository, like Jackrabbit. These files are then accessible via a URL that tells you where they are in the repository.

So to summarise, if you really want the files in your DB then what you have sounds fine you may just want to ensure that you have Hibernate lazy-load these blobs especially if they can get quite big. However, I would recommend that you at least consider a content repository.

answered Mar 7, 2011 at 21:33

brent777

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5 Comments

Holm Over a year ago

@brent777 Thanks for your input, will take a look at Jackrabbit. If there are no more answers in the following days I will mark your answer as accepted.

Holm Over a year ago

Also, what's the biggest advantage of using a content repos rather than storing the files in the local file system directly?

brent777 Over a year ago

There are quite a few advantages, since I am a little lazy right now I will leave you with the following list of advantages from the Jackrabbit Wiki :)

brent777 Over a year ago

"The main advantages of the data store over the blob store are: unlike the blob store, the data store keeps only one copy per object, even if it is used multiple times. The data store detects if the same object is already stored and will only store a link to the existing object. The data store can be shared across multiple workspaces, and even across multiple repositories if required. Data store operations (read and write) don't block other users because they are done outside the persistence manager. Multiple data store operations can be done at the same time."

brent777 Over a year ago

I hope that answers your question @Holm

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