Where to store images in webapp?

Question

Hello.
I'm designing an web application which main purpose is to store and view images that users has stored.
I'm considering that where is the best place to store those images? I have at least two options: relational database or filesystem. Is it bad idea to store images in database? What are the downsides?
The user's images has to be seen only by the user itself, that is to say others should not get the user's private images. How this can be made by filesystem? I have thinking some kind of "ImageServlet" to where you pass image's id by parameter and the servlet checks that the requester has priviledges to fetch the image eg. is the owner of the image (fetching userinformation from the session). The application will have also a feature that the user can "share" some images to known persons. The "ImageServlet" can fulfil that requirement also.
Am I in right direction or does somebody have a better idea?
-Robert-

Answer 1

Ok maybe I do the matrix and consider the things that have been came up.
I was wondering one thing. If I choose store images in database, what about db connections? Them are anyway resources that are always scarce even if there is connection pool in use. Could that be stumbling block? Because the application's nature is, that there can be lots of pictures, users create picture albums and can view them later.
Nevertheless, I still think that I need to design some kind of "ImageServlet" to get the pics. I was wondering something like this:
In JSP/HTML page images are referenced by img tag like this
    <IMG src="ImageServlet?name=pic1" width=... height=...><BR/>
    <IMG src="ImageServlet?name=pic2" width=... height=...>
    <!-- etc -->In ImageServlet pics are served eg. like this (this is just example to show what I'm thinking)
    // check if user have rights to access to pic
    checkUserRights();
    resp.setContentType(...);
    resp.setContentLength(...);
    // imageStore could fetch the image from database or filesystem
    InputStream picStream = imageStore.getImage(req.getParameter("name"));
    OutputStream out = resp.getOutputStream();
    byte[] buf = new byte[1024];
    int count = 0;
    while ((count = pic.read(buf)) >= 0) {
      out.write(buf, 0, count);
    pic.close();
    out.close();Is there some drawbacks, if pics are sent to requester using OutputStream?