I wrote Dynamic Tree Framework - with it you can view most of things
you need (except files in databases).
The bad news is that I there are no way to use it with java's JFileChooser.
The good news is that you can use it with simple JTree and you can easy
implement your own handler (for example for database).

see tutorial
http://jgui.imagero.com/tutorial.html#explore
http://jgui.imagero.com/tutorial.html#browseURL
http://jgui.imagero.com/tutorial.html#browseANY

and javadoc
http://jgui.imagero.com/doc/com/imagero/gui/swing/tree/package-summary.html
http://jgui.imagero.com/doc/com/imagero/gui/swing/tree/handler/package-summary.html
http://jgui.imagero.com/doc/com/imagero/gui/swing/tree/node/package-summary.html
http://jgui.imagero.com/doc/com/imagero/gui/swing/tree/util/package-summary.html

it is part of JGui (JGui 1.38 is open source - GPL)
download here http://jgui.imagero.com/download.php

Another (may be better) way could be to create interface (e.g. VirtualFile)
and implement it.

For one project I started with following:

public interface VFile {
   String getName();
   String getDisplayName();    //for specific things (like desktop in
windows)
   String getParent();
   VFile getParentFile();
   String getAbsolutePath();
   boolean isDirectory();
   boolean isHidden();
   String [] list();
   String [] list(VFilenameFilter filter);
   VFile create(String name);    //create child with specified name
   boolean exists();
   int getPos();    //for sorting purposes
   InputStream getInputStream() throws VFileNotFoundException;
   OutputStream getOutputStream() throws IOException;
}

I implemented it currently only for standalone files, but want to add
implementation for database.