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From: Martin Gregorie <martin@address-in-sig.invalid>
Newsgroups: comp.lang.java.programmer
Subject: Re: Resource confusion
Date: Tue, 31 Jan 2012 02:45:25 +0000 (UTC)
Organization: UK Free Software Network
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On Mon, 30 Jan 2012 13:33:30 -0800, Roedy Green wrote:

> On Sat, 28 Jan 2012 17:47:48 +0000 (UTC), Novice <novice@example..com>
> wrote, quoted or indirectly quoted someone who said :
> 
>>I'm having trouble figuring out the best way of obtaining existing files
>>for my program to use.
> 
> I would put the read-only config files in a resource in a jar.  This
> means they can't get lost and they work even if the user is not capable
> of configuring his own files. They are also compact. They get updated
> automatically when you update the program.
> 
> You problem then becomes, where to put the user's files.  JNLP lets you
> allocate some space with a hideous name, not really suitable for the
> user to insert things except via your game.  If he creates them with a
> text editor you might import them into that space or store the filenames
> (not files) in your own space so he can pick them off a menu by
> unqualified name, and you then go fetch them from the original locations
> as needed.
>
Same here: I'd put the defaults in the jar and, allow the user to put 
overriding files in a master location and a one local to the user: if it 
was a UNIX type system the master location would be /usr/local/etc and 
the local location would be the hidden directory ~/.myapp and the program 
would use a search something like this; 

 List<String> config = new List<String>();
 config.add("~/.myapp/config.txt");
 config.add("/usr/local/etc/config.txt");

 boolean found = false;
 for (String s : config)
 {
   File cf = new File(s);
   if (cf.exists())
   {
     found = true;
     // use the configuration in cf
   }
 }

 if (!found) 
   // use the default configuration held as a resource in the jar file
 
which lets the user's configuration take preference over the site 
configuration in /usr/local/etc, which in turn takes precedence over the 
jar file resource.

NOTE: this assumes that each configuration is complete.

Another way to do it is to read all three config files in the *reverse* 
order (from jar file, then /usr/local/etc and finally from ~/.myapp) with 
items read from an earlier file being overwritten by matching items from 
a later file. This approach means that the config in the jar file must 
give a default value for every item, but the site and user configurations 
only need to provide values for items they want to customise.
   

-- 
martin@   | Martin Gregorie
gregorie. | Essex, UK
org       |