Reading resource files from a jar file
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From: Roedy Green on 12 Feb 2010 13:53 On Fri, 12 Feb 2010 14:55:08 +0000 (UTC), Martin Gregorie <martin(a)address-in-sig.invalid> wrote, quoted or indirectly quoted someone who said : >I have a configuration file intentionally buried in a jar file I'm >building (and a tool to amend it before you ask). This is all working >correctly but could possibly have been done better. see http://mindprod.com/jgloss/resource.html and http://mindprod.com/jgloss/image.html for a number of examples. The trickiest part is deciding whether to put the resource in a package or in the root, then looking in the right place for it. -- Roedy Green Canadian Mind Products http://mindprod.com Every compilable program in a sense works. The problem is with your unrealistic expections on what it will do.
From: John B. Matthews on 12 Feb 2010 16:14 In article <hl44u0$p9k$1(a)localhost.localdomain>, Martin Gregorie <martin(a)address-in-sig.invalid> wrote: > On Fri, 12 Feb 2010 12:24:48 -0500, John B. Matthews wrote: > > > In article <hl411c$6f$2(a)south.jnrs.ja.net>, > > Nigel Wade <nmw(a)ion.le.ac.uk> wrote: > > > >> On Fri, 12 Feb 2010 14:55:08 +0000, Martin Gregorie wrote: > >> > >> > I have a configuration file intentionally buried in a jar file I'm > >> > building (and a tool to amend it before you ask). This is all working > >> > correctly but could possibly have been done better. > >> > > >> > Yesterday I searched for documentation on doing this type of thing > >> > but couldn't find anything in the standard Java 6 documentation. > >> > Embarrassingly, I can't even find the description of how to set it up > >> > that I used in the first place. I'm probably missing something > >> > obvious, so pointers on where to find this information would be most > >> > welcome. > >> > > >> > The reason I need the documentation: I can write code that uses an > >> > InputStream to read the configuration file provided its in the same > >> > package as the class that reads it, but would prefer to put the file > >> > in the root of the jar file. Is it mandatory for the file to be in > >> > the same package as its reader or is there a way of accessing it when > >> > its placed elsewhere? > >> > >> Specify a class within the relevant jar as the "reference" for > >> getClass, then use an absolute path for the resource itself. > > > > Here's an example: > > > > <http://robotchase.svn.sourceforge.net/viewvc/robotchase/trunk/src/org/ > gcs/robot/RCImage.java?revision=64&view=markup> > > So the 'absolute path' takes the class's package as its root. Gotcha. Empirically, yes. It's my best interpretation of the getResource() API: <http://java.sun.com/javase/6/docs/api/java/lang/Class.html#getResource(java.lang.String)> -- John B. Matthews trashgod at gmail dot com <http://sites.google.com/site/drjohnbmatthews>
From: Lew on 12 Feb 2010 17:52 Martin Gregorie <martin(a)address-in-sig.invalid> wrote: >> So the 'absolute path' takes the class's package as its root. Gotcha. John B. Matthews wrote: > Empirically, yes. It's my best interpretation of the getResource() API: > > <http://java.sun.com/javase/6/docs/api/java/lang/Class.html#getResource(java.lang.String)> I think you have that backwards. AIUI, an absolute resource path (starts with '/') is relative to the class path, and a relative path (doesn't start with '/') is relative to the "modified_package_name". I am citing from the link provided. Plus, when I've run tests, I've observed behavior consistent with my interpretation. The wiggle room comes from "The rules for searching resources associated with a given class are implemented by the defining class loader of the class." So class loaders can change these rules. -- Lew
From: Daniel Pitts on 12 Feb 2010 18:13 On 2/12/2010 6:55 AM, Martin Gregorie wrote: > I have a configuration file intentionally buried in a jar file I'm > building (and a tool to amend it before you ask). This is all working > correctly but could possibly have been done better. > > Yesterday I searched for documentation on doing this type of thing but > couldn't find anything in the standard Java 6 documentation. > Embarrassingly, I can't even find the description of how to set it up > that I used in the first place. I'm probably missing something obvious, > so pointers on where to find this information would be most welcome. > > The reason I need the documentation: I can write code that uses an > InputStream to read the configuration file provided its in the same > package as the class that reads it, but would prefer to put the file in > the root of the jar file. Is it mandatory for the file to be in the same > package as its reader or is there a way of accessing it when its placed > elsewhere? > > There is Class.getResource*, but you probably want ClassLoader.getResource* My understanding is that The Class.getResource looks in the same package as the class, where ClassLoader.getResource looks relative to the class-path roots which it knows about. -- Daniel Pitts' Tech Blog: <http://virtualinfinity.net/wordpress/>
From: Lew on 12 Feb 2010 18:45
On 2/12/2010 6:13 PM, Daniel Pitts wrote: > There is Class.getResource*, but you probably want ClassLoader.getResource* > > My understanding is that The Class.getResource looks in the same package > as the class, where ClassLoader.getResource looks relative to the > class-path roots which it knows about. See the link provided by John B. Matthews and the corresponding entry in the 'ClassLoader' Javadocs. The 'Class' version's behavior depends on the presence or absence of a leading '/' (slash) in the resource path. Without the leading slash, the resource is found relative the class's package, with the slash it's to the class path. -- Lew |