Re: Declaring Java classes and methods -- JAVA400-L

Sudha,

that is the similar thing to what I usually do.

I create a single record file 1000 chars long and read the classpath in from
that.
i just thought there might be cleaner way to load lots of jar files that
reside in a directory.

Heres the link to the custom classloader stuff.

http://www-106.ibm.com/developerworks/java/library/j-dyn0203.html

The class you create will subclass URLClassloader.
To load all the jars in a classpath, you just read them in from directory
and call addUrl to add the to the custom classloaders classpath

eg this code will add the jars in a list of directories to the classpath

 class JarFilter implements FilenameFilter {
     public boolean accept(File dir, String name) {
         return (name.endsWith(".jar"));
     }
 }


     // Create filter if necessary
     if (jf == null)
      jf = new JarFilter();

     String lib = null;

     StringTokenizer st = new StringTokenizer(liblist,":");
     while (st.hasMoreTokens()) {
         lib = st.nextToken();

      // Get a list of jars in the directory
      File dir = new File(lib);

      // Exit if directory not found
      if (!dir.exists())
      {
       throw new Exception(dir.getAbsolutePath() + " not found in
addJarLib");
      }

      File[] files = dir.listFiles(jf);
      if (files.length == 0)
      {
             addURL(dir.toURL());
      }
      else
      {
          for (int i = 0; i < files.length; i++) {
                 addURL(files[i].toURL());
       }
      }
     }

cheers
Colin.W




----- Original Message ----- 
From: <SRamanujan@xxxxxxxxxxxxxxxxxx>
To: <java400-l@xxxxxxxxxxxx>
Sent: Monday, August 30, 2004 8:58 PM
Subject: RE: Declaring Java classes and methods


> Hi Colin,
> I usually write a clle that sets up the class path env variable with the
> desired paths passed in from command.  But am curious about the custom
> classloader. Where can I find info on this?
> Thanks,
> Sudha
>
> Sudha Ramanujan
> SunGard Futures Systems
> sramanujan@xxxxxxxxxxxxxxxxxx
> (312) 577 6179
> (312) 577 6101 - Fax
>
> -----Original Message-----
> From: colin williams [mailto:colin.williams@xxxxxxxxxxxx]
> Sent: Monday, August 30, 2004 2:26 PM
> To: Java Programming on and around the iSeries / AS400
> Subject: Re: Declaring Java classes and methods
>
> Joe,
>
> if you need to write a custom classloader, there are some articles on
> the
> IBM developerworks site that discuss this(assuming you havent done this
> before!).
>
> I recently knocked up a custom classloader so that i could setup my
> classpath dynamically, rather than setting using the RUNJVA command.
>
> I had an application that used a component dependent on a lot of open
> source
> JARS, and I didnt want to type them all in to the classpath one by one.
> So I created custom classloader that I could point at a directory, and
> it
> would add all the jars to the classpath.
>
> cheers
> Colin.W
>
> ----- Original Message ----- 
> From: <furgalj@xxxxxxxxxxxxxxxx>
> To: <java400-l@xxxxxxxxxxxx>
> Cc: <java400-l@xxxxxxxxxxxx>; <java400-l-bounces@xxxxxxxxxxxx>
> Sent: Monday, August 30, 2004 3:36 PM
> Subject: Re: Declaring Java classes and methods
>
>
> > Joe Pluta wrote:
> >
> > >I'm a little unclear as to how tightly typed the type O variables
> are.
> > >If I declare a type O variable as class Widget, must I instatiate an
> > >object of type Widget to stick in there?  Can I use a subclass of
> > >Widget?  Can I use a class that's NOT a subclass, provided the method
> I
> > >later invoke has the same signature?
> > >
> > >I can do this with a factory method.  I'd have to instatiate the
> > >factory, and then pass the class name into the factory as a parameter
> to
> > >instantiate the actual object (or have a delegate method in the
> factory
> > >that emulates the desired method, only taking a class name as well).
> It
> > >would be a little easier if I could do it in the RPG, is all.
> >
> > Joe, maybe I'm stating the obvious here, and you've already looked
> into
> > this, but if not, it might be worth a try. I believe what you need is
> a
> > custom class loader. You can write them yourself if you study how Java
> > does it. This could be a static class and loader method, so that when
> you
> > called it with the class.method variable name it would not have to be
> > instantiated each time. You might even be able to do some of this in
> RPG,
> > but I'm not at all sure about that. But I have seen and heard of
> people
> > writing stranger class loaders than that -)! Also, as to your last
> point,
> > can't you define interfaces for the classes and methods you're
> interested
> > in ant invoke them via the interface method? By doing this you should
> be
> > able to slip in almost anything as long as the signature matches.
> >
> >
> > _________________________________________________________________
> > Jeff Furgal / MIMIX User Interface Product Architect / Lakeview
> Technology
> >
> > furgalj@xxxxxxxxxxxxxxxx / 630-282-8360
> >
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