JPack v1.0 was released on February 13, 1997.
JPack v1.0 was released on February 13, 1997.
This document is divided into the following sections:
JPack is a little DOS application I whipped up to automate the process of building these archive files, and to help create the APPLET tags to support them. Just give JPack a list of packages, and it will do the rest.
The JPack home page is currently located at:
JPACK archive_name package(s)"archive_name" will be used as the base name for creating the two archives. For example, passing "Animator" results in two files being created, animator.cab and animator.zip.
The package names are used by JPack to find the classes, and also to define the necessary structure inside the archives. Use "." to archive the class files in the current directory if you aren't using a package.
When you run JPack, it will create ZIP and CAB files containing the given classes. JPack will also output a template APPLET tag for loading an applet using these archives.
ZIP.EXE is a version of zip which supports long file names
and can be used from the command line. Pkzip 2.04g doesn't cut it,
since it doesn't support long file names. ZIP.EXE is
distributed as part of the InfoZip library. JPack has been tested with
ZIP version 2.0.1. The latest version of the InfoZip library can be
found at:
Let's say you've just finished an Applet called TinyMouse, consisting
of eight classes, none of which are in packages. Your directory might
be organized like this:
Your latest applet, Sneakers, is a masterpiece. Based on an old Apple
II game, it features double buffering, smooth scrolling, and lots of
heart pounding animated fun. The only problem is that the applet
turned out to be a real behemoth - thirty classes in three different
packages. Naturally, you want to pack all of these classes into an
archive to speed things up.
The Sneakers applet is organized into three packages (sneakers.game,
sneakers.sound, and highscore), and looks something like this:
JPack is a DOS application which automates the process of building
CAB/ZIP archives for Java applets.
2. Who are you?
My name is Adam Doppelt. I'm a Senior at Brown University, majoring
in Computer Science. I'll be graduating in May 1997, so my home
page and email might be moving. My home page is currently at:
3. Why did you write JPack?
Recently, I was trying to figure out how to create these archives.
It was a pain in the neck. I originally had a JPack batch file
to do it, but it wasn't smart enough. I decided to crack the old
Turbo C++ and write something better.
It only took a few minutes, but when it was done I figured other
people might get some use out of it. Also, it would be useful to
have a site which explained how the process worked and have
pointers to more information.
4. Why does JPack complain that it can't find ZIP.EXE or CABARC.EXE?
JPack doesn't actually create the archives itself. Instead, it uses
ZIP.EXE to create the ZIP archive and CABARC.EXE
to create the CAB archive. Yes, it's true - JPack is basically just
an intelligent batch file.
You need these two programs in order to use JPack. You can find
pointers to them at the JPack home page:
Pkzip 2.04g is a great program, but it doesn't support long file
names. That's why we need ZIP.EXE.
6. What does all that crazy JPack output mean?
You are seeing the output as JPack does its work. JPack first calls
CABARC.EXE, and then ZIP.EXE. If you look
carefully, you can actually spot the command lines used to call
those two applications. Maybe you don't need JPack after all, eh?
7. Why can't my browser find the ZIP or CAB archive?
Make sure that you've put the ZIP and CAB archives in the directory
specified as the CODEBASE parameter to your applet. Remember that
browsers interpret the string as a relative path, starting with the
location of the current web page.
8. What happens if a particular browser doesn't support either archive
format?
If a browser doesn't support either format, it will ignore both the
ARCHIVE and CABBASE parameters to the applet, and
attempt to load the applet in the usual manner. The "usual manner"
means looking for classes and packages in the CODEBASE
directory. See the examples above for more information.
9. How to I check to see what's in the archives?
To view the contents of a zip archive, type:
To view the contents of a cab archive, type:
10. You refer to Java "packages". What are they?
Java organizes classes into "packages", similar to a directory in a
file system. For example, "java.awt" contains all of Java's awt
classes. Java uses packages to organize classes logically (using
import/package statements) and also to arrange classes on disk. For
more information, check out the Java Package Tutorial:
3. ZIP.EXE and CABARC.EXE
JPack doesn't actually create the archives itself. Instead, it
requires two freely available applications, ZIP.EXE and
CABARC.EXE to create the archives. You must already have
these applications before you can use JPack. If JPack cannot find both
of these applications somewhere in your PATH, it will not work.4. Examples
TinyMouse c:\classes\
TinyMouse.class TinyApplet.class TinyCat.class
TinyHamster.class ...
You've just downloaded JPack (as well as ZIP.EXE and
CABARC.EXE) to package all eight classes into a single
archive, improving download speed immensely. Assuming
JPACK.EXE, ZIP.EXE and CABARC.EXE are all
in your path somewhere, you can create the archives by typing:
c:\>cd c:\classes\
c:\classes\>jpack mouse .
The "." tells JPack to archive just the classes in the
current directory. JPack will create two archives (mouse.cab
and mouse.zip) and spit out the following APPLET
template: java/tinymouse/ (TinyMouse directory)
index.html (TinyMouse home page)
classes/ (directory containing classes and archives)
mouse.cab (used by Internet Explorer)
mouse.zip (used by Netscape)
TinyMouse.class (used by all other browsers)
TinyApplet.class ...
...
In order to load this applet, you would have to copy the
APPLET template that JPack produced into
tinymouse/index.html, and modify it to read: c:\classes\
sneakers\
game\
Applet.class Meteor.class Player.class ...
sound\
Bang.class Bop.class GameOver.class ...
highscore\
NewHigh.class ShowScores.class Client.class ...
Having just installed JPack, ZIP.EXE, and CABARC.EXE
you pack up the files by typing: c:\>cd c:\classes\
c:\classes\>jpack sneakers sneakers.game sneakers.sound highscore
JPack will create two archives (sneakers.cab and
sneakers.zip) and spit out the following APPLET
template: java/sneakers/ (Sneakers directory)
index.html (Sneakers home page)
my_classes/ (directory containing classes and archives)
sneakers.cab (used by Internet Explorer)
sneakers.zip (used by Netscape)
sneakers/ (sneakers package, for other browsers)
game/ (sneakers.game package, for other browsers)
Applet.class
Meteor.class
...
sound/ (sneakers.sound package, for other browsers)
Bang.class
Bop.class
...
highscore/ (highscore package, for other browsers)
NewHigh.class
ShowScores.class
...
In order to load this applet, you would have to copy the
APPLET template that JPack produced into
java/sneakers/index.html, and modify it to read:5. FAQ
1. What does JPack do?
unzip -l file.zip
cabarc l file.cab
Back to The Old Stuff,
or maybe you want to mail Adam.