Re: Packages and Reflection in an Applet

From:

=?ISO-8859-1?Q?Arne_Vajh=F8j?= <arne@vajhoej.dk>

Newsgroups:

comp.lang.java.programmer

Date:

Sat, 05 May 2012 17:30:50 -0400

Message-ID:

<4fa59c0e$0$285$14726298@news.sunsite.dk>

On 5/5/2012 1:25 AM, Richard Maher wrote:

I have an unsigned Applet that needs to obtain a Username/Password from the
user (via generic dialog boxes outside of the web-page) and optionally, on
successful login, display some "welcome" info from the server. To that end,
I have come up with a rudimentary AWT interface that pops-up a couple of
modal dialogue boxes. (There is also a "status" window that has bytes
received/sent etc).

Why not use Swing instead of AWT?

Or maybe even do it the Java 8 way with JavaFX?

So, I have the default, fallback, rough-as-guts option for obtaining user
credentials but would like to allow the consumers of my Applet to override
the default and supply their own much slicker +/- localized UI. So I have
the simple interface below that each prospective UI class must implement but
I don't know what part packages/protection play in this scenario as well as
reflection. If there are any people here with direct experience of the
following conditions/questions I would be very grateful for their advice: -

1) Can a class loaded via Reflection (eg: myInter localGUI =
(myInter)(class.forName("appletParameter").newInstance())) be in the same
Package, and enjoy the benefits/protection of same, as the caller? Ideally
here, the methods/variables/properties of the newly loaded class (albeit
under the restriction of being loaded from the same codebase) being package
private and not public? Again ideally, I do not want the methods in this GUI
to be accessible from JavaScript but obviously accessible from my applet.

The loaded class can certainly be in the same package as the caller.

2) I'd expect the "tier3Client" implementing class (and any additional
classes) to be supplied in a separate archive/JAR file and this will be
located via the "archive=a,b,c" specifier (with "codebase_lookup" set to
false). My "understanding" is that class.forName() will use the same
classloader as the Applet and therefore I'm hoping that it will happily
search through all specified JAR files looking for the requested class?

If you do not specify a classloader in the forName call (there is an
overload for that), then you will get the current classes classloader.

3) Are there any other restrictions/requirements or wil this just not work?

Will their jar and your jar be loaded from the same location?

Arne