Re: How to inform web site visitor that Sun Java is required?

From:
"Andrew Thompson" <u32984@uwe>
Newsgroups:
comp.lang.java.programmer
Date:
Fri, 22 Jun 2007 09:27:56 GMT
Message-ID:
<74129d100b077@uwe>
Joshua Cranmer wrote:
...

There is no HTML you could write, ..


'Sure there is'. Or rather, there is some HTML with a
redirect meta tag (to "nojava.html"), set for a number
of seconds, combined with a small Java applet that
calls showDocument("sunjava.html"); after the
appropriate checks (like shown in the JS below -
but done in the applet).

..but there is some JavaScript:

function checkSunJava() {
   if (java.lang.System.getProperty("java.vendor").indexOf("Sun") != 0)
       alert('This page requires Sun Java.');
}

Alternatively, if your requirement is merely that the person needs Java,
this should (untested) work:

<applet ...> <!-- Or object or whatever -->
This page requires Java to work properly.
</applet>


Unfortunately not. The 'no java' section of the applet
element is only intended for browsers that have never
seen or heard of the <applet> element. There are
other browsers that had Java installed at some stage,
but it is now *disabled* thru browser config. settings.

But that is not the half of it..

I have applet elements that include *both* the alt
attribute and the 'no java' section. There are
browsers (or at least, installations of IE) that
will display the result as a 'big grey square' on
the web page. I expect it is because of some over
zealous combination of security settings (e.g.
disabled in IE's config., as well as running Norton
on 'maximum paranoia' settings) but never got to
investigate in detail.

Lew also made some good points about web start.

Ultimately though, I am not convinced this applet
requires 'Sun' Java. Why did you say that? Does
it use Swing? What is the minimum Java version
it can run in?

--
Andrew Thompson
http://www.athompson.info/andrew/

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