Re: "Proper" way to Access Java from javascript

On Dec 2, 1:55 pm, Brett Zamir <[email protected]> wrote:
> sam keen wrote:
> > liveconnect:
> >  - is this true "LiveConnect may be removed from Mozilla 2.0 according
> > to this post by Josh."
>
> I'd sure like an answer on this one too....>  - for statements like var red = new Packages.HelloWorld();   where do
> > you place your jar file so it can be found?
>
> I believe that Packages will not allow you access to your own packages
> (I learned this the hard way). Try using URLClassLoader. Seehttp://developer.mozilla.org/en/docs/Talk:Java_in_Firefox_Extensionsfor
> examples of usage with LiveConnect... If the files are local you can use
> the file:/// protocol... I needed to put the loader (called via
> LiveConnect) in global scope for my own extension that uses this, so
> that it would not attempt to load multiple times and thus cause errors
> (I guess with DLL files)...
>
> And for my case of finding my own extension directory to find the jar
> file, I did, with the bold portion at the end being my own extension
> identifier:
>
>     var path =
> Components.classes["@mozilla.org/file/directory_service;1"].getService(
> Components.interfaces.nsIProperties).get("ProfD",
> Components.interfaces.nsIFile).path; // Get path to user profile folder
>     var extpath = path+'/extensions/*[email protected]/'*;
>
> One problem with this though is that "Classes loaded by a URLClassLoader
> have whatever permissions are granted to their java.security.CodeSource
> by the system java.security.Policy" (Java in a Nutshell, p. 582). You
> need to either have permission granted to the jars in a user home
> .java.policy file, or use the trick (a good trick) in the Java Firefox
> extension to get permissions granted for your app. I'm doing the former
> now during testing, but hope to use the Java Firefox extension (XPCOM)
> approach in the future (which also gives the benefit of getting one
> single Java object for all windows)...
>
> One other tip: the try-catch blocks in Javascript do not work for me--I
> needed to perform them within Java (I built wrapper methods to make this
> expandable).
>
> best wishes,
> Brett

thanks for the info Brett,

I did figure out java.net.URLClassLoader (using a complete file path).
I'll try your code out for getting the extension path (thanks for the
snippet)
And yes I did hit the security policy wall.  All my java code works
until it gets to interacting with the Runtime object.
Thanks for the .java.policy reference,  I'll see if I can get that
working and then move onto the Java Firefox ext hack as you are.

regards,
Sam