Calling Java code in custom JARs from Javascript

This is perhaps the easiest way to call Java code in your own custom JAR files from Javascript code in your extension:

   var cl = new Packages.java.net.URLClassLoader(

       [

           new Packages.java.net.URL(

               'http://foo.net/bar.jar')

       ]

   );



   var aClass = Packages.java.lang.Class.forName("HelloWorld", true, cl);

   var aStaticMethod = aClass.getMethod("getGreeting", []);

   var greeting = aStaticMethod.invoke(null, []);

   alert(greeting);

If you would rather include your JAR file in your extension package, you might need to map a chrome URL to a file path, which can be done using jslib.

Please beware that the code above might freeze the browser for a short while as the JVM loads.