Given that URLStreamHandlerFactory is an interface and thus contains no
behavioural code, this sounds like a really bad idea.

   But if you really wanted to do this, I suppose you could go into your
JRE directory and mess around with the JAR/ZIP files to replace th existing
stuff there with your new class file.

   - Oliver

The two obvious choices are:

Use a Java Agent to call URL.setURLStreamHandlerFactory, but not
actually do any instrumentation. I've got an example of doing something
similar with EventQueue.push.

http://jroller.com/page/tackline?entry=detecting_invokeandwait_abuse

The alternative is to set -Djava.protocol.handler.pkgs=mypackage, then
instead of using URLStreamHandlerFactory provide URLStreamHandler
classes with no-arg constructors and names of the form
mypackage.protocol.Handler. See the source code to URL...

Tom Hawtin