问题
I want to be able to connect to various back-ends by changing a custom header of my HTTP requests. Therefore I want that my request is served with a controller instance that is specific to the selected back-end. The controllers that serve the requests are created using Guice and have many dependencies. I want to cache these controller instances. So for each (SomeController.class, backend) pair there would be a cached instance.
How to implement such a Guice scope? I am using Play Framework 2.1.
来源：https://stackoverflow.com/questions/15556802/how-to-implement-a-new-guice-scope-that-caches-and-return-named-instances