This library is an Android networking abstraction library consisting of a combination of Volley, OkHttp, and Jackson, with a little glue to stick it all together. It's a great place to start if you need to execute requests, especially thos which return JSON.
funzhang/Volley-OkHttp-Android
This is a clone of Volley, with the relevant changes made to make it work with Square's OkHttp library. It also has Jackson integrated to provide a convenient object model.
Java