This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
So you have an Android app that sends JSON via HTTP, and now you're looking for servlet code that retrieve sit from the HTTP request? Does HttpServletRequest.getParameter not do what you need done? If not, what else are you looking for, exactly?