Implementing Gmail API in JavaEE application

I have to make a web Application using Gmail API to read users mail and sort them according to the frequency count. I went through http://ift.tt/1lUKQJu but I cannot found anything related to JavaEE application, there are tuts for command line application and for all other languages. What i want is place to get info about the same. It's almost 5hrs and i am still stucked.I have already created the project in developer console and generated the Client ID and downloaded the JSON file but don't know what to do next can someone provide me the link to proceed further.