protocol buffers in android

I am developing an Android app in which I am using JSON, now for performance I have to test by using protocol buffers. If som开发者_StackOverflow中文版eone knows simple and easy implementation of this, please let me know. I have been following this tutorial to implement it. The problem I am getting is in class generated by the protocol buffer compiler I have to no idea why I am getting error on importing

 com.google.protobuf.ExtensionRegistry registry
 com.google.protobuf.GeneratedMessage

I have tried to add the protcol buffer jar from the "add jar from external resource " but it hasn't worked . Any suggestions?