This time it is a plain web app use only servlet :)
The whole folder is a maven project, refernces pom.xml. Use mvn package order you can make it into a war.
I deleted the target folder and put the war file just under the project folder. Deploy it to server you can get a response like "hello world" at path "/test/hello".
A junit test case was added, but I decided to keep the old python file.
Sept 5 edit: Adjust the project under the instruction.
author: zwqStella