If you want to see how few lines of code are required to run a server on your phone/tablet, take a look at the sample that comes with DroidScript
HTTP_Server
Run a web server on your device
If you use the Wi-fi IDE from a Chromebook or PC to write code on your phone, that is served by app.CreateWebServer()
As far as I know that's what it wants but I'm not an expert on Jetty.