When I was studying computer science at TU-Darmstadt there was this assignment to implement an http-server that proxies requests and caches responses (maybe in 2003 or 2004). In the same year I separated the http-parts and turned them into a simple http-server with no caching functionality. Over a decade later I now put this to github (after having mevenized it).

Build it with mvn clean install

Unzip the zip-archive found in target/http-server-*-dist.zip and unpack it to a destination of your choice. In that directory run it with

java -jar http-server-*.jar 8080

You'll find a tiny interactive console:

Will try to listen on port 8080
HTTP/1.x Server

Commands:
quit - gracefully quits the server.
help - displays this text.
gc - run garbage-collector
status - status info
?>

Then you might want to visit http://localhost:8080/index.html or whatever you put in the htdocs-directory.