Hello.java

import java.io.*;
import java.net.URL;
import java.util.*;
import java.util.regex.*;

import javax.servlet.http.*;
import javax.servlet.http.HttpServletResponse;

import org.eclipse.jetty.server.Request;
import org.eclipse.jetty.server.Server;
import org.eclipse.jetty.server.handler.AbstractHandler;

import org.json.JSONObject;

public class Main {
    public static void main(String[] args) throws Exception {

        Server server = new Server(8080);
        server.setHandler(new AbstractHandler(){
            @Override
            public void handle(String target, 
                                Request baseRequest, 
                                HttpServletRequest request, 
                                HttpServletResponse response) throws IOException {
                
                baseRequest.setHandled(true);
                PrintWriter writer = response.getWriter();

                Matcher matcher = Pattern.compile("/hello/(\\d)").matcher(target);
                if (matcher.matches()) {
                    String id = matcher.group(1);
                    InputStream source = new URL("http://jsonplaceholder.typicode.com/users/" + id).openStream();
                    try ( Scanner s = new Scanner(source) ) {
                        JSONObject jsonObject = new JSONObject(s.useDelimiter("\\A").hasNext() ? s.next() : "");
                        writer.printf("The name for id %s is %s", id, jsonObject.get("name"));
                    }
                } else {
                    response.setStatus(HttpServletResponse.SC_NOT_FOUND);
                    writer.println("Usage: /hello/id where id = single digit");
                }
            }
        });
        server.start();
        server.join();
    }
}