Undertow + servlet trial http://undertow.io/documentation/servlet/deployment.html

build.gradle

apply plugin: 'idea'
apply plugin: 'java'

group = 'me.masahito'
version = "0.0.1"
sourceCompatibility = targetCompatibility = 1.8
repositories.mavenCentral()

dependencies {
  compile 'io.undertow:undertow-core:1.1.1.Final'
  compile 'io.undertow:undertow-servlet:1.1.1.Final'
  compile "javax.servlet:javax.servlet-api:3.1.0"
}g

Main.java

package me.masahito;

import io.undertow.Handlers;
import io.undertow.Undertow;
import io.undertow.server.handlers.PathHandler;
import io.undertow.servlet.Servlets;
import io.undertow.servlet.api.DeploymentInfo;
import io.undertow.servlet.api.DeploymentManager;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

/**
 * Created by masahito on 15/01/07.
 */
public class Main {
    public static void main(String[] args) throws Exception {
        final DeploymentInfo servletBuilder = Servlets.deployment()
                .setClassLoader(Main.class.getClassLoader())
                .setContextPath("/myapp")
                .setDeploymentName("test.war")
                .addServlets(
                        Servlets.servlet("HelloServlet", HelloServlet.class)
                                .addMapping("/*"));
        final DeploymentManager manager = Servlets.defaultContainer().addDeployment(servletBuilder);
        manager.deploy();
        final PathHandler path = Handlers.path(Handlers.redirect("/myapp"))
                .addPrefixPath("/myapp", manager.start());

        final Undertow server = Undertow.builder()
                .addHttpListener(8080, "localhost")
                .setHandler(path)
                .build();
        server.start();
    }
    public static class HelloServlet extends HttpServlet {

        private static final long serialVersionUID = -6154475799000019575L;

        private static final String greeting = "Hello World";

        protected void doGet(HttpServletRequest request,
                             HttpServletResponse response) throws ServletException,
                IOException {

            response.setContentType("text/html");
            response.setStatus(HttpServletResponse.SC_OK);
            response.getWriter().println(greeting);
        }

    }


}