App Engine Hello World

App Engine Hello World

September 19, 2020

example java server google-cloud app-engine

This is a barebones example webapp using Google Cloud.

View the code for this project here.

Download the code as a .zip from DownGit here.


pom.xml is a Maven POM file that defines the project.

<project xmlns=""


    <!-- App Engine currently supports Java 11 -->

    <!-- Project-specific properties -->

    <!-- Java Servlets API -->

    <!-- Jetty -->

      <!-- Copy static resources like html files into the output jar file. -->

      <!-- Package everything into a single executable jar file. -->
                <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">

      <!-- App Engine plugin for deploying to the live site. -->


app.yaml is a config file that sets up App Engine. This hello world project only uses a single property that sets the runtime to Java 11.

runtime: java11 is the main class that sets up the server.

package io.happycoding;

import org.eclipse.jetty.annotations.AnnotationConfiguration;
import org.eclipse.jetty.server.Handler;
import org.eclipse.jetty.server.handler.DefaultHandler;
import org.eclipse.jetty.server.Server;
import org.eclipse.jetty.servlet.DefaultServlet;
import org.eclipse.jetty.webapp.Configuration;
import org.eclipse.jetty.webapp.WebAppContext;
import org.eclipse.jetty.webapp.WebInfConfiguration;

 * Starts up the server, including a DefaultServlet that handles static files,
 * and any servlet classes annotated with the @WebServlet annotation.
public class ServerMain {

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

    // Create a server that listens on port 8080.
    Server server = new Server(8080);
    WebAppContext webAppContext = new WebAppContext();

    // Load static content from inside the jar file.
    URL webAppDir =

    // Enable annotations so the server sees classes annotated with @WebServlet.
    webAppContext.setConfigurations(new Configuration[]{
      new AnnotationConfiguration(),
      new WebInfConfiguration(),

    // Look for annotations in the classes directory (dev server) and in the
    // jar file (live server)

    // Handle static resources, e.g. html files.
    webAppContext.addServlet(DefaultServlet.class, "/");

    // Start the server! 🚀
    System.out.println("Server started!");

    // Keep the main thread alive while the server is running.
} is a Java servlet that returns some HTML content.

package io.happycoding.servlets;


import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class HelloWorldServlet extends HttpServlet {

  public void doGet(HttpServletRequest request, HttpServletResponse response)
      throws IOException {
    response.getOutputStream().println("<h1>Hello world!</h1>");


index.html is an HTML file that shows static content.

<!DOCTYPE html>
    <meta charset="UTF-8">
    <title>Google Cloud Hello World</title>
    <h1>Google Cloud Hello World</h1>
    <p>This is a sample HTML file. Click <a href="/hello">here</a> to see content served from a servlet.</p>
    <p>Learn more at <a href=""></a>.</p>

You can run this locally by executing this command:

mvn package exec:java

Then visit http://localhost:8080 in your web browser, and you should see this:

app engine hello world

Learn more in these tutorials:

App Engine Examples


Happy Coding is a community of folks just like you learning about coding.
Do you have a comment or question? Post it here!

Comments are powered by the Happy Coding forum. This page has a corresponding forum post, and replies to that post show up as comments here. Click the button above to go to the forum to post a comment!