public static void main(String[] args) throws UnknownHostException {
    MongoClient client = new MongoClient(new ServerAddress("localhost", 27017));
    final DB db = client.getDB("course");

    Spark.get(
        new Route("/") {
          @Override
          public Object handle(Request request, Response response) {
            DBCollection users = db.getCollection("user");
            DBObject user = users.findOne();
            StringWriter writer = new StringWriter();
            Configuration configuration = new Configuration();
            configuration.setClassForTemplateLoading(
                HelloWorldMongoDBSparkFreemarkerStyle.class, "/");

            try {
              Template template = configuration.getTemplate("hello.ftl");
              template.process(user, writer);
            } catch (Exception e) {
              halt(100);
              e.printStackTrace();
            }

            return writer;
          }
        });
  }