An example that shows how to dynamically change servlets

DynamicServletLauncher.java

package io.activej.launchers.http;

import io.activej.http.AsyncServlet;
import io.activej.http.HttpResponse;
import io.activej.http.RoutingServlet;
import io.activej.inject.annotation.Named;
import io.activej.inject.annotation.Provides;

import java.util.concurrent.ThreadLocalRandom;

public final class DynamicServletLauncher extends HttpServerLauncher {

	@Provides
	AsyncServlet mainServlet(@Named("First") AsyncServlet firstServlet, @Named("Second") AsyncServlet secondServlet) {
		return RoutingServlet.create()
				.map("/*", request -> HttpResponse.ok200()
						.withHtml("<h2><a href='/dynamic'>Go to dynamic servlet</a></h2>"))
				.map("/dynamic/*", request -> {
					if (ThreadLocalRandom.current().nextBoolean()) {
						return firstServlet.serve(request);
					} else {
						return secondServlet.serve(request);
					}
				});
	}

	@Provides
	@Named("First")
	AsyncServlet firstServlet() {
		return request -> HttpResponse.ok200().withHtml("<h1>This page is served by first servlet</h1>");
	}

	@Provides
	@Named("Second")
	AsyncServlet secondServlet() {
		return request -> HttpResponse.ok200().withHtml("<h1>This page is served by second servlet</h1>");
	}

	public static void main(String[] args) throws Exception {
		new DynamicServletLauncher().launch(args);
	}
}