An example of dynamic routing based on mime type

MimeTypeRoutingExample.java

package io.activej.launchers.http;

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

public final class MimeTypeRoutingExample extends HttpServerLauncher {

	private static final String IMAGE_TYPE_PREFIX = "image/";
	private static final String TEXT_TYPE_PREFIX = "text/";

	@Provides
	AsyncServlet mainServlet(@Named("Image") AsyncServlet imageServlet, @Named("Text") AsyncServlet textServlet) {
		return RoutingServlet.create()
				.map("/*", request -> {
					String contentType = request.getHeader(HttpHeaders.CONTENT_TYPE);
					if (contentType == null) {
						return HttpResponse.ofCode(400).withPlainText("Content type is missing");
					}
					if (isImageType(contentType)) {
						return imageServlet.serve(request);
					} else if (isTextType(contentType)) {
						return textServlet.serve(request);
					} else {
						return HttpResponse.ofCode(400).withPlainText("Unsupported content type");
					}
				});
	}

	@Provides
	@Named("Image")
	AsyncServlet imageServlet() {
		return request -> HttpResponse.ok200().withHtml("<h1>This servlet handles images</h1>");
	}

	@Provides
	@Named("Text")
	AsyncServlet textServlet() {
		return request -> HttpResponse.ok200().withHtml("<h1>This servlet handles text data</h1>");
	}

	private static boolean isTextType(String mime) {
		return mime.startsWith(TEXT_TYPE_PREFIX) && mime.length() > TEXT_TYPE_PREFIX.length();
	}

	private static boolean isImageType(String mime) {
		return mime.startsWith(IMAGE_TYPE_PREFIX) && mime.length() > IMAGE_TYPE_PREFIX.length();
	}

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