How do I add HttpServer features to Java application, must work for Oracle and Open JDK

Question

I have an application, currently can run as a Gui Application or command line only. I want to add support so that its runs a server, and can be controlled via a different computer via web browser.

So it will run continously on port, and I want user to connect to that port in browser and see a summary page, then be able to initiate requests via http get requests.

Its need to work with OpenJdk not just Oracle Java so I guess that stops use of com.sun.httpserver.

This is an improvement to an existing product it cannot be reengineered to run as a servlet within a Servlet Engine such as Jetty or Tomcat, in fact most users will continue to use it in Gui or cmd line mode.

I don't want to reinvent the wheel so I don't want to try add this basic http support from scratch.

I am using Java 8

Can some suggest an approach.

Answer 1

Try Spark Java.

Add maven pom dpendency:

<dependency>
    <groupId>com.sparkjava</groupId>
    <artifactId>spark-core</artifactId>
    <version>2.6.0</version>
</dependency>

and then you will be able to start simple web server. The example shows only get method URI, but all HTTP methods are available.

import static spark.Spark.*;

public class HelloWorld {
    public static void main(String[] args) {
        get("/hello", (req, res) -> "Hello World");
    }
}

Check it working:

http://localhost:4567/hello

---

There are, of course other solutions, like NanoHttpd — the most basic implementation of HTTP server I had ever seen. Usually used in android apps.