Java: Simple HTTP Server application that responds in JSON

Question

I want to create a very simple HTTP server application in Java.

For example, if I run the server on localhost in port 8080, and I make

Answer 1

Run main to start the server on port 8080

public class Main {
    public static void main(String[] args) throws LifecycleException {
        Tomcat tomcat = new Tomcat();
        Context context = tomcat.addContext("", null);

        Tomcat.addServlet(context, "func1", new HttpServlet() {
            protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException {
                Object response = func1(req.getParameter("param1"), req.getParameter("param2"));

                ObjectMapper mapper = new ObjectMapper();
                mapper.writeValue(resp.getWriter(), response);
            }
        });
        context.addServletMappingDecoded("/func1", "func1");

        tomcat.start();
        tomcat.getServer().await();
    }

    private static String[] func1(String p1, String p2) {
        return new String[] { "hello world", p1, p2 };
    }
}

Gradle dependencies:

dependencies {
    compile group: 'org.apache.tomcat.embed', name: 'tomcat-embed-core', version: '8.5.28' // doesn't work with tomcat 9
    compile group: 'com.fasterxml.jackson.core', name: 'jackson-databind', version: '2.9.4'
}