Jetty 6: How to remove a Servlet?

Question

I need to programmatically add and remove a servlet on a Jetty 6 server. While it is almost straighforward to add I cannot find an effective way to remove. For my purposes it is important to add and remove a servlet because it is associated to a dynamic compontent architecture. I need to add a new service when I add a component and I need to remove the service when I remove the component.

To add a servlet I used this pattern:

Server server = new Server(8080);

class MyServlet extends HttpServlet
{
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException
    {

        resp.getOutputStream().write("Hello World!".getBytes());
    }
}


...


public void addServlet(HttpServlet s, String path)
{
    Context root = new Context(server,"/",Context.SESSIONS);
    root.addServlet(new ServletHolder(new MyServlet()), "/test/*");
    root.getServletHandler().
}
public void removeServlet(HttpServlet s, String path)
{
    //What I have to put here ? There is no removeServlet like methods in server/Context/ServletHolder
}

Why removing a servlet is not so obvious? Can you explain me the motivations ?

score 1 · Answer 1 · answered Mar 09 '12 at 20:21

first off I would recommend updating to jetty 7 or 8 if its possible, jetty 6 is quite old at this point and is lacking the last couple years of development that are present in 7 and 8. heck, jetty 9 is being actively worked on now.

second I wouldn't look at this on the servlet level but the handler level, working with the server to add and remove handlers, which can be either static resource type handlers or full fledged servlet context handlers, or even webapp context handlers.

as to why the servlet context handlers do not have remove servlet type operations, its really not a part of the servlet spec to remove active servlets at that level, fits more at the war deploy/undeploy level. feel free to open an issue on it though, I did experiment with adding and removing at servlet context handler level and you can remove them but it seems to be problematic then adding more afterwards, so I suspect removing the context itself and adding a new one would be your best bet at this point.

For project constraints I cannot move to jetty 7 or 8 ... Thanks anyway. — alexroat, Mar 20 '12 at 13:22
At the begining in fact I used handlers, anyway, in order to provide cross compatibility with existing solutions I need to move to standard java servlets. — alexroat, Mar 20 '12 at 13:23

score 1 · Answer 2 · edited May 23 '17 at 12:05

1

Here's instructions for doing it on Jetty 7.

Jetty : Dynamically removing the registered servlet

It should be pretty straight forward to port that code to Jetty 6.

edited May 23 '17 at 12:05

Community

1
1

answered Mar 10 '12 at 10:54

Tim

6,406
22
34

Thanks, I've used the same method adjusted for Jetty 6 – alexroat Mar 20 '12 at 13:24

alexroat · Answer 3 · 2012-03-20T13:24:52.593

This solution seems to be working:

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.mortbay.jetty.Server;
import org.mortbay.jetty.handler.ContextHandler;
import org.mortbay.jetty.handler.ContextHandlerCollection;
import org.mortbay.jetty.handler.ResourceHandler;
import org.mortbay.jetty.servlet.Context;
import org.mortbay.jetty.servlet.ServletHandler;
import org.mortbay.jetty.servlet.ServletHolder;
import org.mortbay.jetty.servlet.ServletMapping;

public class MyServer extends Server
{


    ServletHandler sh = new ServletHandler();


    public MyServer()
    {
        super(9090);
        setHandler(sh);
        test();
    }


    class MyServlet extends HttpServlet
    {
        /**
         * 
         */
        private static final long serialVersionUID = 1L;

        @Override
        protected void doGet(HttpServletRequest req, HttpServletResponse resp)
                throws ServletException, IOException
        {
            resp.getWriter().println("CIAO!");
        }
    }

    void test()
    {



        MyServlet ms = new MyServlet();

        addServlet(ms, "/ciao/*");

        //removeServlet(ms);//uncomment this ilne in order to remove the servlet right after the deploy

    }

    public void addServlet(HttpServlet s, String path)
    {
        sh.addServletWithMapping(new ServletHolder(s), path);


        for (ServletHolder so : sh.getServlets())
            try
            {
                System.out.println((so.getServlet() == s));
            } catch (ServletException e)
            {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

    }


    public void removeServlet(HttpServlet s)
    {
        try
        {
            HashSet<String> names = new HashSet<String>();
            for (ServletHolder so : sh.getServlets())
                if (so.getServlet() == s)
                    names.add(so.getName());

            HashSet<ServletMapping> sms = new HashSet<ServletMapping>();
            for (ServletMapping sm : sh.getServletMappings())
            {
                if (!names.contains(sm.getServletName()))
                    sms.add(sm);
            }

            sh.setServletMappings(sms.toArray(new ServletMapping[] {}));
        } catch (ServletException e)
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

}

Jetty 6: How to remove a Servlet?

3 Answers3