Guice can't create async servlet

From swapii on August 30, 2011 07:39:51

I’ve connect Guice to my project, write web.xml and everything gone right until I wan’t to realize async servlet. I using Tomcat 7.0.20 and Guice 3.0. Servlets spec version is 3.0.

Test Comet servlet:

@Singleton @WebServlet(name = “comet”, urlPatterns = {“/comet”}, asyncSupported = true) public class CometServlet extends HttpServlet {

        private class TestThread implements Runnable {

                private AsyncContext context;

                public TestThread(AsyncContext ctx) {                         context = ctx;                 }

                @Override                 public void run() {                         try {                                 Thread.sleep(5000);                                 context.getResponse().getWriter().write(“TEST!”);                         } catch (InterruptedException e) {                                 e.printStackTrace();                         } catch (IOException e) {                                 e.printStackTrace();                         }                 }         }

        @Override         protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {                 AsyncContext ctx = req.startAsync(req, resp);                 new Thread(new TestThread(ctx)).start();         }          }

Servlet created, it placed at “/comet” path, but async not working and error was printed:

HTTP Status 500

java.lang.IllegalStateException: Not supported.         org.apache.catalina.connector.Request.startAsync(Request.java:1638)         org.apache.catalina.connector.RequestFacade.startAsync(RequestFacade.java:1031)         javax.servlet.ServletRequestWrapper.startAsync(ServletRequestWrapper.java:379)         javax.servlet.ServletRequestWrapper.startAsync(ServletRequestWrapper.java:379)         ru.unimobi.cinema.server.server.servlets.CometServlet.service(CometServlet.java:46)         javax.servlet.http.HttpServlet.service(HttpServlet.java:722)         com.google.inject.servlet.ServletDefinition.doService(ServletDefinition.java:216)         com.google.inject.servlet.ServletDefinition.service(ServletDefinition.java:141)         com.google.inject.servlet.ManagedServletPipeline.service(ManagedServletPipeline.java:93)         com.google.inject.servlet.FilterChainInvocation.doFilter(FilterChainInvocation.java:63)         com.google.inject.servlet.FilterDefinition.doFilter(FilterDefinition.java:134)         com.google.inject.servlet.FilterChainInvocation.doFilter(FilterChainInvocation.java:59)         com.google.inject.servlet.ManagedFilterPipeline.dispatch(ManagedFilterPipeline.java:122)         com.google.inject.servlet.GuiceFilter.doFilter(GuiceFilter.java:110)

I think this is bug, because I write web.xml directly without Guice and it working as expected.

_Original issue: http://code.google.com/p/google-guice/issues/detail?id=650_

[cstamas]

I think this issue, at least it’s title is wrong: “Guice can’t create async servlet” is not true.

Guice can create async servlet (just don’t forget to set <async-supported>true</async-supported> on guice filter in web.xml).

Just FTR, as I got puzzled by this opened issue, while creating a POC that basically proved the opposite of this issue.

[atais]

There is yet another way to register the async servlet in guice context. It works with constructor injection and no annotations.

// initialize all your beans, with servlets
val i = Guice.createInjector(new AbstractModule(){...})

// Guice context listener just needs to register the beans to servlet context
class AppServletContextListener extends GuiceServletContextListener {
  def getInjector: Injector = i.createChildInjector(new ServletRegistrator(i))
}

class ServletRegistration(i: Injector) extends ServletModule with ScalaServletModule {
  override def configureServlets(): Unit = {
    serve("/sync-home").`with`(classOf[SyncHomeServlet])

    // async
    val registration = getServletContext.addServlet(classOf[AsyncHomeServlet].getSimpleName, classOf[AsyncHomeServlet])
    registration.setAsyncSupported(true)
    registration.addMapping("/async-home")
  }
}