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Class JSR356WebsocketInitializer

  • All Implemented Interfaces:

    EventListener, javax.servlet.ServletContextListener

    @WebListener
public class JSR356WebsocketInitializer
extends Object
implements javax.servlet.ServletContextListener

    Initializer class for JSR 356 websockets.

    Websocket specification says that initialization of websocket end points should be done in the servlet context initialization phase. Some servers implement this strictly so that end points cannot be registered after the context initialization phase.

    Note that WebListener is Servlet 3.0 API so this will not be run for older servers (unless added to web.xml), but these servers do not support JSR 356 websockets either.

    Since:

    7.5.0

    Author:

    Vaadin Ltd

    • Nested Class Summary

      Nested Classes
      Modifier and Type Class Description
      static class  JSR356WebsocketInitializer.FakeServletConfig

      "ServletConfig" which only provides information from a ServletRegistration and its ServletContext.

    • Method Summary

      All Methods
      Modifier and Type Method Description
      void contextDestroyed​(javax.servlet.ServletContextEvent sce)  
      void contextInitialized​(javax.servlet.ServletContextEvent sce)  
      static String getAttributeName​(String servletName)

      Returns the name of the attribute in the servlet context where the pre-initialized Atmosphere object is stored.
      void init​(javax.servlet.ServletContext servletContext)

      Initializes Atmosphere for use with Vaadin servlets found in the given context.
      static void initAtmosphereForVaadinServlet​(javax.servlet.ServletRegistration servletRegistration, javax.servlet.ServletContext servletContext)

      Initializes Atmosphere for use with the given Vaadin servlet
      static boolean isAtmosphereAvailable()

      Checks if Atmosphere is available on the classpath.
      protected boolean isVaadinServlet​(javax.servlet.ServletRegistration servletRegistration, javax.servlet.ServletContext servletContext)

      Tries to determine if the given servlet registration refers to a Vaadin servlet.

    • Constructor Detail

      • JSR356WebsocketInitializer

        public JSR356WebsocketInitializer()

    • Method Detail

      • contextInitialized

        public void contextInitialized​(javax.servlet.ServletContextEvent sce)

        Specified by:

        contextInitialized in interface javax.servlet.ServletContextListener

      • init

        public void init​(javax.servlet.ServletContext servletContext)

        Initializes Atmosphere for use with Vaadin servlets found in the given context.

        For JSR 356 websockets to work properly, the initialization must be done in the servlet context initialization phase.

        Parameters:

        servletContext - The servlet context

      • initAtmosphereForVaadinServlet

        public static void initAtmosphereForVaadinServlet​(javax.servlet.ServletRegistration servletRegistration,
                                                  javax.servlet.ServletContext servletContext)

        Initializes Atmosphere for use with the given Vaadin servlet

        For JSR 356 websockets to work properly, the initialization must be done in the servlet context initialization phase.

        Parameters:

        servletRegistration - The servlet registration info for the servlet

        servletContext -

      • getAttributeName

        public static String getAttributeName​(String servletName)

        Returns the name of the attribute in the servlet context where the pre-initialized Atmosphere object is stored.

        Parameters:

        servletName - The name of the servlet

        Returns:

        The attribute name which contains the initialized Atmosphere object

      • isVaadinServlet

        protected boolean isVaadinServlet​(javax.servlet.ServletRegistration servletRegistration,
                                  javax.servlet.ServletContext servletContext)

        Tries to determine if the given servlet registration refers to a Vaadin servlet.

        Parameters:

        servletRegistration - The servlet registration info for the servlet

        Returns:

        false if the servlet is definitely not a Vaadin servlet, true otherwise

      • contextDestroyed

        public void contextDestroyed​(javax.servlet.ServletContextEvent sce)

        Specified by:

        contextDestroyed in interface javax.servlet.ServletContextListener

      • isAtmosphereAvailable

        public static boolean isAtmosphereAvailable()

        Checks if Atmosphere is available on the classpath.

        Returns:

        true if Atmosphere is available, false otherwise