Getting error 503 after adding listener class in web.xml

Question

I am using Jetty server and I want to put one check at the time of server start. For that I have created one listener class and put its entry in web.xml as per following:

Listener Class:

public class LicenseCheck extends ContextLoaderListener
{
    private static final Logger log = Logger.getLogger(LicenseCheck.class);

    public LicenseCheck()
    {
        log.info("Checking license");
    }
}

Web.xml:

<?xml version="1.0" encoding="UTF-8"?>
<web-app id="WebApp_ID" version="2.4"
  xmlns="http://java.sun.com/xml/ns/j2ee"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">


  <!-- spring context listener -->
  <context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>
        classpath:applicationContext.xml
    </param-value>
  </context-param>


  <listener>
    <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
  </listener>

  <listener>
        <listener-class>com.license.LicenseCheck</listener-class>
    </listener>


   <!-- Index pages -->
   <welcome-file-list>
     <welcome-file>index.html</welcome-file>
   </welcome-file-list>

</web-app>

But after adding this, my application cannot start and its throwing following exception:

HTTP ERROR: 503

Problem accessing /. Reason:

      Service Unavailable 

Powered by Jetty://

If I remove the listener's entry from web.xml it works fine.

Please provide solution for this.

Answer 1

I Got the solutions from log:

Log says:

2014-04-03 18:50:41.969:WARN::Failed startup of context org.mortbay.jetty.webapp.WebAppContext@58afc4dd{/SpringMVCRest,D:\Workspace\SpringMVCRest\WebContent} java.lang.IllegalStateException: Cannot initialize context because there is already a root application context present - check whether you have multiple ContextLoader* definitions in your web.xml! at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:265) at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:112) at org.mortbay.jetty.handler.ContextHandler.startContext(ContextHandler.java:549) at org.mortbay.jetty.servlet.Context.startContext(Context.java:136) at org.mortbay.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1282) at org.mortbay.jetty.handler.ContextHandler.doStart(ContextHandler.java:518) at org.mortbay.jetty.webapp.WebAppContext.doStart(WebAppContext.java:499) at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50) at org.mortbay.jetty.handler.HandlerWrapper.doStart(HandlerWrapper.java:130) at org.mortbay.jetty.Server.doStart(Server.java:224) at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50) at runjettyrun.Bootstrap.main(Bootstrap.java:97) 2014-04-03 18:50:42.047:INFO::Started SelectChannelConnector@0.0.0.0:8080

So I found 2 solutions:

1. Remove the inheritance of ContextLoaderListener in my class.
2. Keep the inheritance and remove entry of ContextLoaderListener from web.xml

Both worked for me.

Answer 2

Listeners are called in the order you specify it in web.xml.

    <listener>
        <listener-class>com.license.LicenseCheck</listener-class>
    </listener>

    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>

    public class LicenseCheck  implements   ServletContextListener {
        public void contextInitialized(ServletContextEvent event) {      
        /* This method is called when the servlet context is         
            initialized(web app is deployed/started).          
            You can initialize servlet context related data here.      
        */     
        //Write your logic to check license expiry  
        }    

        public void contextDestroyed(ServletContextEvent event) {      
            /* This method is invoked when the servlet context ( web app) is undeployed or server shuts down.      
            */                  
            //Do nothing
        }   
    }

This way LicenseCheck will execute first and check expiry even before applicationContext is loaded by ContextLoaderListener.