2

I need to get a proxied session-scoped bean on the HttpSessionListener.sessionDestroyed(). The objective is doing a session cleanup when it gets destroyed (either by invalidate() or timeout). I added the ContextLoaderListener to expose the context and got the bean through WebApplicationContextUtils.getWebApplicationContext().

Everything works fine if I invalidate the session myself in a Servlet, but when session times out I get an Scope 'session' is not active for the current thread;. I understand that the problem happens for the cleanup is being done by a internal thread of the Servlet engine, but I still need to be able to get this bean from a HttpSessionListener.

I've seem many of the same question around, no one got a solution, this is why I'm asking again.

My applicationContext.xml has no bean declaration, as I'm using annotations.

This the bean I need to access when session times out:

@Component
@Scope(value="session", proxyMode=ScopedProxyMode.TARGET_CLASS)
public class Access {

    static private int SERIAL = 0;
private int serial;

    public Access() {
            serial = SERIAL++;
    }

    public int getSerial() {
            return serial;
    }
}

This is the controller that either create or destroy the session manually.

@Controller
public class Handler {

    @Autowired
    Access access;


    @RequestMapping("/create")
    public @ResponseBody String create() {
        return "Created "+access.getSerial();
    }

    @RequestMapping("/destroy")
    public @ResponseBody String destroy(HttpSession sess) {
        int val = access.getSerial();
        sess.invalidate();
        return "Destroyed "+val;
    }

}

And this is the HttpSessionListener that listen to the session destruction, where I need to access the the contents of the Access session scoped bean.

public class SessionCleanup implements HttpSessionListener {

@Override
public void sessionDestroyed(HttpSessionEvent ev) {

    // Get context exposed at ContextLoaderListener
    WebApplicationContext ctx = WebApplicationContextUtils
        .getWebApplicationContext(ev.getSession().getServletContext());

    // Get the beans
    Access v = (Access) ctx.getBean("access");

    // prints a not-null object
    System.out.println(v);

    // this line raise the exception
    System.out.println(v.getSerial());

    }


    @Override
    public void sessionCreated(HttpSessionEvent ev) {/*Nothing to do*/}

}

The exception below is raised at v.getSerial().

Ago 14, 2012 11:44:58 PM org.apache.catalina.session.StandardSession expire
SEVERE: Session event listener threw exception
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'scopedTarget.access': Scope 'session' is not active for the current thread; consider defining a scoped proxy for this bean if you intend to refer to it from a singleton; nested exception is java.lang.IllegalStateException: No thread-bound request found: Are you referring to request attributes outside of an actual web request, or processing a request outside of the originally receiving thread? If you are actually operating within a web request and still receive this message, your code is probably running outside of DispatcherServlet/DispatcherPortlet: In this case, use RequestContextListener or RequestContextFilter to expose the current request.
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:342)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:193)
    at org.springframework.aop.target.SimpleBeanTargetSource.getTarget(SimpleBeanTargetSource.java:33)
    at org.springframework.aop.framework.Cglib2AopProxy$DynamicAdvisedInterceptor.getTarget(Cglib2AopProxy.java:654)
    at org.springframework.aop.framework.Cglib2AopProxy$DynamicAdvisedInterceptor.intercept(Cglib2AopProxy.java:605)
    at model.Access$$EnhancerByCGLIB$$438f41a5.toString(<generated>)
    at java.lang.String.valueOf(String.java:2902)
    at java.io.PrintStream.println(PrintStream.java:821)
    at org.apache.tomcat.util.log.SystemLogHandler.println(SystemLogHandler.java:242)
    at service.SessionCleanup.sessionDestroyed(SessionCleanup.java:24)
    at org.apache.catalina.session.StandardSession.expire(StandardSession.java:709)
    at org.apache.catalina.session.StandardSession.isValid(StandardSession.java:576)
    at org.apache.catalina.session.ManagerBase.processExpires(ManagerBase.java:712)
    at org.apache.catalina.session.ManagerBase.backgroundProcess(ManagerBase.java:697)
    at org.apache.catalina.core.ContainerBase.backgroundProcess(ContainerBase.java:1364)
    at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1649)
    at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1658)
    at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1658)
    at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.run(ContainerBase.java:1638)
    at java.lang.Thread.run(Thread.java:722)
Caused by: java.lang.IllegalStateException: No thread-bound request found: Are you referring to request attributes outside of an actual web request, or processing a request outside of the originally receiving thread? If you are actually operating within a web request and still receive this message, your code is probably running outside of DispatcherServlet/DispatcherPortlet: In this case, use RequestContextListener or RequestContextFilter to expose the current request.
    at org.springframework.web.context.request.RequestContextHolder.currentRequestAttributes(RequestContextHolder.java:131)
    at org.springframework.web.context.request.SessionScope.get(SessionScope.java:90)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:328)
    ... 19 more

Finally, here is my web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app 
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xmlns="http://java.sun.com/xml/ns/javaee" 
    xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" 
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" 
    id="WebApp_ID" version="2.5">

  <display-name>session-listener-cleanup</display-name>


    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>/WEB-INF/spring-config.xml</param-value>
    </context-param>


    <listener>
      <listener-class>org.springframework.web.context.request.RequestContextListener</listener-class>
    </listener>

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


    <listener>
      <listener-class>service.SessionCleanup</listener-class>
    </listener>


    <servlet>
        <servlet-name>appServlet</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>/WEB-INF/spring-config.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>

    <servlet-mapping>
        <servlet-name>appServlet</servlet-name>
        <url-pattern>/*</url-pattern>
    </servlet-mapping>


    <session-config>
      <session-timeout>1</session-timeout>
    </session-config>


</web-app>

As I've said, everything goes nice when I invalidate the session at the controller's method destroy.

UPDATE 1: POSSIBLE SOLUTIONS FOUND

The problem happens because a request is needed in order to Spring access session beans. Event though we have a Context associated to the Thread, there is no request.

There are some possible choices here:

  1. Implement the interface DisposableBean, as suggested by alexwen. This would imply in moving business logic to the model object [here];
  2. Implement the DestructionAwareBeanPostProcessor also suggested by alexwen. This one would mean that you would need to check if the bean being disposed is a Access or not before doing any disposal [here];
  3. Retrieve the bean directly from the session. This way is not a very good one, as you use an undocumented behavior to achieve the result, but does work [here];
  4. Mock a servlet request and bind it's attributes to the Thread through RequestContextHolder. This also leads to undocumented behavior, able of being changed in future releases [here];

I didn't chose the last two, for they're not documented. Also, I didn't like the idea of scavenging every bean after a specific one. As I also don't want to mix the business logic into my model beans, I ended up by creating a @Service that creates the bean and also have a destroy method.

This method is responsible by the disposal of the access bean. I implemented the DisposableBean interface on the Access and injected the AccessManager service to the Access bean and call the service destroy method. The service look like this:

@Service
public class AccessManager {

    @Bean(name="access", destroyMethod="destroy")
    @Scope(value="session", proxyMode=ScopedProxyMode.TARGET_CLASS)
    @Autowired
    public Access create(HttpServletRequest request) {
        // creation logic
    }


    public void destroy(Access access) {
        // disposal logic
    }

}
Community
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Caio Cunha
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  • As suggested by the exception, in the web.xml, you should use either DispatcherServlet or RequestContextListener/RequestContextFilter expose all http requests and bind request to thread. – yorkw Aug 15 '12 at 04:17
  • @yorkw the listener is already registered and everything goes fine if I invalidate the session. The problem is the timeout. I've updated the post to include my **web.xml**. – Caio Cunha Aug 15 '12 at 12:24

2 Answers2

3

If you implement the interface, DisposableBean on your Access class Spring will invoke the method "destroy" when the Session is destroyed.

Alternatively, you can register with Spring a DestructionAwareBeanPostProcessor which will have the opportunity to process all beans in the Session scope when the scope is destroyed. Docs and instructions here.

If you are curious as to how Spring does all this I would encourage you to look at the DisposableBeanAdapter which Spring registers as a HttpSessionBindingListener with the Session.

Caio Cunha
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alexwen
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  • Thanks. The destroy method does work, and I had already tried this. But this would imply in moving business logic to my model beans. I'd like to avoid it, and make services that could cleanup the mess. I'll take a look at `DestructionAwareBeanPostProcessor` and `HttpSessionBidingListener`. – Caio Cunha Aug 15 '12 at 12:37
  • It did work with `DestructionAwareBeanPostProcessor`, but then I'll need to watch every bean on the application and look for the `Access` instances? There is no way to watch for specific instances? Gonna give a look and search for a scope destruction awareness. Thanks. – Caio Cunha Aug 15 '12 at 14:51
  • Spring offers no means to filter beans passed to the PostProcessor, that I can see. Generally, I have seen with the *Aware interfaces in Spring is that they operate on all beans in the Context. One potential way around that (as you seem adverse to doing instanceof checks) would be to create a specific context for beans you want to be aware of their destruction. – alexwen Aug 16 '12 at 05:12
2

The problem happens for there is no request bound to the listener, although there is a context bound to it. The session scope needs a request to be resolved.

Reading around, I found that the scope beans are stored into the HttpSession itself. If all I need is to grab a session-scoped bean, I just need to get the session attribute with the bean name (session.getAttribute('beanName')).

The only trick here is that proxied beans, as is the case above, are prefixed with the string scopedTarget., so to grab the Access bean, I just need to call the attribute named scopedTarget.access. No need for the ContextLoaderListener also.

All I need to do, to get the bean above, is to implement HttpSessionListener and write the following method:

@Override
public void sessionDestroyed(HttpSessionEvent ev) {

    // Get the session
    HttpSession session = ev.getSession();

    // Get the access bean
    Access access = (Access) session.getAttribute("scopedTarget.access");

    // Print the serial
    System.out.println(access.getSerial());

}

IMPORTANT: I don't know if this is the best approach, though. I believe this is risky, for there is no guarantees that the bean name will keep the same rules as now.

Caio Cunha
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    Your last statement I believe is the most important. Since this is undocumented behavior and just a side effect of their implementation in Spring it may not be supported in future releases. – alexwen Aug 16 '12 at 05:15
  • I'll try to investigate the best way to grab these attributes and if this is recommended to get this way. – Caio Cunha Aug 16 '12 at 13:06
  • Still useful info in 2021 – mjj1409 Jun 29 '21 at 21:49