[ACCEPTED]-Register shutDownHook in web application-ioc-container

registerShutdownHook() in standalone (non-web) application:

The @PreDestroy annotation is used on bean method to 10 be notified when the bean is being removed 9 from the context or when the context is 8 shutting down.

Shut down event is fired when 7 context.close() or context.registerShutdownHook() is invoked.

@Component(value="someBean")
public class SomeBean {

    @PreDestroy
    public void destroy() {
        System.out.println("Im inside destroy...");
    }
}

I hope you already know 6 this.

registerShutdownHook() in web application:

In a web application, DispatcherServlet/ContextListener 5 creates the ApplicationContext and it will 4 close the context when the server shutdown. You 3 don't need to explicitly invoke context.close() or context.registerShutdownHook().

When the 2 server shutdown, @PreDestory methods on your bean will 1 be notified automatically.

In web applications, you can use a ServletContextListener which 3 fires when your application is deployed 2 and undeployed:

public class MyServletContextListener implements ServletContextListener {
    public void contextInitialized(ServletContextEvent sce) {
        //application is being deployed
    }
    public void contextDestroyed(ServletContextEvent sce) {
        //application is being undeployed
    }
}

You can access to your Spring 1 beans by retrieving the current Spring context:

public void contextDestroyed(ServletContextEvent sce) {
    ServletContext ctx = sce.getServletContext();
    WebApplicationContext springContext = WebApplicationContextUtils.getWebApplicationContext(ctx);
    //retrieve your Spring beans here...
    SomeSpringBean bean = (SomeSpringBean)ctx.getBean("someSprinbgBean");
    //...
}

Using Spring 3+ you can add a ContextCleanupListener 7 to the application context.

Register your 6 listener at startup like so (you might prefer 5 to use xml config but the same applies)

package com.myapp

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRegistration;

import org.springframework.web.WebApplicationInitializer;
import org.springframework.web.context.ContextCleanupListener;
import org.springframework.web.context.ContextLoaderListener;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;
import org.springframework.web.servlet.DispatcherServlet;

public class MyWebApplicationInitializer implements WebApplicationInitializer {

    @Override
    public void onStartup(ServletContext servletContext)
            throws ServletException {
        WebApplicationContext appContext = getContext();


        servletContext.addListener(new ContextLoaderListener(appContext));

        // line adding an implementation of ContextCleanupListener
        servletContext.addListener(new MyWebApplicationCleanupListener());

        ServletRegistration.Dynamic dispatcher = servletContext.addServlet("DispatcherServlet", new DispatcherServlet(appContext));
            dispatcher.setLoadOnStartup(1);
            dispatcher.addMapping("/");
    }

    private AnnotationConfigWebApplicationContext getContext() { 
        AnnotationConfigWebApplicationContext context = new AnnotationConfigWebApplicationContext();
        context.setConfigLocation("com.myapp");
        return context;
    }
} 

Implementation of ContextCleanupListener that runs your shutdown code:

package com.myapp;

import javax.servlet.ServletContextEvent;
import com.myapp.resources.requiring.clean.shutdown
import org.springframework.web.context.ContextCleanupListener;

public class MyWebApplicationCleanupListener extends ContextCleanupListener {

    @Override
    public void contextDestroyed(ServletContextEvent event) {
        // put your shutdown code in here

        MyResourceNeedingShutdown dataStore = MyResourceNeedingShutdown.getInstance();
        dataStore.shutdown();
    }

}

When 4 you run up say tomcat for example, and press 3 CTRL + C to shut it down, you'll immediately 2 see the contextDestroyed method be hit in 1 the debugger if you put a breakpoint there.

@Luiggi Mendoza answer is started working 15 when i add entry in web.xml.

<web-app ...>
   <listener>
    <listener-class>
             com....MyServletContextListener
        </listener-class>
   </listener>
</web-app>

you can see 14 the stack trace of initialising/notifying 13 the listener object by the tomcat; which 12 is much before spring does.

com....MyServletContextListener.init(nothing but calling @PostConstruct)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.apache.catalina.core.DefaultInstanceManager.postConstruct(DefaultInstanceManager.java:203)
    at org.apache.catalina.core.DefaultInstanceManager.postConstruct(DefaultInstanceManager.java:188)
    at org.apache.catalina.core.DefaultInstanceManager.newInstance(DefaultInstanceManager.java:143)
    at org.apache.catalina.core.DefaultInstanceManager.newInstance(DefaultInstanceManager.java:119)
    at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4649)
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5189)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
    at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:724)
    at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:700)
    at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:734)
    at org.apache.catalina.startup.HostConfig.deployWAR(HostConfig.java:952)
    at org.apache.catalina.startup.HostConfig$DeployWar.run(HostConfig.java:1823)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)

But important 11 thing is @PreDestroy called first by Spring, then 10 after contextDestroyed is called and again 9 @PreDestroy called by non-spring thread.

So 8 if you want to complete some work; on that 7 time if you want to ensure other resource 6 thread are available then hold this @PreDestroy.

@PreDestroy
public void cleanup() {
    eventTaskExecutor.shutdown();
    try {
        /**
         * This is blocking call to avoid other threads (like logger demon thread)
         * not closed before this completes the job. Else worker thread cannot log
         * event.
         * 
         * This will be the case when thread is busy in getting the web response,
         * better will wait for that, and log the web response.
         * 
         */
        eventTaskExecutor.awaitTermination(20, TimeUnit.SECONDS);
    } catch (InterruptedException e) {
        e.printStackTrace();
    }   
}

Just 5 know that the below is one more way of getting 4 the @postConstruct hook within the class.

@Autowired
public void setApplicationContext(ApplicationContext applicationContext) {
    applicationContext.getBean("myRelatedClass", MyRelatedClass.class);
}

One 3 more thing is @PreDestroy is called only 2 for singleton objects not available for 1 prototype objects.