Add ServletContextAttributeListener Using addListener

import javax.servlet.ServletContextAttributeEvent;
import javax.servlet.ServletContextAttributeListener;

public class ContextAttrListener implements ServletContextAttributeListener {

    @Override
    public void attributeAdded(ServletContextAttributeEvent event) {
        System.out.println("Attribute " + event.getName() + " Added");
    }

    @Override
    public void attributeRemoved(ServletContextAttributeEvent event) {
        System.out.println("Attribute " + event.getName() + " Removed");
    }

    @Override
    public void attributeReplaced(ServletContextAttributeEvent event) {
        System.out.println("Attribute " + event.getName() + " Replaced");
    }
}

import javax.servlet.*;
import javax.servlet.annotation.WebListener;

@WebListener
public class ContextListener1 implements ServletContextListener {

    @Override
    public void contextInitialized(ServletContextEvent sce) {
        ServletContext context = sce.getServletContext();
        
        /* Add Context Listener */
        System.out.println("Adding Context Attribute listener");
        context.addListener(ContextAttrListener.class);
     
        System.out.println("Context Listener1 Initialized");
        
    }

    @Override
    public void contextDestroyed(ServletContextEvent sce) {
        System.out.println("Context Listener1 Destroyed");
    }
}

import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.*;
import javax.servlet.*;

@WebServlet(urlPatterns = {"/SampleApp"})
public class SampleApp extends HttpServlet {
    @Override
    public void doGet(HttpServletRequest req, HttpServletResponse res)throws IOException{
        try(PrintWriter out = res.getWriter()){
            ServletContext context = req.getServletContext();
            
            System.out.println("Adding Attribute to Servlet Context");
            context.setAttribute("myName", "Krishna");
            
            System.out.println("Replacing Attribute from Servlet Context");
            context.setAttribute("myName", "abcd");
            
             System.out.println("Removing Attribute from Servlet Context");
            context.removeAttribute("myName");
        }
    }
}

context.addListener(ContextAttrListener.class);

Above statement add the Attribute listener ' ContextAttrListener' to the servlet context.

Run ' SampleApp', server console has messages like below.

Info:   Adding Context Attribute listener
Info:   Context Listener1 Initialized
Info:   Attribute com.sun.enterprise.web.WebModule.DeploymentContext Removed
Info:   Attribute com.sun.enterprise.web.WebModule.isDistributable Removed
Info:   Attribute com.sun.enterprise.web.WebModule.enableHA Removed
Info:   Attribute com.sun.jsp.taglibraryCache Added
Info:   Attribute com.sun.jsp.tagFileJarUrlsCache Added
Info:   Loading application [servlet] at [/servlet]
Info:   servlet was successfully deployed in 258 milliseconds.
Info:   Adding Attribute to Servlet Context
Info:   Attribute myName Added
Info:   Replacing Attribute from Servlet Context
Info:   Attribute myName Replaced
Info:   Removing Attribute from Servlet Context
Info:   Attribute myName Removed

Prevoius                                                 Next                                                 Home