Starting the servlet when the application startup

Question

I want to starting by fireing the servlet class before loading a jsp page, because i need to populate some data from the database in a jsp page. Servlet mapping in web.xml

    <servlet>
        <servlet-name>Index</servlet-name>
        <servlet-class>com.Teklabz.Servlets.IndexServlet</servlet-class>
        <load-on-startup>1</load-on-startup>
    </servlet>

    <servlet-mapping>
        <servlet-name>Index</servlet-name>
        <url-pattern>/index</url-pattern>
    </servlet-mapping>

but it didn't work, when tracing the code it's never reach the servlet class. Also i was trying to use ServletContextListener like this link, but I faced the same problem.

listener code:

public class ServletListener implements ServletContextListener{

    @Override
    public void contextInitialized(ServletContextEvent sce) {
        throw new UnsupportedOperationException("Not supported yet.");
    }

    @Override
    public void contextDestroyed(ServletContextEvent sce) {
        throw new UnsupportedOperationException("Not supported yet.");
    }
}

web.xml code:

    <listener>
        <listener-class>com.techlabz.listener.ServletListener</listener-class>
    </listener>

I don't know what am doing wrong.

Answer 1

There are number of ways you can achieve this ..

1. Either you can populate the data in service method com.Teklabz.Servlets.IndexServlet and then set the data in request attribute and then forward to that jsp.
2. If you want to use loadonstartiup then you can populate the data from db in com.Teklabz.Servlets.IndexServlet servlet's init method and then set it in some accessible scope(request,session,context) and by direct accessing jsp get the data from that scope.
3. In listener also you can do this but in that case also you need to set the data in some scope.

Answer 2

your code is absolutely right.you need to Add annotation @WebListener

  @WebListener
   public class ServletListener implements ServletContextListener{
    //your code
   }