ServletContext Listener

• To listen for ServletContext events write a listener class that implements
  javax.servlet.ServletContextListener;
  and tell the container by putting a <listener> element in DD.
• This class will get notifed when context is initialized and destroyed
• E.g:
  web.xml
  <context-param>
  <param-name>breed</param-name>
  <param-value>poodle</param-value>
  </context-param>
  <listener>
  <listener-class>
  test.MyServletContextListener
  </listener-class>
  </listener>
  <servlet>
  <description></description>
  <display-name>ListenerTest</display-name>
  <servlet-name>ListenerTest</servlet-name>
  <servlet-class>test.ListenerTest</servlet-class>
  </servlet>
  Listener Class
  import javax.servlet.*;
  public class MyServletContextListener implements ServletContextListener{
  public void contextInitialized(ServletContextEvent se)
  {
  ServletContext sc=se.getServletContext();
  String breed=sc.getInitParameter(“breed”);
  Dog d = new Dog(breed);
  sc.setAttribute(“dog”,d);
  }
  public void contextDestroyed(ServletContextEvent se)
  {
  }
  }
  Testing servlet
  import java.io.IOException;
  import java.io.PrintWriter;import javax.servlet.ServletException;
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;

  public class ListenerTest extends javax.servlet.http.HttpServlet implements javax.servlet.Servlet {
  public ListenerTest()
  {
  super();
  }

  protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
  {
  response.setContentType(“text/html”);
  PrintWriter out = response.getWriter();
  Dog dog = (Dog) getServletContext().getAttribute(“dog”);
  out.println(dog.getBreed());
  }

  protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
  {
  // TODO Auto-generated method stub
  }
  }

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