ServletContext Listener August 24, 2005
Posted by Coolguy in Java.Tags: Servlets
trackback
- 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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