ServletContextListener

ServletContextListener

source codes for this program:

1.Dog.java

package com.example;

public class Dog {
private String breed;
public Dog(String breed) {
this.breed = breed;
}
public String getBreed() {
return breed;
}
}


2.ListenerTester.java

package com.example;
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;

public class ListenerTester extends HttpServlet {
public void doGet (HttpServletRequest request, HttpServletResponse response)
throws IOException, ServletException {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
out.println("test context attributes set by listener");
out.println("
");
Dog dog = (Dog)getServletContext().getAttribute("dog");
out.println("Dog's breed is: " + dog.getBreed());
}
}


3.
MyServletContextListener.java

package com.example;
import javax.servlet.*;
public class MyServletContextListener implements ServletContextListener {
public void contextInitialized(ServletContextEvent event) {
ServletContext sc = event.getServletContext();
String dogBreed = sc.getInitParameter("breed");
Dog d = new Dog(dogBreed);
sc.setAttribute("dog", d);
}
public void contextDestroyed(ServletContextEvent event) {
// nothing to do here
}
}


4.
Web.xml

<web-app xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"
version="2.4">
<servlet>
< servlet-name>ListenerTester </servlet-name>
< servlet-class>com.example.ListenerTester </servlet-class>

</servlet>
<servlet-mapping>
<servlet-name>ListenerTester </servlet-name>
<url-pattern> /ListenTest.do </url-pattern>

</servlet-mapping >
<context-param>
<param-name>breed </param-name>
<param-value>Great Dane </param-value>
</context-param>

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

Servlet Example(free Source codes )

# Writing MyFirstServlet.java file

//Import needed Java packages
package MyFirstServlet;
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;

/**Example servlet showing First Hello World Servlet
*@author Nadishan Mayura
*/
// Create a class which inherits from GenericServlet or HttpServlet.
public class MyFirstServlet extends HttpServlet{

/**
* Override the service method.
* Here we handle the HTTP GET method by building a simple web page.
*/

public void doGet(HttpServletRequest req,HttpServletResponse res)throws
ServletException,IOException{
PrintWriter out=res.getWriter();// write the data of the response
out.println("Hello World!!!!!!!");
java.util.Date today=new java.util.Date();
out.println("The date & Time of Today is:"+today);
}
}

# Writing web.xml file

<?xml version="1.0" encoding="ISO-8859-1"?>

<web-app xmlns="http://java.sun.com/xml/ns/j2ee"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee

http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd" version="2.4">



<servlet>
<servlet-name>myfirstservlet</servlet-name>
<servlet-class>MyFirstServlet.MyFirstServlet</servlet-class>
</servlet>

<!-- servlet mappings start -->
<servlet-mapping>
<servlet-name>myfirstservlet </servlet-name >
<url-pattern>/hello </url-pattern>
</servlet-mapping>
<!-- servlet mappings end -->

</web-app>