ServletContext Interface

Object of ServletContext Interface is used get parameter value corresponding to parameter name and in a web Application there is only one ServletContext object.

Using parameter name we can share corresponding value to more than one servlet by invoking parameter name in that servlet using ServletContext object.

It is better to change data values at one place rather than changing in all servlets.
web.xml

 <?xml version="1.0" encoding="UTF-8"?>  
 <web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">  
   <servlet>  
     <servlet-name>ServletContextDemo</servlet-name>  
     <servlet-class>ServletContextDemo</servlet-class>  
     <init-param>  
       <param-name>d1</param-name>  
       <param-value>oracle.jdbc.driver.OracleDriver</param-value>  
     </init-param>  
     <init-param>  
       <param-name>d2</param-name>  
       <param-value>jdbc:oracle:thin:@localhost:1521:XE</param-value>  
     </init-param>  
   </servlet>  
   <servlet-mapping>  
     <servlet-name>ServletContextDemo</servlet-name>  
     <url-pattern>/ServletContextDemo</url-pattern>  
   </servlet-mapping>  
   <session-config>  
     <session-timeout>  
       30  
     </session-timeout>  
   </session-config>  
   <welcome-file-list>  
     <welcome-file>index.jsp</welcome-file>  
   </welcome-file-list>  
 </web-app>  

ServetContextDemo.java
we can create object of ServletContext by two ways which are shown below.

 import java.io.IOException;  
 import javax.servlet.ServletException;  
 import javax.servlet.http.HttpServlet;  
 import javax.servlet.http.HttpServletRequest;  
 import javax.servlet.http.HttpServletResponse;  
 import java.sql.*;  
 import javax.servlet.ServletContext;  
  
 public class ServletContextDemo extends HttpServlet {   
   protected void doGet(HttpServletRequest req, HttpServletResponse res)  
   throws ServletException, IOException {  
       
     //Method 1 to get object of ServletContext  
     ServletContext context1=getServletContext();  
     //Method 2 to get object of ServletContext  
     ServletContext context2=getServletConfig().getServletContext();  
     String dd1=context1.getInitParameter("d1");  
     String dd2=context2.getInitParameter("d2");  
      
     try{  
       Class.forName(dd1);  
       Connection connection=DriverManager.getConnection(dd2,"hr","hr");  
        }  
     catch(Exception e){ }  
   }   
 }  

Setting and getting Attribute using ServletContext Object
public void setAttribute(String name,Object object);
Binds an object to a given attribute name in this ServletContext. If the name specified is already used for an attribute, this method will replace the attribute with the new to the new attribute.     

page1.java
getServletContext().setAttribute("myString", s1);

public Object getAttribute(String name);
Returns the servlet container attribute with the given name, or null if there is no attribute by that name.     

page2.java

getServletContext().getAttribute("myString");

More Servlet Topics :

• Introduction : Servlet Interface
• Java Package javax.servlet(Interfaces,Classes and Methods)
• Java Package javax.servlet.http (Interfaces,Classes and Methods)
• How to Create a Web Application using NetBeans and Apache Tomcat Server
• Basic Program using HttpServlet Class 
• Basic Login Program using JSP and GenericSevlet class
• Login using JDBC,Servlet with NetBeans and Oracle 
• SevletConfig Interface using JDBC,NetBeans 6.9 and Oracle 10g 
• Validation on TextField using JavaScript and Print command using servlet on NetBeans 
• ServletContext Interface 
• RequestDispatcher Interface and SendRedirect() Method 
• Session Tracking 
• Session Tracking using Cookies  
• Session Tracking using HttpSession Interface 
• Session Tracking using URL Rewriting  
• Session Tracking using Hidden Forms Field 
• Sql Query Tool using Servlet