How to use Servlets Initialization Parameters through ServletConfig object in Java EE Application ?.

A simple Servlet code to demonstrate how to use Servlets Initialization Parameters through ServletConfig object in Java EE Application.

1. Implementing Initialization Parameters in web.xml as name/value pair.

<?xml version="1.0" encoding="UTF-8"?> <web-app version="3.0" 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_3_0.xsd"> <servlet> <servlet-name>InitParameterDemo</servlet-name> <servlet-class>com.hubberspot.init.parameter.InitParameterDemo</servlet-class> <init-param> <param-name>Username</param-name> <param-value>Jontymagicman</param-value> </init-param> <init-param> <param-name>Website</param-name> <param-value>Hubberspot</param-value> </init-param> <init-param> <param-name>Email</param-name> <param-value>jonty@hubberspot.com</param-value> </init-param> </servlet> <servlet-mapping> <servlet-name>InitParameterDemo</servlet-name> <url-pattern>/InitParameterDemo</url-pattern> </servlet-mapping> <session-config> <session-timeout> 30 </session-timeout> </session-config> </web-app>

2. Servlet Code using Initialization Parameters implemented above in web.xml

package com.hubberspot.init.parameter;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Enumeration;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;


public class InitParameterDemo extends HttpServlet {
    
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        
        response.setContentType("text/html");
        
        PrintWriter out = response.getWriter();
        
         try {
            
            out.println("");
            out.println("");
            out.println("");            
            out.println("");
            out.println("");
            out.println("

Init-Parameters Demo (ServletConfig)
");
            
            ServletConfig config = this.getServletConfig();
            
            Enumeration params = config.getInitParameterNames();
            
            int counter = 1;
            
            while(params.hasMoreElements()){
            
                String paramName = (String) params.nextElement();
                out.print(counter + ". param name = " + paramName + "");
                out.println("
"+ counter + ". param value = " + config.getInitParameter(paramName) + "
");
                counter++;
                
            }
            
            out.println("Username is : " + config.getInitParameter("Username") + "" );
            out.println("Email is : " + config.getInitParameter("Email") + "" );
            out.println("Website is : " + config.getInitParameter("Website") + "" );
            
            out.println("");
            out.println("");
        } finally {            
            out.close();
        }
        
    }
}

Output of the program :