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Servlet Init parameters and ServletConfig interface

Init parameters:

Init parameters refers to the initialization parameters of a servlet or filter. <init-param> attribute is used to define a init parameter. <init-param> attribute has two main sub attributes <param-name> and <param-value>. The <param-name> contains the name of the parameter and <param-value> contains the value of the parameter.

ServletConfig interface:

ServletConfig interface is used to access the init parameters.

Methods of ServletConfig interface:

1. getInitParameter(String name): Returns the value of the specified parameter if parameter exist otherwise return null.

Syntax: public String getInitParameter(String name)

2. getInitParameterNames(): Returns the names of init parameters as Enumeration if servlet has init parameters otherwise returns an empty Enumeration.

Syntax: public Enumeration getInitParameterNames()

3. getServletContext():Returns an instance of ServletContext.

Syntax: public ServletContext getServletContext()

4. getServletName():Returns the name of the servlet.

Syntax: public String getServletName()



import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
 * This class is used to show the use of init parameters.
 * @author javawithease
public class InitParamExample extends HttpServlet {
	private static final long serialVersionUID = 1L;
        //no-argument constructor
        public InitParamExample() {
      protected void doGet(HttpServletRequest request, 
		HttpServletResponse response)
	          throws ServletException, IOException {
    	PrintWriter out = response.getWriter();
    	//get ServletConfig object.
    	ServletConfig config=getServletConfig(); 
    	//get init parameter from ServletConfig object.
    	String appUser = config.getInitParameter("appUser");
    	out.print("<h1>Application User: " + appUser + "</h1>");


<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
id="WebApp_ID" version="2.5">


servlet example 7
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