java examples
Home Java Examples Resources Java Interview Questions
Brainpower SEO

How to read servlet context initilization parameters?

package com.javacoderanch.example.servlet;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Enumeration;

import javax.servlet.Servlet;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class ContextInitParameter extends HttpServlet implements Servlet {

    public ContextInitParameter() {
    }

    protected void doGet(HttpServletRequest request,
	    HttpServletResponse response) throws ServletException, IOException {
	doPost(request, response);
    }

    protected void doPost(HttpServletRequest request,
	    HttpServletResponse response) throws ServletException, IOException {
	response.setContentType("text/html");
	PrintWriter writer = response.getWriter();
	
	//
	// Get an instance of ServletContext
	//
	ServletContext context = getServletContext();
	
	//
	// To read context initialization parameter we can call context.getInitParameter() 
	// and pass the name of initialization parameter to be read. If the named
	// parameter does not exists the returned value will be null. 
	//
	// In this example we read an initialization parameter called LOG.PATH
	//
	String logPath = context.getInitParameter("LOG.PATH");
	writer.println("Log Path: " + logPath + "<br/>");
	
	//
	// Reads all the name of servlet's initialization parameters. If the
	// servlet doesn't have any an empty enumeration will be returned.
	//
	Enumeration enumeration = context.getInitParameterNames();
	while (enumeration.hasMoreElements()) {
	    String paramName = (String) enumeration.nextElement();
	    String paramValue = context.getInitParameter(paramName);	    	   

	    writer.println("Context Init Param: [" + paramName + " = " + paramValue + "]<br/>");
	}
    }
}