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Saturday, 5 April 2014

Servlet – Read Init Param using Servlet Config

In this tutorials we are going to see, How to read multiple init-param values using ServletConfig interface. In previous tutorials I explained about ServletConfig interface with example program (read single init-param).Click here to read more about ServletConfig Interface
1. Create new Dynamic web project by choosing File –> New –> Dynamic Web Project .
2. Create the Project called ServletExample as given below.
Servlet-dynamic web project
3. Create package called com.javatutorialscorner.servlet under ServletExample.
4. Create Servlet called ServletConfigExample as shown in figure.
Create Servlet
http servlet
5. Click Next it will show URL mapping.You can edit Servlet URL if you need.
6. Click Next it will show methods available  in HttpServlet. Select appropriate method you need.
http servlet Services
7. By default your servlet will be mapped in web.xml, if your servlet not mapped in your web.xml use the following configuration to map the servlet in your web.xml
Servlet Mapping
<servlet>
    <servlet-name>Your Servlet Name</servlet-name>
    <servlet-class>Fully Qulaified Servlet Class Name</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>Your Servlet Name</servlet-name>
    <url-pattern>/URL to Call Servlet</url-pattern>
  </servlet-mapping>

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
 xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
 id="WebApp_ID" version="3.0">
 <display-name>ServetExample</display-name>
 <welcome-file-list>
  <welcome-file>index.html</welcome-file>
  <welcome-file>index.htm</welcome-file>
  <welcome-file>index.jsp</welcome-file>
  <welcome-file>default.html</welcome-file>
  <welcome-file>default.htm</welcome-file>
  <welcome-file>default.jsp</welcome-file>
 </welcome-file-list>
 <servlet>
  <servlet-name>ServletConfigExample</servlet-name>
  <servlet-class>com.javatutorialscorner.servlet.ServletConfigExample</servlet-class>
  <init-param>
   <param-name>path</param-name>
   <param-value>JTC</param-value>
  </init-param>
  <init-param>
   <param-name>Tutorial</param-name>
   <param-value>Servlet</param-value>
  </init-param>
 </servlet>
 <servlet-mapping>
  <servlet-name>ServletConfigExample</servlet-name>
  <url-pattern>/ServletConfigExample</url-pattern>
 </servlet-mapping>
</web-app>

<init-param>....</init-param>

The init-param is sub element of servlet which is used to pass the Initialization parameter to Servlet

8. Add the required code inside doGet() method.

ServletConfigExample.java

package com.javatutorialscorner.servlet;

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;

/**
 * Servlet implementation class ServletConfigExample
 */

public class ServletConfigExample extends HttpServlet {
 private static final long serialVersionUID = 1L;

 /**
  * @see HttpServlet#HttpServlet()
  */
 public ServletConfigExample() {
  super();
  // TODO Auto-generated constructor stub
 }

 /**
  * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse
  *      response)
  */
 protected void doGet(HttpServletRequest request,
   HttpServletResponse response) throws ServletException, IOException {
  // TODO Auto-generated method stub

  response.setContentType("text/html");
  PrintWriter writer = response.getWriter();
  writer.write("<!DOCTYPE html PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\" \"http://www.w3.org/TR/html4/loose.dtd\">\n"
    + "<html><head><meta http-equiv=\"Content-Type\" content=\"text/html; charset=ISO-8859-1\"><title>Java Tutorials Corner - Servlet - Read Init Param using ServletConfig </title>"
    + "</head><body><h1>Java Tutorials Corner - Servlet - Read Init Param using ServletConfig</h1><table>");
  writer.write("<tr><td> Init Param Name </td><td> Param Value</td></tr>");
  ServletConfig servletConfig = getServletConfig();
  Enumeration<String> initParams = servletConfig.getInitParameterNames();

  while (initParams.hasMoreElements()) {
   String paramName = (String) initParams.nextElement();
   writer.write("<tr><td> " + paramName + "</td><td>"
     + servletConfig.getInitParameter(paramName) + "</td></tr>");
  }

  writer.write("</table></body></html>");
 }

 /**
  * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse
  *      response)
  */
 protected void doPost(HttpServletRequest request,
   HttpServletResponse response) throws ServletException, IOException {
  // TODO Auto-generated method stub
 }

}

9. Now save and Run the servlet, Run As –> Run on Server – Select your web Server to run the servlet. ( see How to configure tomcat in eclipse) 
http://www.javatutorialcorner.com/2014/03/how-to-configure-tomcat-in-eclipse.html

10.call the URL which is mapped in web.xml.

http://localhost:8080/ServletExample/ServletConfigExample

Output

image
Annamalai Thangaraj

Annamalai is working as Technical Lead in Leading Telecom company with 5+ years experience in Identity and Access Management , Telecom and Networks, BigData, Java, Spring, Struts, Hibernate, AngularJS, and Enterprise Web Application Development.

Website: Java Tutorials Corner

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Item Reviewed: Servlet – Read Init Param using Servlet Config Rating: 5 Reviewed By: Annamalai Thangaraj