Dr R Anurekha: apache tomcat server

Showing posts with label apache tomcat server. Show all posts

Hit Counter

Simple program to demonstrate accessing a servlet in Apache Tomcat Server

Hit counter program

import javax.servlet.http.*;

import javax.servlet.*;

import java.io.*;

public class HitCounter extends HttpServlet

{

private int counter = 0;

public void doGet(HttpServletRequest req,HttpServletResponse res)

throws ServletException, IOException

{

//setting the content type

res.setContentType("text/html");

//create the stream to write the data

PrintWriter pw=res.getWriter();

counter++;

//writing html in the stream

pw.println("<html><body>");

pw.println("<h2>Hit Count = "+counter+"</h2>");

pw.println("</body></html>");

//closing the stream

pw.close();

}

Session Management using HttpSession

Program to demonstrate session management using HttpSession

// Session management

import javax.servlet.http.*;

import javax.servlet.*;

import java.io.*;

import java.util.*;

public class SessionMgt extends HttpServlet

{

private int counter = 0;

public void doGet(HttpServletRequest req,HttpServletResponse res)

throws ServletException, IOException

{

//setting the content type

res.setContentType("text/html");

//create the stream to write the data

PrintWriter pw=res.getWriter();

counter++;

//writing html in the stream

pw.println("<html>");

pw.println("<head>");

pw.println("<title>Session</title>");

pw.println("</head>");

pw.println("<body><h3>");

pw.println("<center>");

pw.println("<h2>Servlet Session Management</h2><hr/><br/>");

HttpSession hs = req.getSession(true);

// Display date/time of last access.

Date dt = (Date)hs.getAttribute("date");

if(dt != null)

{

pw.println("Last access: " + dt + "<br/><br/>");

}

// Display current date/time

dt = new Date();

hs.setAttribute("date", dt);

pw.println("Current date: " + dt+ "<br/><br/>");

pw.println("<hr/>Hit Count = "+counter);

pw.println("</center>");

pw.println("</h3></body></html>");

//closing the stream

pw.close();

}

Simple Welcome Servlet

Simple program to access a servlet and display a welcome message

import javax.servlet.http.*;

import javax.servlet.*;

import java.io.*;

public class WelcomeServlet extends HttpServlet

{

public void doGet(HttpServletRequest req,HttpServletResponse res)

throws ServletException, IOException

{

//setting the content type

res.setContentType("text/html");

//create the stream to write the data

PrintWriter pw=res.getWriter();

//writing html in the stream

pw.println("<html><body>");

pw.println("<center><h2>Welcome to servlet</h2></center>");

pw.println("</body></html>");

//closing the stream

pw.close();

}

Deploying a Servlet in Apache Tomacat Server

Deploying a Servlet in Apache Tomcat Server

Steps to Deploy a Servlet in Apache Tomcat Server

§ Create a directory structure under Tomcat for your application.

o Inside the webapps folder of apache tomcat server create a folder (Example WT).

o Inside this new folder (WT) create a folder called WEB-INF

o Inside WEB-INF create a folder called classes.

o Create a web.xml file in WEB-INF

o The html and jsp files should be saved in WT folder.

Directory Structure

§ Copy the servlet-api.jar file from …\apache-tomcat-9.0.24\lib to …\jre1.8.0_221\lib\ext

§ Set path variable to Java compiler and classpath variable to the servlet-api.jar file

(path=C:\Program Files\Java\jdk1.8.0_221\bin)

(classpath=C:\Program Files\Java\jre1.8.0_221\lib\ext\servlet-api.jar)

§ Write the servlet source code and Compile. Copy the .class file to the classes folder created in tomcat server. (Example – WelcomeServlet.java)

§ Create a deployment descriptor for the servlet in web.xml.

Example:

<servlet-name>WelcomeServlet</servlet-name>

<servlet-class>WelcomeServlet</servlet-class>

</servlet>

<servlet-mapping>

<servlet-name>WelcomeServlet</servlet-name>

<url-pattern>/WelcomeServlet</url-pattern>

</servlet-mapping>

§ Start the Tomcat server and call the servlet from a web browser.

web.xml file:

<?xml version="1.0" encoding="ISO-8859-1"?>

<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-name>WelcomeServlet</servlet-name>

<servlet-class>WelcomeServlet</servlet-class>

</servlet>

<servlet-mapping>

<servlet-name>WelcomeServlet</servlet-name>

<url-pattern>/WelcomeServlet</url-pattern>

</servlet-mapping>

</web-app>