Many times you would be interested in knowing total number of hits on a particular page of your website. It is very simple to count these hits using a servlet because the life cycle of a servlet is controlled by the container in which it runs.

Following are the steps to be taken to implement a simple page hit counter which is based on Servlet Life Cycle −

Initialize a global variable in init() method.
Increase global variable every time either doGet() or doPost() method is called.
If required, you can use a database table to store the value of global variable in destroy() method. This value can be read inside init() method when servlet would be initialized next time. This step is optional.
If you want to count only unique page hits with-in a session then you can use isNew() method to check if same page already have been hit with-in that session. This step is optional.
You can display value of the global counter to show total number of hits on your web site. This step is also optional.

Here I’m assuming that the web container will not be restarted. If it is restarted or servlet destroyed, the hit counter will be reset.

Example

This example shows how to implement a simple page hit counter −

import java.io.*;

import java.sql.Date;

import java.util.*;

import javax.servlet.*;

import javax.servlet.http.*;




public class PageHitCounter extends HttpServlet {




   private int hitCount;




   public void init() {

      // Reset hit counter.

      hitCount = 0;

   }




   public void doGet(HttpServletRequest request, HttpServletResponse response)

      throws ServletException, IOException {




      // Set response content type

      response.setContentType("text/html");




      // This method executes whenever the servlet is hit

      // increment hitCount

      hitCount++;

      PrintWriter out = response.getWriter();

      String title = "Total Number of Hits";

      String docType = "<!doctype html public \"-//w3c//dtd html 4.0 " + "transitional//en\">\n";

     

      out.println(docType +

         "<html>\n" +

            "<head><title>" + title + "</title></head>\n" +

            "<body bgcolor = \"#f0f0f0\">\n" +

               "<h1 align = \"center\">" + title + "</h1>\n" +

               "<h2 align = \"center\">" + hitCount + "</h2>\n" +

            "</body>

         </html>"

      );

   }

  

   public void destroy() {

      // This is optional step but if you like you

      // can write hitCount value in your database.

   }

}

Now let us compile above servlet and create following entries in web.xml

<servlet>

   <servlet-name>PageHitCounter</servlet-name>

   <servlet-class>PageHitCounter</servlet-class>

</servlet>




<servlet-mapping>

   <servlet-name>PageHitCounter</servlet-name>

   <url-pattern>/PageHitCounter</url-pattern>

</servlet-mapping>

....

Now call this servlet using URL http://localhost:8080/PageHitCounter. This would increase counter by one every time this page gets refreshed and it would display following result −

Total Number of Hits

6 Hit Counter for a Website:

Many times you would be interested in knowing total number of hits on your whole website. This is also very simple in Servlet and we can achieve this using filters.

Following are the steps to be taken to implement a simple website hit counter which is based on Filter Life Cycle −

Initialize a global variable in init() method of a filter.
Increase global variable every time doFilter method is called.
If required, you can use a database table to store the value of global variable in destroy() method of filter. This value can be read inside init() method when filter would be initialized next time. This step is optional.

Here I’m assuming that the web container will not be restarted. If it is restarted or servlet destroyed, the hit counter will be reset.

Example

This example shows how to implement a simple website hit counter −

// Import required java libraries

import java.io.*;

import javax.servlet.*;

import javax.servlet.http.*;

import java.util.*;




public class SiteHitCounter implements Filter {




   private int hitCount;




   public void  init(FilterConfig config) throws ServletException {

      // Reset hit counter.

      hitCount = 0;

   }




   public void  doFilter(ServletRequest request, ServletResponse response, FilterChain chain)

      throws java.io.IOException, ServletException {




      // increase counter by one

      hitCount++;




      // Print the counter.

      System.out.println("Site visits count :"+ hitCount );




      // Pass request back down the filter chain

      chain.doFilter(request,response);

   }

  

   public void destroy() {

      // This is optional step but if you like you

      // can write hitCount value in your database.

   }

}

Now let us compile the above servlet and create the following entries in web.xml

....

<filter>

   <filter-name>SiteHitCounter</filter-name>

   <filter-class>SiteHitCounter</filter-class>

</filter>




<filter-mapping>

   <filter-name>SiteHitCounter</filter-name>

   <url-pattern>/*</url-pattern>

</filter-mapping>

....

Now call any URL like URL http://localhost:8080/. This would increase counter by one every time any page gets a hit and it would display following message in the log −

Site visits count : 1

Site visits count : 2

Site visits count : 3

Site visits count : 4

Site visits count : 5

..................

So, this brings us to the end of blog. This Tecklearn ‘Servlets – Hits Counter’ blog helps you with commonly asked questions if you are looking out for a job in Java Programming. If you wish to learn Servlets and build a career Java Programming domain, then check out our interactive, Java and JEE Training, that comes with 24*7 support to guide you throughout your learning period. Please find the link for course details:

https://www.tecklearn.com/course/java-and-jee-training/

Java and JEE Training

About the Course

Java and JEE Certification Training is designed by professionals as per the industrial requirements and demands. This training encompasses comprehensive knowledge on basic and advanced concepts of core Java & J2EE along with popular frameworks like Hibernate, Spring & SOA. In this course, you will gain expertise in concepts like Java Array, Java OOPs, Java Function, Java Loops, Java Collections, Java Thread, Java Servlet, and Web Services using industry use-cases and this will help you to become a certified Java expert.

Why Should you take Java and JEE Training?

Java developers are in great demand in the job market. With average pay going between $90,000/- to $120,000/- depending on your experience and the employers.
Used by more than 10 Million developers worldwide to develop applications for 15 Billion devices.
Java is one of the most popular programming languages in the software world. Rated #1 in TIOBE Popular programming languages index (15th Consecutive Year)

What you will Learn in this Course?

Introduction to Java

Java Fundamentals
Introduction to Java Basics
Features of Java
Various components of Java language
Benefits of Java over other programming languages
Key Benefits of Java

Installation and IDE’s for Java Programming Language

Installation of Java
Setting up of Eclipse IDE
Components of Java Program
Editors and IDEs used for Java Programming
Writing a Simple Java Program

Data Handling and Functions

Data types, Operations, Compilation process, Class files, Loops, Conditions
Using Loop Constructs
Arrays- Single Dimensional and Multi-Dimensional
Functions
Functions with Arguments

OOPS in Java: Concept of Object Orientation

Object Oriented Programming in Java
Implement classes and objects in Java
Create Class Constructors
Overload Constructors
Inheritance
Inherit Classes and create sub-classes
Implement abstract classes and methods
Use static keyword
Implement Interfaces and use it

Polymorphism, Packages and String Handling

Concept of Static and Run time Polymorphism
Function Overloading
String Handling –String Class
Java Packages

Exception Handling and Multi-Threading

Exception handling
Various Types of Exception Handling
Introduction to multi-threading in Java
Extending the thread class
Synchronizing the thread

File Handling in Java

Input Output Streams
io Package
File Handling in Java

Java Collections

Wrapper Classes and Inner Classes: Integer, Character, Boolean, Float etc
Applet Programs: How to write UI programs with Applet, Java.lang, Java.io, Java.util
Collections: ArrayList, Vector, HashSet, TreeSet, HashMap, HashTable

Java Database Connectivity (JDBC)

Introduction to SQL: Connect, Insert, Update, Delete, Select
Introduction to JDBC and Architecture of JDBC
Insert/Update/Delete/Select Operations using JDBC
Batch Processing Transaction
Management: Commit and Rollback

Java Enterprise Edition – Servlets

Introduction to J2EE
Client Server architecture
URL, Port Number, Request, Response
Need for servlets
Servlet fundamentals
Setting up a web project in Eclipse
Configuring and running the web app with servlets
GET and POST request in web application with demo
Servlet lifecycle
Servlets Continued
Session tracking and filter
Forward and include Servlet request dispatchers

Java Server Pages (JSP)

Fundamentals of Java Server Page
Writing a code using JSP
The architecture of JSP
JSP Continued
JSP elements: Scriptlets, expressions, declaration
JSP standard actions
JSP directives
Introduction to JavaBeans
ServletConfig and ServletContext
Servlet Chaining
Cookies Management
Session Management

Hibernate

Introduction to Hibernate
Introduction to ORM
ORM features
Hibernate as an ORM framework
Hibernate features
Setting up a project with Hibernate framework
Basic APIs needed to do CRUD operations with Hibernate
Hibernate Architecture

POJO (Plain Old Java Object)

POJO (Plain Old Java Object)
Persistent Objects
Lifecycle of Persistent Object

Spring

Introduction to Spring
Spring Fundamentals
Advanced Spring

Got a question for us? Please mention it in the comments section and we will get back to you.

523