Dinesh on Java

Categories: Servlet

Servlets Hits Counter

This example illustrates about counting how many times the servlet is accessed. When first time servlet (CounterServlet) runs then session is created and value of the counter will be zero and after again accessing of servlet the counter value will be increased by one. In this program isNew() method is used whether session is new or old and getValue() method is used to get the value of counter.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.

Popular Tutorials

CounterServlet.java

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class CounterServlet extends HttpServlet{
  public void doGet(HttpServletRequest request, 
  HttpServletResponse response)
  throws ServletException, IOException {
  HttpSession session = request.getSession(true);
  response.setContentType("text/html");
  PrintWriter out = response.getWriter();
  Integer count = new Integer(0);
  String head;
  if (session.isNew()) {
  head = "This is the New Session";
  } else {
  head = "This is the old Session";
  Integer oldcount =(Integer)session.getValue("count"); 
  if (oldcount != null) {
  count = new Integer(oldcount.intValue() + 1);
  }
  }
  session.putValue("count", count);
  out.println("<HTML><BODY BGCOLOR="#FDF5E6">n" +
  "<H2 ALIGN="CENTER">" + head + "</H2>n" + 
  "<TABLE BORDER=1 ALIGN=CENTER>n"
  + "<TR BGCOLOR="#FFAD00">n" 
  +"  <TH>Information Type<TH>Session Countn" 
  +"<TR>n" +" <TD>Total Session Accessesn" +
  "<TD>" + count + "n" +
  "</TABLE>n" 
  +"</BODY></HTML>" );
  }
}

Mapping of Servlet (“CounterServlet.java”) in web.xml file

<servlet>
  <servlet-name>CounterServlet</servlet-name>
  <servlet-class>CounterServlet</servlet-class>
</servlet> 
<servlet-mapping>
  <servlet-name>CounterServlet</servlet-name>
  <url-pattern>/CounterServlet</url-pattern>
</servlet-mapping>

Running the servlet by this url:
http://localhost:8080/CounterServlet
displays the figure below:

When servlet is hit six times by the user the counter value will be increased by six as shown in figure below:

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ServletConfig
ServletContext
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Dinesh Rajput

Dinesh Rajput is the chief editor of a website Dineshonjava, a technical blog dedicated to the Spring and Java technologies. It has a series of articles related to Java technologies. Dinesh has been a Spring enthusiast since 2008 and is a Pivotal Certified Spring Professional, an author of a book Spring 5 Design Pattern, and a blogger. He has more than 10 years of experience with different aspects of Spring and Java design and development. His core expertise lies in the latest version of Spring Framework, Spring Boot, Spring Security, creating REST APIs, Microservice Architecture, Reactive Pattern, Spring AOP, Design Patterns, Struts, Hibernate, Web Services, Spring Batch, Cassandra, MongoDB, and Web Application Design and Architecture. He is currently working as a technology manager at a leading product and web development company. He worked as a developer and tech lead at the Bennett, Coleman & Co. Ltd and was the first developer in his previous company, Paytm. Dinesh is passionate about the latest Java technologies and loves to write technical blogs related to it. He is a very active member of the Java and Spring community on different forums. When it comes to the Spring Framework and Java, Dinesh tops the list!