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Language: Java
Expertise: Beginner

Feb 4, 2000

Sometimes, it is extremely useful to know the number of times a Web page is hit. This is especially so if a web site depends on usage statistics in order to determine peak access times. It is fairly simple to count the hits using a servlet. As we know, when a servlet is hit, the "public void doGet(HttpServletRequest request, HttpServletResponse response)" method of http servlet executes. This is exactly where we can update a variable that keeps count of number of web page (servlet) hits. The following code illustrates this:

 
import javax.servlet.*; 
import javax.servlet.http.*; 

public class PageHitCounter extends HttpServlet 
{ 
   private int numPageHits; 
               
   public void init() 
   { 
       //here we can read in the previous value of  numPageHits from 
       //a file or a database, or .... 
       //if there is no initial value, or we fail to read in the value, 
       //initialize numPageHits 
   } 
               
public void doGet(HttpServletRequest request, 
                             HttpServletResponse response) 
                                   throws IOException, ServletException 
{ 
   //this method executes whenever the servlet is hit 
   //increment numPageHits 
   numPageHits++; 
} 
               
public void destroy() 
{ 
   //the servlet instance is about to be destroyed 
   //write the value of numPageHits to a file, 
   //or a database, or ... 
} 

Note that by involving the init(), an destroy() method in the hit-counting process, we can provide persistence for the value of numPageHits.