Mega Code Archive
Servlet Static Field As Counter
<![CDATA[
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.util.*;
public class MyServlet extends HttpServlet {
static int classCount = 0; // shared by all instances
int count = 0; // separate for each servlet
static Hashtable instances = new Hashtable(); // also shared
public void doGet(HttpServletRequest req, HttpServletResponse res)
throws ServletException, IOException {
res.setContentType("text/plain");
PrintWriter out = res.getWriter();
count++;
out.println("Since loading, this servlet instance has been accessed " + count + " times.");
// Keep track of the instance count by putting a reference to this
// instance in a Hashtable. Duplicate entries are ignored.
// The size() method returns the number of unique instances stored.
instances.put(this, this);
out.println("There are currently " +instances.size() + " instances.");
classCount++;
out.println("Across all instances, this servlet class has been " +
"accessed " + classCount + " times.");
}
}
<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE web-app
PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.2//EN"
"http://java.sun.com/j2ee/dtds/web-app_2_2.dtd">
<web-app>
<servlet><servlet-name>MyServletName</servlet-name>
<servlet-class>MyServlet</servlet-class>
</servlet>
<servlet-mapping><servlet-name>MyServletName</servlet-name>
<url-pattern>/index.html</url-pattern>
</servlet-mapping>
</web-app>
]]>