com.purpletech.servlets
Class CookieDetector

java.lang.Object
  |
  +--javax.servlet.GenericServlet
        |
        +--javax.servlet.http.HttpServlet
              |
              +--com.purpletech.servlets.CookieDetector

All Implemented Interfaces:

java.io.Serializable, javax.servlet.Servlet, javax.servlet.ServletConfig

public class CookieDetector

extends javax.servlet.http.HttpServlet

This servlet detects whether the client accepts cookies. It acts as a gateway, eventually sending the user to one of two URLs. One URL results when the user has accepted the cookie; another results either if the user rejected the cookie, or if the user's browser does not support cookies. The intention is to use the "no-cookie" page as a message to the user saying "this site requires cookies -- pretty please accept my cookies or the site won't work right."

The sequence of events is:

• User invokes servlet
• Servlet drops a cookie on the client
• Servlet sends a redirect, pointing the user back to itself, with a flag saying "this is the test phase"
• The test phase detects whether
  • The client accepted the cookie
  • The client rejected the cookie (or the browser doesn't support cookies)
• Servlet sends another redirect to the destination page

Use the urlCookies and urlNoCookies init parameters to specify the destination pages for clients that accept and rejct cookies, respectively.

(It would be nice if all implementations of Session Tracking used a similar technique. As it is, some servlet engines seem to just check whether the browser can potentially support cookies, not whether a particular user has disabled cookies for this session or site.)

Download the source

See Also:

Serialized Form

Constructor Summary

CookieDetector()

Method Summary

void	doGet(javax.servlet.http.HttpServletRequest req, javax.servlet.http.HttpServletResponse res)

Methods inherited from class javax.servlet.http.HttpServlet

doDelete, doOptions, doPost, doPut, doTrace, getLastModified, service, service

Methods inherited from class javax.servlet.GenericServlet

destroy, getInitParameter, getInitParameterNames, getServletConfig, getServletContext, getServletInfo, getServletName, init, init, log, log

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

CookieDetector

public CookieDetector()

Method Detail

doGet

public void doGet(javax.servlet.http.HttpServletRequest req,
                  javax.servlet.http.HttpServletResponse res)
           throws java.io.IOException,
                  javax.servlet.ServletException

Overrides:

doGet in class javax.servlet.http.HttpServlet

java.io.IOException

javax.servlet.ServletException