my dog learned polymorphism
The moose likes Web Component Certification (SCWCD/OCPJWCD) and the fly likes doHead method Big Moose Saloon
  Search | Java FAQ | Recent Topics | Flagged Topics | Hot Topics | Zero Replies
Register / Login
JavaRanch » Java Forums » Certification » Web Component Certification (SCWCD/OCPJWCD)
Bookmark "doHead method" Watch "doHead method" New topic

doHead method

Amit Ghag

Joined: May 11, 2002
Posts: 27
As per Servlet 2.3 specifications, there is a doHead method to handle the Head request. However, the book Java Servlet Programming states that when a doHead method is requested, the service method modifies the response object to suppress the body content and forwards the reqest to doGet method. Any ideas on this one ?

R K Singh
Ranch Hand

Joined: Oct 15, 2001
Posts: 5382
in servlet2.2 there was no doHead() method. I think you are using old book.
In servlet2.3 there is doHead() method also.
========== from API ===========
protected void doHead(HttpServletRequest req,
HttpServletResponse resp)
throws ServletException,
Receives an HTTP HEAD request from the protected service method and handles the request. The client sends a HEAD request when it wants to see only the headers of a response, such as Content-Type or Content-Length. The HTTP HEAD method counts the output bytes in the response to set the Content-Length header accurately.
If you override this method, you can avoid computing the response body and just set the response headers directly to improve performance. Make sure that the doHead method you write is both safe and idempotent (that is, protects itself from being called multiple times for one HTTP HEAD request).
If the HTTP HEAD request is incorrectly formatted, doHead returns an HTTP "Bad Request" message.
req - the request object that is passed to the servlet
resp - the response object that the servlet uses to return the headers to the clien
Throws: - if an input or output error occurs
ServletException - if the request for the HEAD could not be handled
[ June 19, 2002: Message edited by: Ravish Kumar ]

"Thanks to Indian media who has over the period of time swiped out intellectual taste from mass Indian population." - Chetan Parekh
I agree. Here's the link:
subject: doHead method
It's not a secret anymore!