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.
Parameters:
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:
java.io.IOException - if an input or output error occurs
ServletException - if the request for the HEAD could not b