Very Very Urgent...Need Code for Calculating Execution Time For Jsp Page

Generally the first rule here is, we aren't going to do your work for you, we will however help you if you are making an effort.

And second: asking for preferential treatment by claiming you need something urgently (or "by noon and it's already 10AM") will be counterproductive.

Now for your question (12 hours sounds like a decent penalty :) ):
The simplest way would be to insert some logging statements at the beginning and end of your JSP.
JSPs are executed in linear fashion by the application server (effectively your JSP becomes the body of the service method of a servlet) so that would give you a timestamp for start and end of execution.

What it won't do is give you the complete execution time of the request, as that includes time taken by the application server, network latency and transmission times, rendering time by the browser, etc..
Those you can't really find out about and you can't control them, except the browser rendering which depends in large part on the complexity and size of the generated HTML code (as an example, we were able to bring the rendering time on one particularly complex page here back from 10 seconds to under 3 by making some minor changes to the html).
Tomcat of course should also be able to be configured to log every request and response with a timestamp, up to you to figure out.

ya, usually, it takes FEW MONTHS to have a few reply from daniweb.com

Unless you offer Materialistic goods shipped from amzon.com, you won't get a quick answer

ya, usually, it takes FEW MONTHS to have a few reply from daniweb.com

Unless you offer Materialistic goods shipped from amzon.com, you won't get a quick answer

So you drug up a two-year-old thread to post this inane and utterly inaccurate comment? Brilliant.