Here is my code:
<base href="http://server_A/">
<
jsp:include page="/html/page1"/>
<base href="http://<%= req.getServerName() %>"/>
<FORM action=/app/submit" method="POST">
..
</FORM>
I found that ---
If I directly hit "continue" button to go to next page, the next page gets the same session id as the first page; but if I hit "refresh" button on this 1st page, then the next JSP page will get a different session ID, but this only happens once, after that the next page always gets that session id and won't change any more.