Actions in JSP
The jsp:include Action
This action lets us insert files into the page being generated.
The syntax looks like this:
<jsp:include page="relative URL" flush="true" />
Unlike the include directive which inserts the file at the time the JSP page is translated into a servlet, this action inserts the file at the time the page is requested. This pays a small penalty in efficiency, and precludes the included page from containing general JSP code (it cannot set HTTP headers, for example), but it gains significantly in flexibility.
For example, here is a JSP page that inserts four different snippets into a "What's New?" Web page. Each time the headlines change, authors only need to update the four files, but can leave the main JSP page unchanged.