Including Page Fragments
You can use a JSP directive and an action to include page fragments in a JSP page. This is a useful technique when parts of all pages in an application are the same, such as headers, footers, and navigation bars.
directive reads the content of the
specified page in the translation phase (when the JSP page is
converted into a servlet) and merges it with the original page:
<%@ include file="header.html" %>
file attribute is a
URL. If it starts with a slash, it’s a context-relative path,
interpreted relative to the URI prefix assigned for the application.
If it doesn’t start with a slash, it’s a page-relative
path, interpreted relative to the path for the page that includes the
The included file can contain only static content (such as HTML) or
it can be a regular JSP page. Its contents are merged with the page
that includes it, and the resulting page is converted into a servlet,
as described in Chapter 3. This means that all
scripting variables declared in JSP declarations, scriptlets, or
actions, such as
<jsp:useBean> or custom
actions that introduce scripting variables, are shared by the main
page and all included pages. If the main page declares a variable and
the same name is used to declare another variable in an included
page, it will result in a translation phase error, since the combined
page cannot be compiled.
happens when the file you include using
include directive is changed actually isn’t specified ...