Reusable Layouts - Stripes...and Java Web Development is Fun Again - page 148

<jsp:include page="${url}"/>

Action Bean
MenuViewHelper

result

menu.jsp

Figure 7.4: Using a view helper

That's exactly what we need:

Download email_16/web/WEB-INF/jsp/common/layout_menu.jsp
<s:layout-component name="menu">
<s:url var="url" beanclass="stripesbook.action.MenuViewHelper"
prependContext="false">
<s:param name="currentSection" value="${currentSection}"/>
</s:url>
<jsp:include page="${url}"/>
</s:layout-component>

The URL is bound to the MenuViewHelper action bean. Its default event
handler forwards to menu.jsp , which displays the menu. The result is
put back in place of the <jsp:include> tag, as illustrated in Figure 7.4 .

Notice that we have to use a URL in the <jsp:include> tag because it's a
JSP tag, not a Stripes tag. But we can still continue to use action bean
class names instead of URLs. The <s:url> tag constructs the URL for
an action bean and stores it in a variable. We can then pass the value
to the <jsp:include> tag.

The prependContext= "false" attribute is necessary because <s:url>
prepends the application context to the URL by default, and the URL
passed to the

<jsp:include> tag should not include the application

context.

With <jsp:useBean>, <s:useActionBean>, and the <s:url>/
<jsp:include>/action bean/JSP combination, we have powerful ways
of providing view helpers and building dynamic reusable layouts.