Templating

JavaServer Faces 2.0 provides the tools to implement user interfaces that are easy to extend and reuse. Templating is a useful feature available with Facelets that allows you to create a page that will act as the base or template for the other pages in a application. By using templates, you can reuse code and avoid recreating similarly constructed pages. Templating also helps in maintaining a standard look and feel in an application with a large number of pages.

The following table lists Facelets tags that are used for templating and their respective functionality:

Table 5-2 Facelets Templating Tags

Tag	Function
`ui:component`	Defines a component that is created and added to the component tree.
`ui:composition`	Defines a page composition that optionally uses a template. Content outside of this tag is ignored.
`ui:debug`	Defines a debug component that is created and added to the component tree.
`ui:define`	Defines content that is inserted into a page by a template
`ui:decorate`	Similar to composition tag but does not disregard content outside this tag.
`ui:fragment`	Similar to component tag but does not disregard content outside this tag.
`ui:include`	Encapsulate and reuse content for multiple pages.
`ui:insert`	Inserts content into a template.
`ui:param`	Used to pass parameters to an included file.
`ui:repeat`	Used as an alternative for loop tags such as `c:forEach` or `h:dataTable.`
`ui:remove`	Removes content from a page.

For more information on Facelets templating tags, see the PDL athttp://java.sun.com/javaee/javaserverfaces/2.0/docs/pdldocs/facelets/index.html.

The Facelets tag library includes the main templating tag <ui:insert>. Atemplate page is created with this tag, it allows defining a default structure for a page. A template page can be reused as a template for other pages, usually referred to as a client pages.

Here is an example of a template saved as template.xhtml:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
      xmlns:ui="http://java.sun.com/jsf/facelets"
      xmlns:h="http://java.sun.com/jsf/html">
    
    <h:head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
        <link href="./resources/css/default.css" rel="stylesheet" type="text/css" />
        <link href="./resources/css/cssLayout.css" rel="stylesheet" type="text/css" />
        <title>Facelets Template</title>
    </h:head>
    
    <h:body>
        <div id="top" class="top">
            <ui:insert name="top">Top Section</ui:insert>
        </div>
        <div>
        <div id="left">
             <ui:insert name="left">Left Section</ui:insert>
        </div>
        <div id="content" class="left_content">
             <ui:insert name="content">Main Content</ui:insert>
        </div>
        </div>
    </h:body>
    
</html>

The example page defines a HTML page that is divided into 3 sections, a top section, a left section and a main section. The sections have stylesheets associated with them. The same structure can be reused for the other pages of the application.

The client page invokes the template by using <ui:composition> tag. In the following example, a client page named templateclient.xhtml, invokes the template page from the preceding example named template.xhtml. A client page allows content to be inserted with the help of the <ui:define> tag.

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
      xmlns:ui="http://java.sun.com/jsf/facelets"
      xmlns:h="http://java.sun.com/jsf/html">
    
    <h:body>
        
        <ui:composition template="./template.xhtml">
            <ui:define name="top">
                Welcome to Template Client Page
            </ui:define>

            <ui:define name="left">
                <h:outputLabel value="You are in the Left Section"/>
                               
            </ui:define>

            <ui:define name="content">
                <h:graphicImage value="#{resource['images:wave.med.gif']}"/>
                <h:outputText value="You are in the Main Content Section"/>
            </ui:define>

        </ui:composition>
        
    </h:body>
</html>

You can use the NetBeans IDE to create Facelets template and client pages. For more information on creating these pages, see http://netbeans.org/kb/docs/web/jsf20-intro.html.