The Java EE 6 Tutorial, Volume I

Chapter 4 JavaServerTM Faces Technology

JavaServer Faces technology is a server-side component framework for building Java technology-based web applications.

JavaServer Faces technology consists of the following:

JavaServer Faces technology provides a well-defined programming model and various tag libraries. These features significantly ease the burden of building and maintaining web applications with server-side UIs. With minimal effort, you can complete the following tasks:

This chapter provides an overview of JavaServer Faces technology. After explaining what a JavaServer Faces application is and going over some of the primary benefits of using JavaServer Faces technology, it describes the process of creating a simple JavaServer Faces application. This chapter also introduces the JavaServer Faces lifecycle by describing the example JavaServer Faces application progressing through the lifecycle stages.

The following topics are addressed here:

What Is a JavaServer Faces Application?

The functionality provided by a JavaServer Faces application is similar to that of any other Java web application. A typical JavaServer Faces application includes the following parts:

Figure 4–1 describes the interaction between client and server in a typical JavaServer Faces application. In response to a client request, a web page is rendered by the web container that implements JavaServer Faces technology.

Figure 4–1 Responding to a Client Request for a JavaServer Faces Page

Diagram shows a browser accessing myfacelet.xhtml page
using an HTTP Request and the server sending the rendered the HTML page using
an HTTP Response.

The web page, myfacelet.xhtml, is built using JavaServer Faces component tags. Component tags are used to add components to the view (represented by myUI in the diagram), which is the server-side representation of the page. In addition to components, the web page can also reference objects such as the following:

On request from the client, the view is rendered as a response. Rendering is the process whereby, based on the server-side view, the web container generates output such as HTML or XHTML that can be read by the browser.

JavaServer Faces Technology Benefits

One of the greatest advantages of JavaServer Faces technology is that it offers a clean separation between behavior and presentation for web applications.

A JavaServer Faces application can map HTTP requests to component-specific event handling and manage components as stateful objects on the server. JavaServer Faces technology allows you to build web applications that implement the finer-grained separation of behavior and presentation that is traditionally offered by client-side UI architectures.

The separation of logic from presentation also allows each member of a web application development team to focus on a single piece of the development process, and it provides a simple programming model to link the pieces. For example, page authors with no programming expertise can use JavaServer Faces technology tags in a web page to link to server-side objects without writing any scripts.

Another important goal of JavaServer Faces technology is to leverage familiar component and web-tier concepts without limiting you to a particular scripting technology or markup language. JavaServer Faces technology APIs are layered directly on top of the Servlet API, as shown in the following diagram.

Figure 4–2 Java Web Application Technologies

Diagram of web application technologies. JavaServer Pages,
the JSP Standard Tag Library, and JavaServer Faces rest on JavaServlet technology.

This layering of APIs enables several important application use cases, such as using different presentation technologies, creating your own custom components directly from the component classes, and generating output for various client devices.

Facelets technology, available as part of JavaServer Faces 2.0, is now the preferred presentation technology for building JavaServer Faces based web applications and offers several advantages.

Facelets technology offers the advantages of code reuse and extensibility for components through Templating and Composite Components features.

When you use the JavaServer Faces Annotations feature, you can automatically register the backing bean as a resource available for JavaServer Faces applications. In addition, implicit navigation rules allow the developers to quickly configure page navigation. These features reduce the manual configuration process for applications.

For more information on Facelets technology features, see Chapter 5, Introduction to Facelets.

Most importantly, JavaServer Faces technology provides a rich architecture for managing component state, processing component data, validating user input, and handling events.

Creating a Simple JavaServer Faces Application

JavaServer Faces technology provides an easy and user-friendly process for creating web applications.

Developing a simple JavaServer Faces application typically requires the following tasks:

In this section, the above tasks are described through the process of creating a simple JavaServer Faces Facelets application.

The example is a Hello application which includes a backing bean and a web page. When accessed by a client, the web page prints out a Hello World message. The example application is located in tut-install/examples/web/hello directory.

The tasks involved in developing this application can be examined by looking at the application in detail.

Developing Backing Beans

As mentioned earlier in this chapter, a backing bean (a type of managed bean) is a JavaBean that is managed by JavaServer Faces. Components in a page are associated with backing beans which provide application logic. The example backing bean,, contains the following code:

package Hello;

import javax.faces.bean.ManagedBean;

public class Hello{
final String world = "Hello World!";

public String getWorld() 
{ return world; }


The example backing bean sets the value of the world variable with the string Hello World!. The @ManagedBean annotation registers the backing bean as a resource with the JavaServer Faces implementation. For more information on managed beans and annotations, see Developing With JavaServerTM Faces Technology.

Creating the Web Page

In a typical Facelets application, web pages are created in XHTML. The example web page, beanhello.xhtml, is a simple XHTML page. It contains the following content:

<html xmlns="">
       <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/>
       <title>JavaServer Faces Hello World Application</title>

A Facelets XHTML web page can also contain several other elements which are covered later in this tutorial.

The web page connects to the backing bean through the Unified Expression Language (EL) value expression #{}, which retrieves the value of the world property from the backing bean Hello. Note the use of hello to reference the backing bean Hello. If no name is specified in the @ManagedBean annotation, the backing bean is always accessed with the first letter of the class name in lowercase.

For more information on using EL expressions, see Chapter 6, Unified Expression Language. For more information about Facelets technology, see Introduction to Facelets. For more information about JavaServer Faces programming model and building web pages using JavaServer Faces technology, see Chapter 7, Using JavaServerTM Faces Technology in Web Pages.

Mapping the Faces Servlet Instance

The final task requires mapping the Faces Servlet which is done through the web deployment descriptor (web.xml). A typical mapping of Faces Servlet is as follows:

    <servlet-name>Faces Servlet</servlet-name>
    <servlet-name>Faces Servlet</servlet-name>

The above file segment represents part of a typical JavaServer Faces web deployment descriptor. The web deployment descriptor can also contain other content relevant to a JavaServer Faces application configuration but that information is not covered here.

Mapping the Faces Servlet is automatically done for you when using a Java EE 6server such as Sun GlassFishTM Enterprise Server v3.

The Lifecycle of the helloWorld Application

Every web application has a lifecycle. Common tasks such as handling incoming requests, decoding parameters, modifying and saving state, and rendering web pages to the browser are all performed during a web application lifecycle. Some web application frameworks hide the details of the lifecycle from you while others require you to manage them manually.

By default, JavaServer Faces handles most of the lifecycle actions for you automatically. But it does expose the different parts of the request lifecycle, so that you can modify or perform different actions if your application requirements warrant it.

It is not necessary for the beginning user to understand the lifecycle of a JavaServer Faces application, but the information can be useful for creating more complex applications.

The lifecycle of a JavaServer Faces application starts and ends with the following activity: The client makes a request for the web page, and the server responds with the page. The lifecycle consists of two main phases: execute and render.

During the execute phase, several actions can take place: The application view is built or restored, the request parameter values are applied, conversions and validations are performed for component values, backing beans are updated with component values, and application logic is invoked. For a first (initial) request, only the view is built. For subsequent (postback) requests, some or all of the other actions can take place.

In the render phase, the requested view is rendered as response to the client. Rendering, typically is the process of generating output such as HTML or XHTML that can be read by the client (usually a browser).

The following short description of the example JavaServer Faces application passing through its lifecycle summarizes the activity that takes place behind the scenes.

The helloWorld example application goes through the following stages when it is deployed on the Enterprise Server:

  1. When the helloWorld application is built and deployed on the Enterprise Server, the application is at an uninitiated state.

  2. When a client makes a first (initial) request for the beanhello.xhtml web page, the helloWorld Facelets application is compiled.

  3. The compiled Facelets application is executed and a new component tree (UIViewRoot) is constructed for the helloWorld application and is placed in the Faces Context.

  4. The component tree is populated with the component and the backing bean property associated with it (represented by the EL expression

  5. A new view is built based on the component tree.

  6. The view is rendered to the requesting client as a response.

  7. The component tree is destroyed automatically.

  8. On subsequent (postback) requests, the component tree is rebuilt and the saved state is applied.

For more detailed information on the JavaServer Faces lifecycle, see the JavaServer Faces Specification, Version 2.0 document.

ProcedureRunning the Application in NetBeans IDE

To build, package, deploy, and run the JavaServer Faces helloWorld example using NetBeans IDE, follow these steps:

  1. In NetBeans IDE, select File->Open Project.

  2. In the Open Project dialog box, navigate to the example directory:

  3. Select the helloWorld folder.

  4. Select the Open as Main Project check box.

  5. Click Open Project.

  6. In the Projects tab, right-click the helloWorld project and select Run.

    This step compiles, assembles, and deploys the application, then brings up a web browser window displaying the following URL:


Example 4–1 Example Output of the helloWorld Application

Hello World!

Further Information about JavaServer Faces Technology

For more information on JavaServer Faces technology, see: