tut-install/examples/web/jsf
Java Platform, Enterprise Edition (Java EE) 8 The Java EE Tutorial |
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The hello1
application is a web module that uses JavaServer Faces
technology to display a greeting and response. You can use a text editor
to view the application files, or you can use NetBeans IDE.
The source code for this application is in the
tut-install/examples/web/jsf/hello1/
directory.
The following topics are addressed here:
To view the hello1
web module using NetBeans IDE:
From the File menu, choose Open Project.
In the Open Project dialog box, navigate to:
tut-install/examples/web/jsf
Select the hello1
folder and click Open Project.
Expand the Web Pages node and double-click the index.xhtml
file to
view it in the editor.
The index.xhtml
file is the default landing page for a Facelets
application. In a typical Facelets application, web pages are created in
XHTML. For this application, the page uses simple tag markup to display
a form with a graphic image, a header, a field, and two command buttons:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html lang="en"
xmlns="http://www.w3.org/1999/xhtml"
xmlns:h="http://xmlns.jcp.org/jsf/html">
<h:head>
<title>Facelets Hello Greeting</title>
</h:head>
<h:body>
<h:form>
<h:graphicImage url="#{resource['images:duke.waving.gif']}"
alt="Duke waving his hand"/>
<h2>Hello, my name is Duke. What's yours?</h2>
<h:inputText id="username"
title="My name is: "
value="#{hello.name}"
required="true"
requiredMessage="Error: A name is required."
maxlength="25" />
<p></p>
<h:commandButton id="submit" value="Submit" action="response">
</h:commandButton>
<h:commandButton id="reset" value="Reset" type="reset">
</h:commandButton>
</h:form>
...
</h:body>
</html>
The most complex element on the page is the inputText
field. The
maxlength
attribute specifies the maximum length of the field. The
required
attribute specifies that the field must be filled out; the
requiredMessage
attribute provides the error message to be displayed
if the field is left empty. The title
attribute provides the text to
be used by screen readers for the visually disabled. Finally, the
value
attribute contains an expression that will be provided by the
Hello
managed bean.
The web page connects to the Hello
managed bean through the Expression
Language (EL) value expression #{hello.name}
, which retrieves the
value of the name
property from the managed bean. Note the use of
hello
to reference the managed bean Hello
. If no name is specified
in the @Named
annotation of the managed bean, the managed bean is
always accessed with the first letter of the class name in lowercase.
The Submit commandButton
element specifies the action as response
,
meaning that when the button is clicked, the response.xhtml
page is
displayed.
Double-click the response.xhtml
file to view it.
The response page appears. Even simpler than the greeting page, the
response page contains a graphic image, a header that displays the
expression provided by the managed bean, and a single button whose
action
element transfers you back to the index.xhtml
page:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html lang="en"
xmlns="http://www.w3.org/1999/xhtml"
xmlns:h="http://xmlns.jcp.org/jsf/html">
<h:head>
<title>Facelets Hello Response</title>
</h:head>
<h:body>
<h:form>
<h:graphicImage url="#{resource['images:duke.waving.gif']}"
alt="Duke waving his hand"/>
<h2>Hello, #{hello.name}!</h2>
<p></p>
<h:commandButton id="back" value="Back" action="index" />
</h:form>
</h:body>
</html>
Expand the Source Packages node, then the javaeetutorial.hello1
node.
Double-click the Hello.java
file to view it.
The Hello
class, called a managed bean class, provides getter and
setter methods for the name
property used in the Facelets page
expressions. By default, the expression language refers to the class
name, with the first letter in lowercase (hello.name
).
package javaeetutorial.hello1;
import javax.enterprise.context.RequestScoped;
import javax.inject.Named;
@Named
@RequestScoped
public class Hello {
private String name;
public Hello() {
}
public String getName() {
return name;
}
public void setName(String user_name) {
this.name = user_name;
}
}
If you use the default name for the bean class, you can specify @Model
as the annotation instead of having to specify both @Named
and
@RequestScoped
. The @Model
annotation is called a stereotype, a term
for an annotation that encapsulates other annotations. It is described
later in Using Stereotypes in CDI
Applications. Some examples will use @Model
where it is appropriate.
Under the Web Pages node, expand the WEB-INF node and double-click
the web.xml
file to view it.
The web.xml
file contains several elements that are required for a
Facelets application. All of the following are created automatically
when you use NetBeans IDE to create an application.
A context parameter specifying the project stage:
<context-param>
<param-name>javax.faces.PROJECT_STAGE</param-name>
<param-value>Development</param-value>
</context-param>
A context parameter provides configuration information needed by a web application. An application can define its own context parameters. In addition, JavaServer Faces technology and Java Servlet technology define context parameters that an application can use.
A servlet
element and its servlet-mapping
element specifying the
FacesServlet
. All files with the .xhtml
suffix will be matched:
<servlet>
<servlet-name>Faces Servlet</servlet-name>
<servlet-class>javax.faces.webapp.FacesServlet</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>Faces Servlet</servlet-name>
<url-pattern>*.xhtml</url-pattern>
</servlet-mapping>
A welcome-file-list
element specifying the location of the landing
page:
<welcome-file-list>
<welcome-file>index.xhtml</welcome-file>
</welcome-file-list>
In the Hello.java
class, the annotations javax.inject.Named
and
javax.enterprise.context.RequestScoped
identify the class as a managed
bean using request scope. Scope defines how application data persists
and is shared.
The most commonly used scopes in JavaServer Faces applications are the following:
Request (@RequestScoped
): Request scope persists during a single
HTTP request in a web application. In an application like hello1
, in
which the application consists of a single request and response, the
bean uses request scope.
Session (@SessionScoped
): Session scope persists across multiple
HTTP requests in a web application. When an application consists of
multiple requests and responses where data needs to be maintained, beans
use session scope.
Application (@ApplicationScoped
): Application scope persists across
all users' interactions with a web application.
For more information on scopes in JavaServer Faces technology, see Using Managed Bean Scopes.
A web module must be packaged into a WAR in certain deployment scenarios
and whenever you want to distribute the web module. You can package a
web module into a WAR file by using Maven or by using the IDE tool of
your choice. This tutorial shows you how to use NetBeans IDE or Maven to
build, package, and deploy the hello1
sample application.
You can deploy a WAR file to GlassFish Server by:
Using NetBeans IDE
Using the asadmin
command
Using the Administration Console
Copying the WAR file into the domain-dir/autodeploy/
directory
Throughout the tutorial, you will use NetBeans IDE or Maven for packaging and deploying.
To build and package the hello1
web module using NetBeans IDE:
Start GlassFish Server as described in To Start GlassFish Server Using NetBeans IDE, if you have not already done so.
From the File menu, choose Open Project.
In the Open Project dialog box, navigate to:
tut-install/examples/web/jsf
Select the hello1
folder.
Click Open Project.
In the Projects tab, right-click the hello1
project and select
Build. This command deploys the project to the server.
To build and package the hello1
web module using Maven:
Start GlassFish Server as described in To Start GlassFish Server Using the Command Line, if you have not already done so.
In a terminal window, go to:
tut-install/examples/web/jsf/hello1/
Enter the following command:
mvn install
This command spawns any necessary compilations and creates the WAR file
in tut-install/examples/web/jsf/hello1/target/
. It then deploys the
project to the server.
GlassFish Server provides two ways to view the deployed web modules: the
Administration Console and the asadmin
command. You can also use
NetBeans IDE to view deployed modules.
To view deployed web modules using the Administration Console:
Open the URL http://localhost:4848/
in a browser.
Select the Applications node.
The deployed web modules appear in the Deployed Applications table.
Enter the following command:
asadmin list-applications
Now that the web module is deployed, you can view it by opening the
application in a web browser. By default, the application is deployed to
host localhost
on port 8080. The context root of the web application
is hello1
.
To run the deployed hello1
web module:
Open a web browser.
Enter the following URL:
http://localhost:8080/hello1/
In the field, enter your name and click Submit.
The response page displays the name you submitted. Click Back to try again.
If dynamic reloading is enabled, you do not have to redeploy an
application or module when you change its code or deployment
descriptors. All you have to do is copy the changed pages or class files
into the deployment directory for the application or module. The
deployment directory for a web module named context-root is
domain-dir/applications/context-root
. The server checks for changes
periodically and redeploys the application, automatically and
dynamically, with the changes.
This capability is useful in a development environment because it allows code changes to be tested quickly. Dynamic reloading is not recommended for a production environment, however, because it may degrade performance. In addition, whenever a reload takes place, the sessions at that time become invalid, and the client must restart the session.
In GlassFish Server, dynamic reloading is enabled by default.
You can undeploy web modules and other types of enterprise applications by using either NetBeans IDE or Maven.
To undeploy the hello1
web module using NetBeans IDE:
In the Services tab, expand the Servers node, then expand the GlassFish Server node.
Expand the Applications node.
Right-click the hello1
module and select Undeploy.
To delete the class files and other build artifacts, go back to the Projects tab, right-click the project, and select Clean.
To undeploy the hello1
web module using Maven:
In a terminal window, go to:
tut-install/examples/web/jsf/hello1/
Enter the following command:
mvn cargo:undeploy
To delete the class files and other build artifacts, enter the following command:
mvn clean
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