In the first of many posts regarding the recently finalized JSF 2.0, I will be showing you what you need to do to write a simple Hello World Application. Instead of traditional JSF backing beans, this application will use Weld, an open-source implementation of JSR-299: Contexts and Dependency Injection for the Java EE platform. JSR-299 will be part of the upcoming JEE 6 specification.
Prerequisites:
Install Sun’s JDK 6, the latest version of Maven (presently 2.2.1), and the IDE of your choice. I use Eclipse, but GEdit or notepad would work just fine. For this demo, I’ll be using Jetty, so you won’t need to install a container of any sort.
Getting Started:
Create Empty Project
Our first step is to create an ordinary empty WAR project in Maven using the
archetype:generate
command in the directory of your choice.
cd ~/workspace #this can obviously be anywhere.
mvn archetype:generate -DinteractiveMode=n -DarchetypeArtifactId=maven-archetype-webapp -Dversion=0.0.1-SNAPSHOT -DgroupId=org.bogus -DartifactId=jsf2_tutorial
Unfortunately, the default Maven archetype falls short of what we need, so we need to make a few extra directories. We need a java directory and the test java and resources directory. I’ve also added the commands that an eclipse user would use to generate an importable eclipse project. Netbeans and IntellJ users can simply import the pom.xml.
#create a few extra directories for the project.
mkdir jsf2_tutorial/src/test jsf2_tutorial/src/test/java jsf2_tutorial/src/test/resources jsf2_tutorial/src/main/java
cd jsf2_tutorial
#if you're using *NIX, you can create empty files with this command.
mkdir src/main/java/org/ src/main/java/org/bogus/ #need to create package first.
touch pom.xml src/main/webapp/WEB-INF/web.xml src/main/webapp/WEB-INF/beans.xml src/main/java/org/bogus/HelloWorld.java src/main/webapp/index.xhtml src/test/resources/jetty-env.xml
Overview
I was very impressed that a simple Hello World project can be created with as little as five artifacts.
- /pom.xml
- /src/main/webapp/WEB-INF/web.xml
- /src/main/webapp/WEB-INF/beans.xml
- /src/main/java/org/bogus/HelloWorld.java
- /src/main/webapp/index.xhtml
- /src/test/resources/jetty-env.xml (for Jetty users).
Writing the actual Code
pom.xml
The first step is to the pom.xml file. Afterwards it can be easily imported into any modern IDE.
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>org.bogus</groupId>
<artifactId>helloworld</artifactId>
<packaging>war</packaging>
<version>0.0.1-SNAPSHOT</version>
<name>JSF 2.0 Tutorial</name>
<repositories>
<!-- As of October 2009, a few of the weld dependencies were not yet on the main maven repo. We can add JBoss repo as it is updated more frequently. -->
<repository>
<id>repository.jboss.org</id>
<name>JBoss Repository</name>
<url>http://repository.jboss.org/maven2</url>
<releases>
<enabled>true</enabled>
</releases>
<snapshots>
<enabled>false</enabled>
</snapshots>
</repository>
</repositories>
<dependencies>
<!-- Common -->
<dependency>
<groupId>javax.enterprise</groupId>
<artifactId>cdi-api</artifactId>
<scope>provided</scope>
<version>1.0-CR1</version>
</dependency>
<dependency>
<groupId>javax.annotation</groupId>
<artifactId>jsr250-api</artifactId>
<version>1.0</version>
</dependency>
<dependency>
<groupId>javax.faces</groupId>
<artifactId>jsf-api</artifactId>
<version>2.0.0-RC</version>
</dependency>
<!-- Jetty-specific scopes and artifacts -->
<dependency>
<groupId>javax.faces</groupId>
<artifactId>jsf-impl</artifactId>
<scope>runtime</scope>
<version>2.0.0-RC</version>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>jstl</artifactId>
<version>1.2</version>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.jboss.weld.servlet</groupId>
<artifactId>weld-servlet</artifactId>
<version>1.0.0-CR1</version>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.glassfish.web</groupId>
<artifactId>el-impl</artifactId>
<version>2.1.2-b04</version>
<scope>runtime</scope>
<exclusions>
<exclusion>
<groupId>javax.el</groupId>
<artifactId>el-api</artifactId>
</exclusion>
</exclusions>
</dependency>
</dependencies>
<build>
<finalName>jsf2</finalName>
<plugins>
<!-- Compiler plugin enforces Java 1.6 -->
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>1.6</source>
<target>1.6</target>
</configuration>
</plugin>
<!-- Eclipse plugin enforces download of source and JavaDoc jars -->
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-eclipse-plugin</artifactId>
<configuration>
<wtpversion>2.0</wtpversion>
<downloadSources>true</downloadSources>
<downloadJavadocs>true</downloadJavadocs>
</configuration>
</plugin>
<!-- Embedded Jetty (jetty:run) -->
<plugin>
<groupId>org.mortbay.jetty</groupId>
<artifactId>maven-jetty-plugin</artifactId>
<configuration>
<!-- force friendly name instead of artifact name + version -->
<contextPath>${build.finalName}</contextPath>
<!-- Where the BeanManager is constructed. This is where we'll later declare datasource. -->
<jettyEnvXml>${basedir}/src/test/resources/jetty-env.xml</jettyEnvXml>
<!-- This parameter will auto-deploy modified classes...my personal favorite Jetty feature. -->
<scanIntervalSeconds>3</scanIntervalSeconds>
</configuration>
</plugin>
</plugins>
</build>
</project>Now that your pom is complete, you can import it into the IDE of your choice. Eclipse requires users to either install m2eclipse or run:
Boilerplate
web.xml
Since JSF 1.2, the web.xml page got a lot smaller. This is where convention over configuration pays off. Also, faces-config.xml is now optional!
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5">
<!-- Standard JSF 2.0 Configuration Paramters. -->
<!-- No Joke!!...This is all you need now! -->
<context-param>
<param-name>javax.faces.DEFAULT_SUFFIX</param-name>
<param-value>.xhtml</param-value>
</context-param>
<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>*.jsf</url-pattern>
</servlet-mapping>
<!-- Weld Jetty Configuration parameters -->
<listener>
<listener-class>org.jboss.weld.environment.servlet.Listener</listener-class>
</listener>
<resource-env-ref>
<description>Object factory for the CDI Bean Manager</description>
<resource-env-ref-name>BeanManager</resource-env-ref-name>
<resource-env-ref-type>javax.enterprise.inject.spi.BeanManager</resource-env-ref-type>
</resource-env-ref>
</web-app>
beans.xml
In order to indicate to weld to initialize dependency injection, you’ll need to create an empty file named beans.xml. The mere presence of this file in your WEB-INF folder tells the container that your WEB-INF/classes folder is a bean deployment archive.
Application-Specific Code
HelloWorld.java
To confirm that Weld (A.K.A. JSR 299 or WebBeans) Dependency Injection works, we’re going to write an incredibly simple bean. In contrast to Spring, you don’t need to declare the package or bean. Simply adding the @Named annotations and declaring a scope is all that is needed to have your bean registered with the dependency injection container and visible to your facelets view pages.
package org.bogus;
import java.io.Serializable;
import javax.enterprise.context.SessionScoped;
import javax.inject.Named;
@Named //assigns this bean the name of "helloWorld"...its "de-caplitalized" class name
@SessionScoped //creates one bean for each user session.
public class HelloWorld implements Serializable {
private final String text = "Hello World!";
public String getText() {
return text;
}
private static final long serialVersionUID = 1L;
}index.xhtml
Now we want to actually view the bean we created. Below is an incredibly simple xhtml/facelets page.
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xmlns:h="http://java.sun.com/jsf/html">
<h:head>
<title>JSF Demo</title>
</h:head>
<h:body>
<h1>Does Weld Work?</h1>
<!-- Your bean can be easily accessed via Expression Language -->
<p>My weld-injected bean says: #{helloWorld.text}</p>
</h:body>
</html>jetty-env.xml
Since we’re not using a full JEE container, we need to configure Jetty to prepare the BeanManager.
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE Configure PUBLIC "-//Mort Bay Consulting//DTD Configure//EN"
"http://jetty.mortbay.org/configure.dtd">
<Configure id="webAppCtx" class="org.mortbay.jetty.webapp.WebAppContext">
<New id="appManager" class="org.mortbay.jetty.plus.naming.Resource">
<Arg>
<Ref id="webAppCtx" />
</Arg>
<Arg>BeanManager</Arg>
<Arg>
<New class="javax.naming.Reference">
<Arg>javax.enterprise.inject.spi.BeanManager</Arg>
<Arg>org.jboss.weld.resources.ManagerObjectFactory</Arg>
<Arg />
</New>
</Arg>
</New>
</Configure>
Start up Jetty
Jetty is an embedded servlet container that can be easily launched from Maven. Since we added that small snippet to the pom, we can simply type:
mvn war:inplace jetty:run
…and maven will download Jetty and run it with the configuration file we passed.
Test Your Application
Simply load http://localhost:8080/jsf/index.jsf
firefox http://localhost:8080/jsf/index.jsf
If you see the hello world text, everything has worked. Now that you’ve confirmed your configuration is setup correctly, you can explore the more interesting features of Weld and JSF 2, which I’ll be covering in future posts.
Download the Code
The source code to this tutorial is available via subversion here
UPDATE: Tomcat Users
With the addition of a context.xml, this example runs perfectly on Tomcat.
Please see this article for details.
Further Reading
Many thanks to the JBoss staff on the forums who helped me get started in Weld. The artifacts in this article were modeled after their examples.
