JBoss series seventy: A simple CDI Web applications

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Outline

Through a simple CDI Web application demos dependency injection, scope, qualifiers and EL integration. After the completion of the deployment of applications we can http: 8080 / moodchecker: // localhost to access the Web application welcome page, Mood constantly change between good and bad. In this article, we can understand how qualifiers influence the selection of an injector .

Compile deploy test applications

The present application source code is https://github.com/kylinsoong/webframework/tree/master/cdi/moodchecker .

We can use the software installation and data downloading method described download, compile, generate a deployment package cdi-moodchecker.war, use use 4 ways to deploy applications to JBoss7 / WildFly method described in the deployment cdi-moodchecker.war to JBoss node. Start JBoss 7 application deployment is completed as follows:

./standalone.sh

After the completion of the deployment of applications we can http: 8080 / moodchecker: // localhost access, Web page shown below:

Examples of analysis

Example relates to the profile or java class comprises:

beans.xml
faces-config.xml
index.xhtml
web.xml
jboss-web.xml
org.jboss.demo.cdi.moodchecker.Mood
org.jboss.demo.cdi.moodchecker.BadMood
org.jboss.demo.cdi.moodchecker.GoodMood
org.jboss.demo.cdi.moodchecker.MoodChecker

Mood

Mood categories as follows:

import javax.enterprise.context.RequestScoped;
import javax.inject.Inject;
import javax.inject.Named;

@Named
@RequestScoped
public class Mood {

	private String mood;
	
	@Inject
	@Good
	private MoodChecker moodChecker;

	public Mood() {

	}

	public void check() {
		mood = moodChecker.checkMood();
	}

	public String getMood() {
		return mood;
	}
}

Note: @Named and @RequestScoped label class itself, MoodChecker properties and use @Inject @Good injection.

Qualifiers

Note that in front of Good is our custom label for injecting GoodMood, we have created here two tagging, Good and Bad, as follows:

import java.lang.annotation.Documented;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;

import javax.inject.Qualifier;

import static java.lang.annotation.ElementType.FIELD;
import static java.lang.annotation.ElementType.METHOD;
import static java.lang.annotation.ElementType.PARAMETER;
import static java.lang.annotation.ElementType.TYPE;
import static java.lang.annotation.RetentionPolicy.RUNTIME;

@Qualifier
@Target({ TYPE, METHOD, PARAMETER, FIELD })
@Retention(RUNTIME)
@Documented
public @interface Good {

}

We use the Good mark GoodMood, as follows:

@Good
public class GoodMood implements MoodChecker {

	public String checkMood() {
		return "I feel great !";
	}

}

Thus when using @Good labels will Mood injection GoodMood.

EL integration

Mood index.xhtml use EL expressions to interact directly with back-Bean, index.xhtml reads as follows:

<!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:h="http://java.sun.com/jsf/html"
	xmlns:f="http://java.sun.com/jsf/core">

<h:head>
	<title>How Are You Today?</title>
</h:head>
<h:body>
	<h3>How Are You?</h3>
	<h:form>
		<p>
			<h:commandButton value="Check Mood" action="#{mood.check}" />
		</p>
		<p>
			<h:outputText value="#{mood.mood}" />
		</p>

	</h:form>
</h:body>

</html>

Reproduced in: https: //my.oschina.net/iwuyang/blog/197250