JSF – Eager CDI beans

Everybody knows eager managed beans in JSF 2. @ManagedBean has an eager attribute. If eager=’true’ and the scope is application, then this bean must be created when the application starts and not during the first reference to the bean. This is a nice feature when you want to load application scoped data (e.g. some select items for menus) during application startup in order to increase the performance at runtime.
 
 
 
 
 
 

@ManagedBean(eager=true)
@ApplicationScoped
public class GlobalBean {
    ...
}

@ManagedBean annotation will be deprecated with JSF 2.2. It is highly recommended to use CDI (context dependency injection) beans in JEE environment. But what is the equivalent to the eager managed beans in CDI? Well, CDI is flexible, you can write portable CDI extensions. I asked Thomas Andraschko how to do this. Thomas is a CDI expert, co-owner of PrimeFaces Extensions and the committer in OpenWebBeans (OWB) project. His tip was to implement such extension as follows:

@Qualifier
@Retention(RetentionPolicy.RUNTIME)
@Target({TYPE})
public @interface Eager
{
}
package mydomain.mypackage;

import java.util.ArrayList;
import java.util.List;
import javax.enterprise.context.ApplicationScoped;
import javax.enterprise.event.Observes;
import javax.enterprise.inject.spi.AfterDeploymentValidation;
import javax.enterprise.inject.spi.Bean;
import javax.enterprise.inject.spi.BeanManager;
import javax.enterprise.inject.spi.Extension;
import javax.enterprise.inject.spi.ProcessBean;

public class EagerExtension implements Extension {
    private List<Bean<?>> eagerBeansList = new ArrayList<Bean<?>>();

    public <T> void collect(@Observes ProcessBean<T> event) {
        if (event.getAnnotated().isAnnotationPresent(Eager.class)
            && event.getAnnotated().isAnnotationPresent(ApplicationScoped.class)) {
            eagerBeansList.add(event.getBean());
        }
    }

    public void load(@Observes AfterDeploymentValidation event, BeanManager beanManager) {
        for (Bean<?> bean : eagerBeansList) {
            // note: toString() is important to instantiate the bean
            beanManager.getReference(bean, bean.getBeanClass(), beanManager.createCreationalContext(bean)).toString();
        }
    }
}

The extensions should be registered in a file META-INF/services/javax.enterprise.inject.spi.Extension. The file has only one line with a fully qualified path to the EagerExtension class, e.g. mydomain.mypackage.EagerExtension. Using is simple. Assume, we have an application scoped LayoutController CDI bean which is responsible for the entire layout configration. We can annotate it with @Eager and speed up the layout creation.

@ApplicationScoped
@Eager
@Named
public class LayoutController implements Serializable {
    private LayoutOptions layoutOptions;

    @PostConstruct
    protected void initialize() {
        layoutOptions = new LayoutOptions();

        LayoutOptions panes = new LayoutOptions();
        panes.addOption('slidable', false);
        panes.addOption('spacing', 6);
        layoutOptions.setPanesOptions(panes);

        ...
    }

    public LayoutOptions getLayoutOptions() {
        return layoutOptions;
    }
}

Have fun with CDI!
 

Reference: JSF – Eager CDI beans from our JCG partner Oleg Varaksin at the Thoughts on software development blog.

Related Whitepaper:

Functional Programming in Java: Harnessing the Power of Java 8 Lambda Expressions

Get ready to program in a whole new way!

Functional Programming in Java will help you quickly get on top of the new, essential Java 8 language features and the functional style that will change and improve your code. This short, targeted book will help you make the paradigm shift from the old imperative way to a less error-prone, more elegant, and concise coding style that’s also a breeze to parallelize. You’ll explore the syntax and semantics of lambda expressions, method and constructor references, and functional interfaces. You’ll design and write applications better using the new standards in Java 8 and the JDK.

Get it Now!  

3 Responses to "JSF – Eager CDI beans"

  1. Bill B. says:

    In NetBeans 7.3, your code:

    @Qualifier
    @Retention(RetentionPolicy.RUNTIME)
    @Target({TYPE})
    public @interface Eager
    {
    }

    Causes the following error:

    The CDI Annotation is declared as Qualifier but it has wrong target values. Correct target values are ‘{METHOD, FIELD, PARAMETER, TYPE’} or ‘{FIELD, PARAMETER’}.

    Anybody got a fix or a work-around?

    Thanks, Bill

  2. tdr says:

    Hi this was a very informative article. I’ve never dealt with extensions before. I”m just now becoming familar with CDI. I followed these instructions exactly — I’m building a Map to be used as a select list in a search page and I want it initialized while the app is being deployed. I’d previously implemented it as an eager=true @ManagedBean before I switched from JSF2 to CDI.
    I’m getting this error now during deployment
    WELD-001408 Unsatisfied dependencies for type [StateList] with qualifiers [@Default] at injection point [[field] @Inject gov.ssa.dne.nmst.view.Search.stateList]
    I can’t understand which unsatisfied dependencies it’s refering to.

  3. Pete says:

    I followed the code to the letter but the Collect method is not scanning my classes. It does scan something like 53 classes in org.jboss.weld.bean and in com.sun.jersey.server.impl.cdi. I tried everything I could think of to no avail. I’m stuck… Any suggestions?

Leave a Reply


3 × five =



Java Code Geeks and all content copyright © 2010-2014, Exelixis Media Ltd | Terms of Use | Privacy Policy
All trademarks and registered trademarks appearing on Java Code Geeks are the property of their respective owners.
Java is a trademark or registered trademark of Oracle Corporation in the United States and other countries.
Java Code Geeks is not connected to Oracle Corporation and is not sponsored by Oracle Corporation.

Sign up for our Newsletter

20,709 insiders are already enjoying weekly updates and complimentary whitepapers! Join them now to gain exclusive access to the latest news in the Java world, as well as insights about Android, Scala, Groovy and other related technologies.

As an extra bonus, by joining you will get our brand new e-books, published by Java Code Geeks and their JCG partners for your reading pleasure! Enter your info and stay on top of things,

  • Fresh trends
  • Cases and examples
  • Research and insights
  • Two complimentary e-books