Which Java EE 6 Annotations Should You Use for Bean Management and Dependency Injection?

Java EE 6 Bean Management: A Comprehensive Guide to @ManagedBean, @Inject, and @Named

Java EE 6 introduces a myriad of annotations for bean management and dependency injection, fostering a bit of confusion. This guide aims to unravel the complexities and establish clear usage guidelines for @javax.annotation.ManagedBean, @javax.inject.Named, @javax.faces.ManagedBean, and @javax.inject.Inject.

Understanding Bean Types in Java EE 6

Managed beans are objects whose life cycles are managed by containers. Java EE 6 features various containers managing their own bean types:

• JSF Managed Beans: Specifically designed for JSF applications, they provide a simple DI mechanism.
• CDI Beans: Introduced in Java EE 6, CDI beans boast advanced features such as dependency injection, interceptors, and conversations.
• EJBs: Transactional beans with support for remote or local access, state management, and asynchronous processing.

When to Use Each Annotation

@javax.annotation.ManagedBean

This annotation declares a bean managed by the EJB container. It is used to create managed beans for EJB applications.

@javax.inject.Named vs. @javax.faces.ManagedBean

Both annotations identify beans that can be referenced by name. @javax.inject.Named is used for CDI and EJB beans, while @javax.faces.ManagedBean is specifically for JSF beans.

@javax.inject.Inject

This annotation is used for dependency injection in CDI and EJB contexts. It injects beans into other beans, allowing them to access necessary dependencies.

Example Usage

EJB:

@Stateless
@ManagedBean
public class MyEJB {
  ...
}

CDI:

@Named("myBean")
@RequestScoped
public class MyBean {
  @Inject
  private MyService service;
  ...
}

JSF:

@ManagedBean(name="myManagedBean")
@RequestScoped
public class MyManagedBean {
  ...
}

Choosing the Right Bean

Never use @javax.faces.ManagedBean unless necessary for servlet containers without CDI support.

Use CDI beans for most scenarios, unless you require the advanced features of EJBs like transaction management or state preservation.

Use EJBs when you need to access remote or local EJBs, manage distributed transactions, and utilize advanced enterprise features.

For @ViewScoped support in CDI, consider using a compatible library like seam-faces or MyFaces CODI, or opt for @ViewAccessScoped or @ConversationScoped.

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