Jakub is a Java EE developer since 2005 and occasionally a project manager, working currently with Iterate AS. He's highly interested in developer productivity (and tools like Maven and AOP/AspectJ), web frameworks, Java portals, testing and performance and works a lot with IBM technologies. A native to Czech Republic, he lives now in Oslo, Norway. Jakub is a DZone MVB and is not an employee of DZone and has posted 155 posts at DZone. You can read more from them at their website. View Full User Profile

What Is CDI, How Does It Relate to @EJB And Spring?

11.12.2011
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A brief overview of dependency injection in Java EE, the difference between @Resource/@EJB and @Inject, and how does that all relate to Spring – mostly in the form of links.

Context Dependency Injection (CDI, JSR 299) is a part of Java EE 6 Web Profile and itself builds on Dependency Injection for Java (JSR 330), which introduces @Inject, @Named etc. While JSR 330 is for DI only and is implemented e.g. by Guice and Spring, CDI adds various EE stuff such as @RequestScoped, interceptors/decorators, producers, eventing and a base for integration with JSF, EJBs etc. Java EE components such as EJBs have been redefined to build on top of CDI (=> @Stateless is now a CDI managed bean with additional services).

A key part of CDI aside of its DI capabilities is its awarness of bean contexts and the management of bean lifecycle and dependencies within those contexts (such as @RequestScoped or @ConversationScoped).

CDI is extensible – you can define new context scopes, drop-in interceptors and decorators, make other beans (e.g. from Spring) available for CDI,… .

Resources to check:

Note: CDI 1.1 (JSR 346, Java EE 7) should have a standard way of bootstrapping it in non-EE environment (i.e. SE)

 

From http://theholyjava.wordpress.com/2011/11/09/what-is-cdi-how-does-it-relate-to-ejb-and-spring/

Published at DZone with permission of Jakub Holý, author and DZone MVB.

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