Dependency Injection Annotations To Come To A JVM Near You.

(Via Twitter, where else?)

Remember this (my blog reaction to Google Guice 1.0)? At the time I wondered:

Me:

Guice, Or Something Like It, Should Be In The JDK

About the only thing that makes feel a little bit uncomfortable is the use of Guice specific imports in my application code.

Wouldn't it be nice if I don't have to do a

import com.google.inject.*;

but do a

import java.lang.inject.*;

instead?

It's been 779 days since then, but Bob Lee and Rod Johnson have just made public a (work-in-progress) JSR JSR ?: Annotations for Dependency Injection "to standardize a proven, non-controversial set of annotations that make injectable classes portable across frameworks."

Bob Lee: Five years ago, Spring 1.0 brought Java dependency injection into the mainstream. Three years later, Google Guice 1.0 introduced annotation-based dependency injection and made Java programming a little easier. Since then, developers have had to choose between a) writing external configuration or b) importing vendor-specific annotations.

Today, we hope to give developers the best of both worlds. Google Guice and SpringSource have partnered to standardize a proven, non-controversial set of annotations that make injectable classes portable across frameworks. At the moment, the set of specified annotations consists of:

• @Inject - Identifies injectable constructors, methods, and fields
• @Qualifier - Identifies qualifier annotations
• @Scope - Identifies scope annotations
• @Named - String-based qualifier
• @Singleton - Identifies a type that the injector only instantiates once

One additional interface is specified for use in conjunction with these annotations:

• Provider<T> - Provides instances of a type T. For any type T that can be injected, you can also inject Provider<T>.

Responses[1]

Posted by Weiqi Gao on May 5, 2009 1:23:22 PM CDT #