在自己的Java框架中支持多个DI容器

Question

In my own multi-purpose Java framework, how to use dependency injection without depending on a concrete DI container? That is, any application should be able to use my framework, no matter whether it uses CDI, Spring or Guice itself.

All of the following should be possible:

• for my framework to inject dependencies into the application
• for the application to inject dependencies into my framework
• for a component of my framework to inject dependencies into another component

Answer 1

JSR 330: Dependency Injection for Java is the specification with the largest level of consensus within the dependency injection community and as a result is supported by:

• Spring since version 3.0: http://spring.io/blog/2009/09/29/spring-framework-3-0-rc1-released/ ,
• In Guice starting version 3.0: https://github.com/google/guice/wiki/JSR330 ,
• In CDI ( JSR 299 , JSR 346 ) specification which leverages JSR 330 thus supported by the Weld and OpenWebBeans implementations.

That makes JSR 330 the best common denominator to have portability accross the dependency injection frameworks. Which obviously comes at the cost of the range of functionalities.

Answer 2

You'll have to come up with a lowest common denominator interface for all DI operations you need and implementations for each concrete instance you may want to use.

You can't have any DI engine specific annotations in your objects, so you'll have to externalize all configuration and use setter or constructor injection for all objects.

Personally, I think this is a waste of time. DI ought to be a commodity. I'd see no good reason for switching DI engines. It's more likely that you'll choose one that meets your needs and stick with it.