Inject Bean into CDI Context programmatically?

问题

Is it possible to manually Inject a bean into a CDI context? With the JBoss Seam framework, I could always do something like Contexts.getConversationContext().set("foo", bar); and the Bean would become part of that context. Is it possible to do something like this in Java EE 6 CDI?

回答1:

There is no way to do this in an implementation agnostic way. You'd have to dig into the implementation, find the scope objects, pull them out via a BeanManager and figure out how to add them. Not all of them (quite possibly none of them) are as easy to set as maps.

回答2:

With CDI you have to slightly change the way you think about the scoped beans. In Seam2 the contexts are just maps that are held in a specific scope and you have access to these maps. In CDI the container gets the control over the contexts and allows you only to declare beans in a concrete scope and everything gets managed behind the scene without access to the scope maps. This is done because CDI philosophy is to keep the things type-safe and just setting things in a map with a string as a value and injecting them by their string key isn't type-safe at all.

To achieve the goal you want create a "holder" bean in the concrete scope and hold your values there.

@Named
@ConversationScoped
public class UserManager {

  private User currentUser;

  //getters and setters for currentUser

}

In this sample the a User instance is held in the conversation scope by setting it in the conversation-scoped bean. This is completely type-safe as you can inject the UserManager anywhere you want just by using @Inject (actually it's bean type gets used) avoiding string keys (as in Seam2) that are unsafe when doing refactoring.