I know I can not use @Autowired annotation in a non managed spring class. But I notice I do able to get a bean instance inside a non managed spring class if I am retrieving it through ApplicationContext getBean method. can someone explain me why is that ? what is the different between the options ? in both spring doesn't know the non managed class
2 Answers
3
votes
1) You can use @Autowired in a non-managed spring class if you use @Configurable -with the usage of internal aspect weaving spring will manage to autowired the referenced beans into your "Configurable" class when it is constructed with the "new" operator. Here is an article how this works: http://www.javacodegeeks.com/2013/09/spring-configurable-magic.html
If a class is not configurable spring cannot notice when a new instance is created to autowire its references.
2) The ApplicationContext is "Central interface to provide configuration for an application." Here you have access to the whole spring managed beans etc. That's why you can get everything due to accessing it via ApplicationContext. http://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/context/ApplicationContext.html
0
votes
ok, so here's the major points:
- the "bean declaration" (either in xml or java) is just a recipe of how to instantiate the object (not a object itself).
- when spring application boots, the beanFactory receives this recipes from beanDefinitionReader, instantiates objects according to them (recipes) and then pass them (objects) to a list of beanPostProcessors (several times) that are "injecting" dependences to the instantiated objects and then puts the objects into hashMap.
- roughly saying applicationContext is a class exposing access to this beans;
and that's how you can access this beans out of spring application using applicationContext.
another thing is that, actually you can inject beans into non managed beans through @Configurable. in this case the AspectJ would be used for making this work
