3

Is it possible to define a prototype bean, using XML config or annotation-based config such that I can get an instance of the bean with a custom parameter value? My use case is a message queue handler that makes API calls with different parameter values that are supplied in the inbound message.

In this case it seems I can do one of two things:

  • Get an instance of my prototype-scope bean and then call setters to customize it to be specific to the inbound message.
  • Construct a new instance of the bean class using a plain new MyPrototypeBean() and then call setters to customize the instance.

Perhaps a different way of wording my question is: What is the benefit of using a prototype-scope bean vs. using a simple Java constructor?

ben75
  • 29,217
  • 10
  • 88
  • 134
Marty Chang
  • 6,269
  • 5
  • 16
  • 25

1 Answers1

2

To get a prototype bean from another bean while passing arguments to constructor you can use <lookup-method> (XML Configuration) or @Lookup (annotation-based configuration).

If you want to get the prototype instance from "unmanaged" code (not from a bean) or you don't want to use the lookup methods, you can achieve the same using org.springframework.beans.factory.BeanFactory.getBean(String beanName, Object...).

Answering your second question, difference between a prototype-scope bean and using a simple Java constructor is that the prototype-scope bean still have access to Spring container's features. This includes, but it's not limited to the following: it can have collaborators provided in XML configuration (<property name="someCollaborator" ref="..."/>) or with annotations (@Resource, @Autowired, ...), t can implement Spring-aware interfaces (like ApplicationContextAware so that the prototype bean itself has access to the container).

Piotr Findeisen
  • 19,480
  • 2
  • 52
  • 82
  • Thanks, and can you edit your answer to put the `@Lookup` method paragraph first? Pivotal Support confirmed your answer and said that `@Lookup` is the better approach, presumably for the same reason you cited above. – Marty Chang May 06 '16 at 13:22
  • Thanks, i've rearranged the answer accordingly. – Piotr Findeisen May 06 '16 at 13:28
  • @PiotrFindeisen I have to implement something similar. How can i pass an oject at runtime to a prototype bean which I am getting from Spring Service Locator. The Service Locator method just takes a String argument which is basically a mapping to the spring bean id/name. – bluelurker Mar 24 '17 at 05:38
  • @bluelurker sorry, but i don't know what Spring Service Locator is. – Piotr Findeisen Mar 25 '17 at 20:25
  • @PiotrFindeisen this: http://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/beans/factory/config/ServiceLocatorFactoryBean.html – bluelurker Mar 26 '17 at 14:18