Question

We have a framework built on top of spring and we would like to give devs the ability to override our default beans. So in a case of our “custom themer”, (I wish we didn’t have a custom themer) we have an interface that we autowire into the theme bean.

How can we give the user the ability to implement the same interface and we have that bean autowired into our themer class instead of our default on. Lets say the interface was call NLSER and our default implementation was NLSERConcrete, how can the end user/developer inject CustomerNLSER instead?

Answer 1

Use the @Primary annotation or primary="true" bean attribute in XML. This is your default bean:

@Service
public class NLSERConcrete implements NLSER {//...

//...in different class
@Autowired
private NLSER nlser;

Now if the developer adds:

@Service
@Primary
public class CustomerNLSER implements NLSER {//...

to the CLASSPATH and Spring picks it up, it will be preferred in the process of autowiring.