handling Multiple implementation of interface

Question

Say I need to rely on several implementations of a Spring bean. I have one AccountService interface and many implementations: DefaultAccountServiceImpl,SpecializedAccountServiceImpl and etc(actual count is 40).

How is this possible (injecting one or the other implementation) in Spring boot?

Which implementation will the following injection use?

Szellem · Accepted Answer · 2019-04-09 12:10:30Z

1

According to this article https://www.logicbig.com/tutorials/spring-framework/spring-core/inject-bean-by-name.html, if there are multiple implementations, a NoUniqueBeanDefinitionException will be thrown. This can be fixed with @Qualifier annotation, where the name of the desired bean should be given.

answered Apr 9, 2019 at 12:10

Szellem

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Houssam Badri · Accepted Answer · 2019-04-09 12:26:06Z

0

Use @Qualifier annotation of Spring boot, when autowiring it.

Example:

@Autowired
@Qualifier("defaultAccountServiceImpl")
AccountService defaultAccountServer;

@Autowired
@Qualifier("specializedAccountServiceImpl")
AccountService specializedAccountServiceImpl;

answered Apr 9, 2019 at 12:26

Houssam Badri

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5 Comments

Mithunkumar Over a year ago

if i add as you have mentioned, i need to autowire 40 qualifier beans?

Mithunkumar Over a year ago

Hi Husam, Thanks. i got a instance of a class from the below code. Class<? extends <Interface-name>> sanitizer = EntityServiceImplMap.getInstance().getSortSanitizer(entityId, subEntityId); Now i have userimpl.class value in sanitizer. but when i am accessing the userimpl class methods, i couldnot access it through my sanitizer obj. how can i achieve?

Houssam Badri Over a year ago

If you need each of your implementation so you have to implement all of them. But you may use Abstract class. I didn't get your above comment sorry.

Mithunkumar Over a year ago

Thanks, EntityServiceImplMap.getInstance().getSortSanitizer(entityId, subEntityId) is giving the return value as "RolesServiceImpl.class". After getting this value i cannot call the methods from my RolesServiceImpl class through the reference "sanitizer". when i am trying to call sanitizer.newInstance(), I am getting null error for other autowired properties

Houssam Badri Over a year ago

No problem, check if you may have missed annotating your classes with @Component so that they could be managed by Spring

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