Inject Service dynamically from Database parameter CDI

Question

I have some services implementing same Interface. I want to use service dynamically according to a paramater from database.

I would like use CDI annotation but if not possible please tell me how i can achieve it ? a factory ?

We have several providers with service associated and following the rule in DB we will use service or other

Service1 implements IService1, IGeneralService{

public void run(){...};}

Service2 implements IService2, IGeneralService{

public void run(){...};}

then i will use it according to DB parameter like a country or other.

public class Test{
    @IGeneralService service;

public void getRunMethod(String numberService){
      service.run() (here it run the right service)
}
}

something like that. Any idea ?

I think the best approach is the factory. You will call a createInstance, and the factory decides (including the DB data) what implementation returns — David SK, Sep 12 '19 at 15:11
it was a pseudo exemple but yes i know only with factory but witth producer or annotation CDI it is more sexy ^^ — cyril, Sep 12 '19 at 17:39
Possible duplicate of [How to programmatically inject a Java CDI managed bean into a local variable in a (static) method](https://stackoverflow.com/questions/24798529/how-to-programmatically-inject-a-java-cdi-managed-bean-into-a-local-variable-in) — Kukeltje, Sep 13 '19 at 18:56

score 1 · Answer 1 · answered Sep 12 '19 at 15:48

Yes, your test class looks a lot like a factory. Keeping on with what you have, it might look like this:

public class Test{
    @IGeneralService service0;
    @IGeneralService service1;

    public void getRunMethod(String numberService){
      if(numberService == '0')
          service0.run() 
      if(numberService == '1')
          service1.run() 
    }
}

You can get fancier in terms of how you manage that list of services (a map, a list). But the drawback here might be that you have to inject each of your services explicitly.

You could also go another route and inject the BeanManager into your factory:

public class Test{
    @Inject
    BeanManager bm;

    public void getRunMethod(String numberService){
        IGeneralService svc = (IGeneralService) bm.getBeans(numberService).iterator().next();
        svc.run();
    }
}

And now you don't need to explicitly inject each service.

Those are the two basic approached you can use here. Which is better depends on your use cases.

2nd method look like great, i wanted to link database value ENUM to BEAN name automatic ^^ thanks — cyril, Sep 12 '19 at 17:43
with this method i have a exception : org.jboss.weld.bean.ManagedBean cannot be cast to IGeneralService — cyril, Sep 13 '19 at 15:04
My answer was in general and in broad strokes. You'll have to find out why your service is wrapped in that. — Robert Moskal, Sep 13 '19 at 16:13

score 1 · Answer 2 · answered Sep 26 '19 at 15:26

There is a far cleaner way to do it.

@interface Provider {
    String value(); // provider id retrieved from the db
}

class ProviderImpl extends AnnotationLiteral<Provider> implements Provider {
    String providerId;
    ProviderImpl(String providerId) { this.providerId = providerId;}
}

Then for each of your service provider, annotate them appropriately:

@Provider("provider-1")
class ProviderOneImpl implements ServiceProvider {}

Then the usage looks like this:

class ServiceProcessor {
   @Any
   @Inject
   Instance<ServiceProvider> serviceProviders;

   void doSomethingAwesome() {
      String enabledProvider = getCurrentProviderId();
      Provider provider = new ProviderImp(enabledProvider);
      ServiceProvider serviceProvider = serviceProviders.select(provider).get();
      serviceProvider.run();
   }
}

score 0 · Answer 3 · answered Sep 13 '19 at 17:20

0

thanks to all guys i finally implement this way :

How to programmatically inject a Java CDI managed bean into a local variable in a (static) method

it works

answered Sep 13 '19 at 17:20

cyril

872
6
29

like suggested as a duplicate? Then there is no need to create this as an answer but vote for it to be a duplicate too and post this as a comment ;-) – Kukeltje Nov 11 '19 at 11:40

score 0 · Answer 4 · answered Nov 11 '19 at 11:34

0

You can inject de interface :

@Inject
@Any
private Instance <Payment> paymentsLazy;

after in your method you can choose the implementation

Payment object = paymentsLazy.select(Cash.class).get ();

answered Nov 11 '19 at 11:34

Mattheus Cassundé

1
1

Inject Service dynamically from Database parameter CDI

4 Answers4