Spring: get all Beans of certain interface AND type

In my Spring Boot application, suppose I have interface in Java:

public interface MyFilter<E extends SomeDataInterface>

(a good example is Spring's public interface ApplicationListener< E extends ApplicationEvent > )

and I have couple of implementations like:

@Component
public class DesignatedFilter1 implements MyFilter<SpecificDataInterface>{...}


@Component
public class DesignatedFilter2 implements MyFilter<SpecificDataInterface>{...}


@Component
public class DesignatedFilter3 implements MyFilter<AnotherSpecificDataInterface>{...}

Then, in some object I am interested to utilize all filters that implement MyFilter< SpecificDataInterface > but NOT MyFilter< AnotherSpecificDataInterface >

What would be the syntax for this?

67344 次浏览

小开

最佳答案

The following will inject every MyFilter instance that has a type that extends SpecificDataInterface as generic argument into the List.

@Autowired
private List<MyFilter<? extends SpecificDataInterface>> list;

小开

You can simply use

@Autowired
private List<MyFilter<SpecificDataInterface>> filters;

Edit 7/28/2020:

As Field injection is not recommended anymore Constructor injection should be used instead of field injection

With constructor injection:

class MyComponent {


private final List<MyFilter<SpecificDataInterface>> filters;


public MyComponent(List<MyFilter<SpecificDataInterface>> filters) {
this.filters = filters;
}
...
}

小开

In case you want a map, below code will work. The key is your defined method

private Map<String, MyFilter> factory = new HashMap<>();


@Autowired
public ReportFactory(ListableBeanFactory beanFactory) {
Collection<MyFilter> interfaces = beanFactory.getBeansOfType(MyFilter.class).values();
interfaces.forEach(filter -> factory.put(filter.getId(), filter));
}

小开

In case you want a Map<String, MyFilter>, where the key (String) represents the bean name:

private final Map<String, MyFilter> services;


public Foo(Map<String, MyFilter> services) {
this.services = services;
}

which is the recommended alternative to:

@Autowired
private Map<String, MyFilter> services;