Spring：获取特定接口和类型的所有 Bean

Question

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?

Answer 1

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;

Answer 2

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;
  }
  ...
}

Answer 3

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));
}

Answer 4

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;