如何将 spring bean 自动连接到 EventListener

Question

i am searching for a way to create a listener that is also a spring component, however when i try to autowire the entity manager bean, it is always null, what am i doing wrong?

@Component
public class TestListener {

    @Autowired
    private TestRepository entityManager;

    @PrePersist
    @PreUpdate
    void beforeEntityUpdateOrSave(final Entity entity) {
        entityManager.someOperation() // -> NullPointerException, because the bean is "null"
    }
}

the Entity class has the listener in the @EntityListeners annotation.

@EntityListeners(TestListener.class)
public class Entity 

Answer 1

Is the class TestRepository annotated with @Repository?

You could try making the field entityManager final. I would also recomend using constructor injection instead. Field injection sometimes leads to strange behaviour.

@Component
public class TestListener {

    private final TestRepository entityManager;

    public TestListener(@Autowired TestRepository entityManager){
        this.entityManager = entityManager;
    }

    ...

    }
}