How to create bean using @Bean in spring boot for abstract class

Question

I have requirement to migrate old style spring project to Spring boot. Assume below code snippet I have to migrate to Spring boot style.

Here my ask , how to conver

Answer 1

Write your abstract base class in plain Java (without any Spring coupling) :

public abstract class AbstractClass{   
    private Sample1 sample1;
    private Sample2 sample2;

    public AbstractClass(Sample1 sample1, Sample1 sample2){
       this.sample1 = sample1;
       this.sample2 = sample2;
   }
   ... 
}

Note that adding a constructor with parameters (both for the abstract class and the concrete class) makes injection easier and dependencies clearer.

Then you have two ways :

1) Annotate the concrete class(es) with @Component.
Such as :

@Component
public class MyClass extends AbstractClass{   
    public MyClass (Sample1 sample1, Sample1 sample2){
        super(sample1, sample2);
    }
}

This first way has the advantage to be short : just an annotation to add.
But it makes de facto the subclass as a bean that may potentially be loaded by the Spring context.

2) Alternatively, declare the bean in a Configuration class.
Such as :

@Configuration
public class MyConfig{
  @Bean
   public MyClass myClass(Sample1 sample1, Sample1 sample2){
      return new MyClass(sample1, sample1);
   }
}

This second way is more verbose but has the advantage to not modify the subclass code and also let clients of the class to decide whether the class should be a bean.

Each approach has its advantages and its drawbacks.
So to use according to the concrete requirement.