Home How many instance(s) of @Autowired "prototype" bean is(are) created during the usage of a @Component

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How many instance(s) of @Autowired "prototype" bean is(are) created during the usage of a @Component

April 25, 2022

I have a Managerclass annotated with @Component  and @Scope

@Component     
@Scope(value = "prototype")     
public class Manager {
   ...
}

So I expect a new instance of the Manager bean will be created each time the bean is requested.

Then I have an Adapter class which uses this Manager bean. To use it, I have two ways of Autowire: 1. on the property or 2. on the constructor:

@Component     
public class Adapter {
    @Autowired     
    Manager m_Manager;

    ...
}

@Component     
public class Adapter {
    Manager m_manager;

    @Autowired     
    public Adapter(Manager manager) {
        m_manager = manager;
    }

    ...
}

Since the Adaptor class is a singleton bean, so both @Autowire the Manageron the property or on the constructor will only create one instance of the Manager? Meaning Managerbean is actually used as a singleton bean instead of prototype bean, right?

>Solution :

@Autowire behaves in the same way as ApplicationContext.getBean

It creates a prototype bean for each autowired instance. you can see that the prototype object in two singletons has a different identifier

So each singleton has its own prototype instance. It doesn’t have any difference if you do it with @Autowire in the constructor or field.
Do Autowire on constructor is just more convenient way to avoid annotation duplication.

P.S. To define scope is better to use