Question

I have a problem with Spring: I need to reuse the same instance of bean twice, but not making it singleton.

Here is a brief ApplicationContext:

<bean class="a.b.c.Provider" id="defaultProvider" scope="prototype">
    <constructor-arg ref="lifecycle" />
    <constructor-arg ref="propertySetter" />
</bean>

<bean name="lifecycle" class="a.b.c.Lifecycle" scope="prototype">
        <constructor-arg ref="someParam" />
        ... and more args
</bean>

<bean id="propertySetter" class="a.b.c.PropertySetter" scope="prototype">
    <constructor-arg ref="lifecycle" />
</bean>

So, I need to have fully initialized Provider with Lifecycle and PropertySetter inside,
and this PropertySetter must contain reference to same Lifecycle, as the Provider have.

When I define lifecycle and propertySetter as singletons, it causes big problems, because
if I create more than one Provider, all instances of Provider class shares same lifecycle
and property setter, and it’s breaking application logic.

When I try to define all beans as prototypes, Lifecycles in Provider and in PropertySetter are not the same => exceptions again.

I have one solution: to pass to Provider only Lifecycle and create PropertySetter inside Provider java constructor (by extending Provider).
It is working well, but only in my local environment. In production code I can’t extend 3pty Provider class, so I can’t use this solution.

Please advise me, what most appropriate to do in this situation?

Answer 1

You don’t need to extend Provider. Just create your own ProviderFactory that will take reference to lifecycle and will create PropertySetter and then Provider:

public class ProviderFactory {

  public static create(Lifecycle lc) {
    return new Provider(lc, new PropertySetter(lc));
  }
}

Here is Spring declaration:

<bean id="defaultProvider" scope="prototype" 
      class="a.b.c.ProviderFactory" factory-method="create">
    <constructor-arg ref="lifecycle" />
</bean>