[Springframework-developer] Creating Application Context getBean 'closures'

[Colin S. <col...@ex...>]

I think I may be missing something, but I think it's desireable to be 
able to create in an easy fashion, 'closures' which encapsulate getting 
a bean from a bean factory.

Say you have an interface
  interface MyInteface {   ... whatever }

and you have a factory Interface
  interface MyInterfaceFactory {
    MyInterface getInstance();
  }

And you have a user of the factory, who you'd rather have no knowledge 
of Spring, which is why he's using the factory instead of calling 
getBean himself:
class User {
  MyInterfaceFactory _myfac;
  public void setMyInterfaceFactory(MyInterfaceFactory myfac) { _myfac = 
myfac; }
  public void someMethod() {
    // need a new instance of MyInterface to work with
    MyInterface myint = _myfac.getInstance();
      ...
  }
}

Now I have a bean factory
<beans>
  <bean id="myinterface" singleton="false" 
class="com.whatever.MyInterfaceImpl">
  </bean>
  <bean id="user" class="com.whatever.User">
    <property name="myInterfaceFactory"><ref bean="xxxxxxxx"/></property>
  </bean>
</beans>

now, as per the above, context.getBean("myinterface") is already a 
factory for objects implementing MyInterface. But I don't want the User 
object to know anything about contexts. And I'd rather not create an 
actual object that implements MyInterfaceFactory. It seems like a waste, 
since all I am doing here is trying to create a level of indirection, 
and I already have a factory inside the context itself, and I may want 
to use this approach in 30 different places, just to add a level of 
indirection in creating new objects.

So what I think is needed is some variation of ProxyFactoryBean (but a 
separate class), which given a target bean (which is itself a factory), 
and a factory interface having a method with no args which returns a 
certain type, creates on the fly a new class implementing the factory 
interface, which will just use the target factory bean to actually 
supply the instance. So the bean def above would become:
<beans>
  <bean id="myinterface" singleton="false" 
class="com.whatever.MyInterfaceImpl">
  </bean>
  <bean id="myinterface-factory" class="org.springframework.whatever.XXXX">
    <property name="targetBean"><ref bean="xxxxxxxx"/></property>
    <property 
name="interface"><value>x.y.z.AFactoryInterface</value></property>
  </bean>
  <bean id="user" class="com.whatever.User">
    <property name="myInterfaceFactory"><ref 
bean="myinterface-factory"/></property>
  </bean>
</beans>

Am I missing an existing way to do this? Is this worth adding to spring 
as a convenience built-in, along the lines of TransactionProxyFactoryBean?