Question

I need to create an Object which is in-complete without the constructor argument. Something like this

Class A  {
  private final int timeOut
  public A(int timeout)
  {
     this.timeOut = timeout;
   }
 //...
}

I would like this Bean to be spring managed, so that I can use Spring AOP later.

<bean id="myBean" class="A" singleton="false">
</bean>

However my bean needs timeout to be passed as a dynamic value – is there a way to create a spring managed bean with dynamic value being injedcted in the constructor?

Answer 1

BeanFactory has a getBean(String name, Object... args) method which, according to the javadoc, allows you to specify constructor arguments which are used to override the bean definition’s own arguments. So you could put a default value in the beans file, and then specify the “real” runtime values when required, e.g.

<bean id="myBean" class="A" scope="prototype">
   <constructor-arg value="0"/> <!-- dummy value -->
</bean>

and then:

getBean("myBean", myTimeoutValue);

I haven’t tried this myself, but it should work.

P.S. scope="prototype" is now preferable to singleton="false", which is deprecated syntax – it’s more explicit, but does the same thing.