Re: [Springframework-developer] BeanFactory partial pre-population with applicat

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

Venkat,

If you are willing to rely on the new GenericApplicationContext class 
which was introduced for Spring 1.1.2 (which is planned for release this 
weekend, but the code is in CVS already), there is an even easier mechanism.

Make a simple PassthroughFactoryBean, which always returns an object 
that it was fed as a constructor:
    static class PassthroughFactoryBean implements FactoryBean {
        private Object object;

        public PassthroughFactoryBean(Object object) {
            this.object = object;
        }
        public Object getObject() throws Exception {
            return object;
        }
        public Class getObjectType() {
            return object.getClass();
        }
        public boolean isSingleton() {
            return true;
        }
    }

now, just use GenericApplicationContext:

        GenericApplicationContext ctx = new GenericApplicationContext();
        ConfigurableListableBeanFactory factory = ctx.getBeanFactory();

        PassthroughFactoryBean communicatorFactory = new 
PassthroughFactoryBean(communicator);
        factory.registerSingleton("communicator", communicator);
       
        XmlBeanDefinitionReader xmlReader = new 
XmlBeanDefinitionReader(ctx);
        xmlReader.loadBeanDefinitions(new 
ClassPathResource(contextFileLocation));
       
        ctx.refresh();   

And after writing this, I just realized that even with a normal 
ClasspathXmlApplicationContext, what you should be able to do is just 
use the constructor with refresh=false to create the context but not 
initialize it yet, then just add the singleton factory bean exactly as 
above, then call refresh on it. Just be careful, as a subsequent refresh 
will not have the manually added singleton bean! That's why 
GenericApplicationContext doesn't even allow more than one refresh.

Colin


Venkat Sonnathi wrote:

> Hi Colin,
>
> Thanks for the solution, that was quite descriptive. As you said it 
> took me 10 min to implement.
>
> It would be nice to have a generic mechanism that is part of the 
> framework that will do the same, probably the requrement is not too 
> common to warrant that.
>
> Thanks again,
> --Venkat.
>
>
>
> From: Colin Sampaleanu <col...@ex...>
> Reply-To: spr...@li...
> To: spr...@li...
> Subject: Re: [Springframework-developer] BeanFactory partial 
> pre-population with application objects.
> Date: Tue, 02 Nov 2004 16:56:10 -0500
>
> There's probably some cleaner ways to handle this, but off the top of 
> my head I can think of one fairly easy mechanism that should take 10 
> minutes or less to implement.
>
> Sucblass ClasspathXmlApplicationContext to have a Communicator field, 
> and getCommunicator() method to get the value of this. When your 
> variant of ClasspathXmlApplicationContext is created, the Communicator 
> instance could be passed in as a constructor arg (make a new 
> constructor), or as a setter property (you would need to make sure to 
> use the existing constructor with refresh=false, for that approach). 
> To actually get at the Communicator instance inside the context def, 
> the user would just use a custom FactoryBean you define. This factory 
> bean would be ApplicationContextAware, so would have the context given 
> to it. All it would do on the getObject() method, is cast the context 
> to your subclass type, and return the value of the getCommunicator() 
> method.  All the user has to do when setting up their context.xml file 
> is remember to add in a one line bean definition for your factory:
>
> <bean id="communicator" class="x.y.z.CommunicatorFactoryBean"/>
>
>
> Regards,
> Colin
>
> Venkat Sonnathi wrote:
>
>> Hi,
>>
>> The subject may sound strange but please bear with me. I am trying to 
>> use Spring to isolate ICE (http://www.zeroc.com) specific 
>> depedencies. I could prototype the client side interaction (Thanks to 
>> Jurgen for pointing me in the right direction), but have come to a 
>> block when trying Server side.
>>
>> ICE has a kind of app server called IceBox, it loads different 
>> services from a Config file, it has a feature called 
>> UseSharedCommunicator, which means all the loaded services share the 
>> same ICE runtime instance and calls to other services located in the 
>> same instance are treated as local calls.
>>
>> Basically you wrap a ServiceImpl class in ServiceAdapter so that 
>> IceBox can load it, here is an example of the ServiceAdapter for a 
>> ServiceImpl class PrinterI
>>
>> public class IceBoxService  extends Ice.LocalObjectImpl implements 
>> IceBox.Service {
>>
>>        private Ice.ObjectAdapter adapter;
>>
>>        public void start(String s, Communicator communicator, 
>> String[] strings) {
>>
>>            this.adapter = communicator.createObjectAdapter(s);
>>            Ice.Object object = new PrinterI(communicator);
>>            adapter.add(object, 
>> Ice.Util.stringToIdentity("SimpleFCASearch"));
>>            adapter.activate();
>>        }
>>
>>        public void stop() {
>>            adapter.deactivate();
>>        }
>>    }
>>
>> }
>>
>> I was planning on writing a generic IceBoxService which takes a 
>> parameter to context.xml file and instantiate a BeanFactory which 
>> loads the ServiceImpls and resolve the services they depend upon.  
>> But, if you observe how the PrinterI is instantiated, the 
>> communicator instance passed to it should be one that is supplied by 
>> the IceBox server (passed in as a parameter to start method). How to 
>> make a bean factory aware of this communicator?
>>
>> The following code explains the behaviour I am looking for:
>> BeanFactory bf = new ClassPathXmlApplicationContext();
>> bf.setBean("communicator", communicator); // Setting/passing the 
>> application communicator instance to the Bean
>> bf.load("context.xml"); // refers to the communicator bean passed in 
>> above statement.
>>
>> Thanks for your time and patience.
>>
>> --Venkat.
>>
>>
>>
>>
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>
>
>
>
>
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