myfaces-users mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Beelen, Marco" <marco_bee...@merck.com>
Subject RE: Initializing Beans - Two problems
Date Tue, 08 May 2007 08:13:49 GMT
Hello Francisco,
 
There are some possible alternatives:
 
1) A JSF implementation should call the setters for the
managed-properties of your bean in the order in which they are specified
in the jsf-config.xml.
Your could add an addional property 'startInitialization' as the last
managed-property and perform the initialization in the setter for that
property.
 
2) Make your classes implement the interface InitializingBean and use
JSF-Spring (  http://jsf-spring.sourceforge.net/
<http://jsf-spring.sourceforge.net/>  ) to make sure that the
initializing method will be called.. ( There have been reports about
classloader issues with JSF-spring, but I didn't ran into them yet and
am using this to my satisfaction. )
 
3) When you are using Spring 2.0.x, you can move the definition of your
managed-bean entirely to a spring applicationContext.xml and use
org.springframework.beans.factory.InitializingBean without JSF-spring,
although I don't fancy this approach I heard of some whom favour this.
 
4) Start using a JSF1.2 implementation and using the @PostConstruct
annotation to mark the method to be called after the bean has been
created and it's managed-properties are set.
 
 
 
With kind regards,
  Marco Beelen
 
 
 
 
 

________________________________

From: Simon Lessard [mailto:simon.lessard.3@gmail.com] 
Sent: maandag 7 mei 2007 20:07
To: MyFaces Discussion
Subject: Re: Initializing Beans - Two problems


Hello Francisco,

You could implement your own VariableResolver using decorator pattern
delegating to the original resolver then initializing the bean if your
condition is true. The code would look as follow:

public Object resolveVariable(FacesContext context, String name) {
  Object o = delegate.resolveVariable(context, name);
  if (o != null && (o instanceof GenericBean)) {
    GenericBean bean = (GenericBean)o; 
    if (!bean.isPostback()) {
      logger.info("Initializing bean: " + bean);
      bean.initialize();
    }
  }
}

Regards,

~ Simon


On 5/7/07, Francisco Passos <francisco.passos@gmail.com> wrote: 

	Hello there.
	
	Please bear with me in this description.
	
	I'm trying to get my request-scoped beans to be initialized
(fetch stuff from database, etc.) whenever they do not originate from a
postback (and keeping the state during postbacks using t:saveState).
I've implemented a PhaseListener which checks for the proper conditions
I want to initialize my beans in and invokes a method from the bean
interface my beans implement. 
	
	This is my implementation of said PhaseListener:
	
	public void beforePhase(PhaseEvent event) {
	
	    if (event.getPhaseId().equals(PhaseId.APPLY_REQUEST_VALUES)
|| event.getPhaseId().equals(PhaseId.RENDER_RESPONSE )) {
	    
	        GenericBean bean = (GenericBean)
FacesContext.getCurrentInstance().getApplication().getVariableResolver()
.resolveVariable(FacesContext.getCurrentInstance(),
"pesquisaFichaBean");
	        if (bean != null && !bean.isPostback()) { 
	            logger.info("Initializing bean: " + bean);
	            bean.initialize();
	        }
	    }
	}
	
	
	However I have two problems with this approach.
	
	The first problem has to do with having to use the bean names
explicitly ("pesquisaFichaBean" in this example). Is there any way I can
know the names of the registered beans? Or is there another alternative
I'm not seeing? 
	
	
	The second problem is as follows. By now I have a couple of
beans that I use in my application. So, for this to work, I have to
repeat what I've shown above for the various beans. The problem is that
the resolveVariable method never returns null - even if I have not yet
instantiated any bean with that particular name. It seems to me that,
since no bean yet exists, it is instantiated (as it would be if it were
referenced in a xhtml page). 
	
	Which means that everytime I enter a new page (no postback), all
my instantiated beans are initialized and the remaining are instantiated
on the spot and initialized as well!!! This obviously brings me back to
the problem of accessing the database for nothing. 
	
	I hope I explained the situation well, here's an example:
suppose some pages require "beanA", others "beanB". When I enter a page
which references "beanA" but does not reference "beanB", both will be
initialized! The difference is beanA will be used and beanB will. 
	
	What solutions are there for this? Is there any way I can look
into the variables without triggering their instantiation?
	



------------------------------------------------------------------------------
Notice:  This e-mail message, together with any attachments, contains
information of Merck & Co., Inc. (One Merck Drive, Whitehouse Station,
New Jersey, USA 08889), and/or its affiliates (which may be known
outside the United States as Merck Frosst, Merck Sharp & Dohme or MSD
and in Japan, as Banyu - direct contact information for affiliates is 
available at http://www.merck.com/contact/contacts.html) that may be 
confidential, proprietary copyrighted and/or legally privileged. It is 
intended solely for the use of the individual or entity named on this 
message. If you are not the intended recipient, and have received this 
message in error, please notify us immediately by reply e-mail and then 
delete it from your system.

------------------------------------------------------------------------------
Mime
View raw message