Re: [Springframework-developer] Re: feature request

[Juergen H. <ju...@in...>]

Well, note the kind of default collection implementations that Spring uses:
It prefers ordered Maps and Sets if available, which also means that source
Maps specified on the FactoryBeans will preserve their order. You don't need
to do anything other than run on JDK 1.4+ (or with Commons Collections on
the classpath) to get this behavior for standard <map> / <set> / <list>
tags. No need to specify any special collection implementations for that.
 
For the LinkedList case (which I suppose is rather rare), why not simply use
ListFactoryBean with targetListClass=java.util.LinkedList?
 
Juergen
 


  _____  

From: spr...@li...
[mailto:spr...@li...] On Behalf Of
Crater, Jon (EDS)
Sent: Tuesday, July 19, 2005 8:26 PM
To: spr...@li...
Subject: [Springframework-developer] Re: feature request


Thanks for your reply.  I wasn't aware of the various factory bean classes
you mentioned, so this thread has already been useful.  What I really need,
though, is the ability to override the default Map/List/Set implementation
class on an as-needed basis.  So, for example, one of the properties of one
of my Spring-managed beans is a Map that needs to retain the order in which
it's configured, so I'd like to inject an instance of SequencedHashMap, but
I don't have a way to do that without extensions.  Using a MapFactoryBean
won't help me in this case because the order will not be preserved, as the
source map is required to have been created.
 
In another case, I may need to inject an instance of LinkedList, etc.  So, I
don't want to override every single one, just the ones where my needs
diverge from what is built-in.  If a "type" attribute isn't justified, is
there another way?
 ________________________________ 
 Actually, this can already be achieved through using MapFactoryBean,

 ListFactoryBean and SetFactoryBean, respectively - passing a source <map> /

 <list> / <set> in and specifying the desired "targetMapClass" /

 "targetListClass" / "targetSetClass".

 

 I don"t see much advantage in a "type" attribute on the corresponding tags

 directly, actually. It"s not that common to override the collection

 implementations on a per-collection basis to justify a special shortcut for

 this, IMO.

 

 Or are you trying to centrally override the default Map / List / Set

 implementations that Spring uses for <map> / <list> / <set>? Specifying

 those implementation classes _once_ rather than repeating them for every

 single collection definition?

 

 Juergen

  

 

 ________________________________

 

 From: springframework-developer-admin@li...

 [mailto:springframework-developer-admin@li...] On Behalf Of

 Crater, Jon (EDS)

 Sent: Tuesday, July 19, 2005 5:34 PM

 To: springframework-developer@li...

 Subject: [Springframework-developer] feature request

 

 

 i currently have a need to customize the implementation classes created
when

 spring parses the definitions for properties containing <map>, <list>, etc.

 elements.  currently i have to subclass AbstractXmlApplicationContext and

 override initBeanDefinitionReader(XmlBeanDefinitionReader r) to call

 setParserClass(Class c) with my own subclass of BeanDefinitionParser, which

 in turn overrides parseMapElement, etc.  i was hoping that future releases

 of spring could support this situation via out of the box configuration.
it

 seems like it would be fairly straightforward to respect a "type" attribute

 of the <map> and <list> (and any other) elements to support customization
of

 the Map/Collection implementation without requiring custom extensions.

  

 if there"s sufficient interest, i"d be happy to contribute.

  

 jon