Yes very clear thank you so the default assignment of scope=singleton happens under these scenarios: 1)bean creation defaulting to singleton as in ApplicationContext 2)beanFactory supports registerSingleton then a singleton bean can be set to lazy-initialize (that is not be pre-instantiated).
For all other situations the default of prototype is implied This statement about Method Injection is extremely problematic woth regards to singletons For most application scenarios, the majority of the beans in the container will be singletons. When a singleton bean needs to collaborate with another singleton bean, or a non-singleton bean needs to collaborate with another non-singleton bean, the typical and common approach of handling this dependency by defining one bean to be a property of the other is quite adequate. There is a problem when the bean lifecycles are different. Consider a singleton bean A which needs to use a non-singleton (prototype) bean B, perhaps on each method invocation on A. The container will only create the singleton bean A once, and thus only get the opportunity to set the properties once. There is no opportunity for the container to provide bean A with a new instance of bean B every time one is needed. So if prototype bean B changes A has no clue.. I think I'll stay with the scope="prototype/singleton" in the declarator.. Thanks, Martin ----- Original Message ----- From: "Randy Burgess" <[EMAIL PROTECTED]> To: "Struts Users Mailing List" <user@struts.apache.org> Sent: Tuesday, April 15, 2008 9:51 AM Subject: Re: [S2] Spring: Interceptors, prototype or singleton? > Just about every single S2 action I have ever created uses Spring to inject > a service object of some sort into the action. I use Spring for > transactions, SLSB's, MDB's, JDBC, Hibernate, you name it. > > Ganfab asked about injecting a new instance of an object into a custom > interceptor on every action call and my thinking was that Spring had only > constructor or setter injection and that interceptors were always > singletons, so the injected bean would always be a singleton. Well I just > found in Spring 2.5 they have lookup method injection which can be used to > create a new instance of an object from the Spring bean factory and inject > them into a Singleton. Using this you could inject new instances and declare > your interceptor in a package and not have to declare it for every action > needing this type of interceptor. See 3.3.7.1. > > http://static.springframework.org/spring/docs/2.5.x/reference/beans.html#bea > ns-factory-method-injection > > I hope I'm being clear about what I mean. :) > > Regards, > Randy Burgess > Sr. Web Applications Developer > Nuvox Communications > > > > > From: Martin Gainty <[EMAIL PROTECTED]> > > Reply-To: Struts Users Mailing List <user@struts.apache.org> > > Date: Mon, 14 Apr 2008 21:50:15 -0400 > > To: Struts Users Mailing List <user@struts.apache.org> > > Subject: Re: [S2] Spring: Interceptors, prototype or singleton? > > > > Could you provide a scenario where one bean is injected into another? > > > > Thanks > > M- > > ----- Original Message ----- > > From: "Randy Burgess" <[EMAIL PROTECTED]> > > To: "Struts Users Mailing List" <user@struts.apache.org> > > Sent: Monday, April 14, 2008 3:55 PM > > Subject: Re: [S2] Spring: Interceptors, prototype or singleton? > > > > > >> So the interceptor would have to be declared at the action level in this > >> case then? If I have a spring bean named myBean that is default scope and > > I > >> inject another bean declared as a prototype into it, the injected bean > > will > >> still be a singleton since there will be only one instance of myBean. > >> > >> Regards, > >> Randy Burgess > >> Sr. Web Applications Developer > >> Nuvox Communications > >> > >> > >> > >>> From: Don Brown <[EMAIL PROTECTED]> > >>> Reply-To: Struts Users Mailing List <user@struts.apache.org> > >>> Date: Tue, 15 Apr 2008 01:12:49 +1000 > >>> To: Struts Users Mailing List <user@struts.apache.org> > >>> Subject: Re: [S2] Spring: Interceptors, prototype or singleton? > >>> > >>> To clarify, interceptors aren't technically singletons as each > >>> instance in an interceptor stack gets its own interceptor instance. > >>> However, for all requests using that stack, the same interceptor will > >>> be used. Therefore, you do need to be careful. For example, most > >>> interceptors take parameters that configure their use within the > >>> stack, like the "validation" interceptor that takes a list of excluded > >>> methods from validation. Interceptors can be configured at the stack > >>> level or at the action level. If at the action level, you will get a > >>> unique interceptor instance for that action. > >>> > >>> If you want Spring to construct your interceptor, I recommend the > >>> prototype scope, so that Struts gets a new instance of the interceptor > >>> as expected. > >>> > >>> Don > >>> > >>> On Tue, Apr 15, 2008 at 12:48 AM, Randy Burgess <[EMAIL PROTECTED]> > > wrote: > >>>> Interceptors are Singletons according to the documentation. If it were > > me I > >>>> would come up with another method besides Spring for changing object > >>>> properties. > >>>> > >>>> Regards, > >>>> Randy Burgess > >>>> Sr. Web Applications Developer > >>>> Nuvox Communications > >>>> > >>>> > >>>> > >>>>> From: GF <[EMAIL PROTECTED]> > >>>>> Reply-To: Struts Users Mailing List <user@struts.apache.org> > >>>>> Date: Mon, 14 Apr 2008 14:51:25 +0200 > >>>>> To: Struts Users ML <user@struts.apache.org> > >>>>> Subject: [S2] Spring: Interceptors, prototype or singleton? > >>>> > >>>> > >>>>> > >>>>> In a guide I found on the web, the interceptor was defined as > > singleton in > >>>>> the Spring's ApplicationContext. > >>>>> > >>>>> If I need to use "changeable" object properties, I need to have it as > >>>>> Prototype, otherwise different requests will result in a object > > property > >>>>> overwriting. > >>>>> Is there any issues about defining an interceptor as Prototype, or is > > it ok? > >>>>> > >>>>> Thanks > >>>>> > >>>>> GF > >>>> > >>>> > >>>> > >>>> This email and any attachments ("Message") may contain legally > > privileged > >>>> and/or confidential information. 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