I would use a factory to create the proxies. This would occur inside of the Struts action. Then, in the JSP, you could access the collections as you normally would.
--Kevin -----Original Message----- From: Kris Schneider [mailto:kris@;dotech.com] Sent: Wednesday, October 30, 2002 4:57 PM To: Struts Users Mailing List Subject: RE: [OT] Getting a Collection's size in JSTL But applying a proxy to this scenario seems like overkill. Wouldn't you have to do something like the following: public interface CollectionInfo { public int getSize(); } public class CollectionHandler implements InvocationHandler { private Collection c; public CollectionHandler(Collection c) { this.c = c; } public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { if ("getSize".equals(method.getName())) { return new Integer(this.c.size()); } else { return method.invoke(this.c, args); } } } InvocationHandler handler = new CollectionHandler(theCollection); Object proxy = Proxy.newProxyInstance(classLoader, new Class[] { Collection.class, CollectionInfo.class }, handler); request.setAttribute("collectionProxy", proxy); Which may not be horrible if you're using a servlet or Action, but how would you use it in a JSP-only situation? Quoting "Kevin A. Smith" <[EMAIL PROTECTED]>: > I'm referring to the java.lang.reflect.InvocationHandler. You can use it > create proxy objects for interfaces "on-the-fly". I've used it extensively as > a way of adapting mismatched interfaces between objects. > > --Kevin > > -----Original Message----- > From: David Graham [mailto:dgraham1980@;hotmail.com] > Sent: Wednesday, October 30, 2002 4:35 PM > To: [EMAIL PROTECTED] > Subject: RE: [OT] Getting a Collection's size in JSTL > > > What is a DynamicProxy? We may be talking about the same pattern with > different names. > > David > > > > > > > >From: "Kevin A. Smith" <[EMAIL PROTECTED]> > >Reply-To: "Struts Users Mailing List" <[EMAIL PROTECTED]> > >To: "Struts Users Mailing List" <[EMAIL PROTECTED]> > >Subject: RE: [OT] Getting a Collection's size in JSTL > >Date: Wed, 30 Oct 2002 16:31:03 -0500 > > > >This also seems like a good place to use a DynamicProxy. Since most all of > > >the Java Collections package is interfaced base, this seems like it might > >be an elegant solution. > > > >--Kevin > > > >-----Original Message----- > >From: David Graham [mailto:dgraham1980@;hotmail.com] > >Sent: Wednesday, October 30, 2002 3:44 PM > >To: [EMAIL PROTECTED] > >Subject: Re: [OT] Getting a Collection's size in JSTL > > > > > >That's pretty much what I did except you can only set the internal > >collection in the constructor. It's an elegant solution that should > >probably (in some form) be included in a larger library. > > > >David > > > > > > > > > > > > > > >From: Kris Schneider <[EMAIL PROTECTED]> > > >Reply-To: "Struts Users Mailing List" <[EMAIL PROTECTED]> > > >To: Struts Users Mailing List <[EMAIL PROTECTED]> > > >Subject: Re: [OT] Getting a Collection's size in JSTL > > >Date: Wed, 30 Oct 2002 15:30:13 -0500 > > > > > >It should also be relatively painless to use a composition/delegation > > >approach. > > > > > >public class CollectionBean { > > > > > > private Collection c; > > > > > > public int getSize() { > > > return this.c.size(); > > > } > > > > > > public void setCollection(Collection c) { > > > this.c = c; > > > } > > > > > > public Collection getCollection() { > > > return this.c; > > > } > > >} > > > > > ><jsp:useBean id="collBean" class="com.foo.CollectionBean"/> > > ><c:set target="${collBean}" > > > property="collection" > > > value="${requestScope.theCollection}"/> > > ><c:out value="${collBean.size}"/> > > > > > >Or something along those lines. Of course, you could completely set up > >the > > >collection bean prior to hitting the JSP as well. > > > > > >Quoting David Graham <[EMAIL PROTECTED]>: > > > > > > > I actually thought of a better idea which is getting into commons > > > > collections territory but I'll post a quick description here. I made > > >a > > > > JstlCollectionWrapper class that wraps any Collection object and > > >implements > > > > > > > > the Collection interface. I added a getSize() method to this class. > > >The > > > > business layer classes can return standard Java collections like > > >ArrayList > > > > and you can wrap them in this class when using them in JSTL. > > > > > > > > A similar approach could be taken with the Map interface. I wish > they > > >would > > > > > > > > just add getSize to the standard classes :-(. > > > > > > > > David > > > > > >-- > > >Kris Schneider <mailto:kris@;dotech.com> > > >D.O.Tech <http://www.dotech.com/> > > > > > >-- > > >To unsubscribe, e-mail: > > ><mailto:struts-user-unsubscribe@;jakarta.apache.org> > > >For additional commands, e-mail: > > ><mailto:struts-user-help@;jakarta.apache.org> > > > > > >_________________________________________________________________ > >Protect your PC - get McAfee.com VirusScan Online > >http://clinic.mcafee.com/clinic/ibuy/campaign.asp?cid=3963 > > > > > >-- > >To unsubscribe, e-mail: > ><mailto:struts-user-unsubscribe@;jakarta.apache.org> > >For additional commands, e-mail: > ><mailto:struts-user-help@;jakarta.apache.org> > > > > > >-- > >To unsubscribe, e-mail: > ><mailto:struts-user-unsubscribe@;jakarta.apache.org> > >For additional commands, e-mail: > ><mailto:struts-user-help@;jakarta.apache.org> > > > _________________________________________________________________ > Unlimited Internet access for only $21.95/month. Try MSN! > http://resourcecenter.msn.com/access/plans/2monthsfree.asp > > > -- > To unsubscribe, e-mail: > <mailto:struts-user-unsubscribe@;jakarta.apache.org> > For additional commands, e-mail: > <mailto:struts-user-help@;jakarta.apache.org> > > > -- > To unsubscribe, e-mail: > <mailto:struts-user-unsubscribe@;jakarta.apache.org> > For additional commands, e-mail: > <mailto:struts-user-help@;jakarta.apache.org> > > -- Kris Schneider <mailto:kris@;dotech.com> D.O.Tech <http://www.dotech.com/> -- To unsubscribe, e-mail: <mailto:struts-user-unsubscribe@;jakarta.apache.org> For additional commands, e-mail: <mailto:struts-user-help@;jakarta.apache.org> -- To unsubscribe, e-mail: <mailto:struts-user-unsubscribe@;jakarta.apache.org> For additional commands, e-mail: <mailto:struts-user-help@;jakarta.apache.org>
