Java web frameworks

Stripes seems to be quite lightweight and embraces Convention over Configuration.

Having used struts, wicket, rails & Tapestry, I recommend you look into Tapestry 5.

It supports

• in container class reloading (so you dont have to restart your webapp each time you make a change)
• fast development time & increased productivity - it uses a component based model, with declarative wiring
• minimal configuration, which is mostly in code anyway, convention over config - etc..
• No base classes to extend
• An expression language for use in template files
• good ajax support
• excellent debugging support, both client and server side
• good data access integration
• an active community
• written from the ground up with performance in mind. e.g. page pooling (to minimise resource usage), page compression, whitespace elimination, all dynamic code is compiled to native.
• good bean and form support - making common tasks simple. A sortable database backed drid can be coded with just one line of template code, and a minimal skeleton server backend.

the only downside is the documentation, which, is good, but a little terse, although the user groups/mailing lists are very active and most questions are answered well & eagerly.

(Also, be sure to only look at T5 - and not T4,3,2,1..... as these are very different to the current version)

More on why here.