The Spring framework looks like a good deal. Has anyone used it on a large project? I'm wondering about two types of "large". Large being many classes, subsystems,..etc. Does the config become unweildy, not worth the effort? Large meaning scaling to many users in a web app. Who (large scalable site, or large scalable product) already uses Spring? I'm trying to justify training cost to my manager.
Where I work we use Spring as our service provider/manager. We have about a hundred DAOs and various other supporting beans. Spring allows you to have one context file import another without having to reconfigure your main loader. We use this to break down our context files into manageable chunks based on functionality groups. It works great and it is really great for doing unit/mock testing.
Our app spans three server layers (web, application & supporting services) and we use pretty much all of the J2EE API. Each layer also has a redundant failover box as well. It is a high traffic application that serves user applications and content.
Spring is also very easy to use and learn... the cost should be a book or two and a handful of hours on the Spring website (http://www.springframework.org).