Spring is a lightweight container, with wrappers that make it easy to use many different services and frameworks. Lightweight containers accept any JavaBean, instead of specific types of components.
"Spring is more than just a 'lightweight container,'" says Justin Gehtland. "It allows Java developers who are building J2EE apps to get to the heart of their real domain problems and stop spending so much time on the minutiae of providing services to their domain." Gehtland and Bruce Tate are coauthors of Spring: A Developer's Notebook, a no-nonsense book that will get you up to speed quickly on the new Spring open source framework. Spring: A Developer's Notebook includes examples and practical applications that demonstrate exactly how to use Spring, in ten chapters of code-intensive labs.