One of the aspects of Spring that makes it such a useful framework for real developers who are building real applications is its wealth of well-written, accurate documentation. One of the key goals for the 1.1 release was to ensure that all the documentation was finished off and polished by the development team. This means that every feature of Spring is not only fully documented in the JavaDoc, but is also covered in the Spring reference manual included in every distribution.
If you haven't yet familiarized yourself with the Spring JavaDoc and the reference manual, do so now. This book does not aim to be a replacement for either of these resources; rather, it aims to be a complementary reference, demonstrating how to build a Spring-based application from the ground up.