Hibernate Validator

This is an alternative to the spring validation framework. The difference is , spring validation framework is mainly for validating the forms at the web layer. Hibernate validator can be used to validate the bean at any of the layers e.g. web, business, data etc. Here is the tutorial on how to use it. Hibernate valuators are annotation based so only java 5 onwards its supported.
http://wheelersoftware.com/articles/hibernate-validator.html