spring - How to create a specific validator for a field's model -

i want use specific validation field in class. should assure username field follow specific rules.

can point me docs show me how create validator field in class?

i'm using spring framework.

whats wrong spring documentation.

the page http://docs.spring.io/spring/docs/current/spring-framework-reference/html/validation.html

there different ways that. prefer javax.validation spring integration instead of system spring directly. creation of custom validator object can seen in hibernate-validator (implementation of javax.validation) https://docs.jboss.org/hibernate/validator/4.0.1/reference/en/html/validator-customconstraints.html