Custom Annotation Articles

How to Create Custom Validation Annotations in Spring Boot - @Constraint/ConstraintValidator Implementation Guide

A step-by-step guide to creating custom validations with @Constraint and ConstraintValidator, covering three patterns: phone number format, email duplication check (using DI), and password confirmation (cross-field). Encapsulate rules that @NotBlank / @Pattern cannot handle into reusable annotations and consolidate validation logic scattered across the Service layer.

2026-02-21