RBAC Done Right: Spring Security, JWT, JSON Login, and BCrypt
Most Java enterprise backends still run Spring Security with JWT and BCrypt; this walkthrough shows the exact integration steps, which is what developers will encounter when maintaining real codebases.
This guide walks through the full permission system design using RBAC models, from the basic RBAC0 to the more constrained RBAC2 and RBAC3, then shows how to implement it in Spring Security. It covers the default Spring Security setup, in-memory users, HTTP request interception, and then integrates JWT for stateless authentication. The JWT section includes a custom filter, a token utility class, and a UserDetailsService implementation. Later, it explains how to enable JSON-based login by overriding the UsernamePasswordAuthenticationFilter, and how to use BCrypt for password hashing. Finally, it demonstrates database-backed authentication by wiring a custom UserDetailsService into the SecurityConfig.
The guide uses the deprecated WebSecurityConfigurerAdapter, which is no longer the recommended approach in Spring Security 5.7+; developers need to adapt these patterns to the new component-based configuration.
The tutorial correctly moves from an insecure NoOpPasswordEncoder to BCrypt, but the default Spring Security setup still accepts plain text in memory unless overridden, so it's easy to leave insecure config in place.
The JSON login override is a common need for SPAs, but the guide does not cover CSRF or CORS beyond a basic setup, which is a typical omission in tutorials.