Mastering Spring Security Fundamentals

Spring Security is a powerful, highly customizable authentication and access-control framework. It is the de-facto standard for securing Spring-based applications, providing comprehensive protection against common vulnerabilities.

Spring Security's core components include AuthenticationManager, AccessDecisionManager, and SecurityContextHolder. These facilitate principal authentication, authorization decision-making, and context awareness of authentication state, respectively.

A chain of filters manages security, including authentication and authorization. Each request goes through this chain, allowing granular control over security, such as session management and CSRF protection.

Beyond URL-based security, Spring Security also secures at the method level. Annotations like @PreAuthorize, @PostAuthorize, and @Secured let developers implement fine-grained control over application's methods.

Spring Security provides extensive support for modern authentication protocols, including OAuth 2.0 and OIDC. It allows seamless integration with external identity providers and SSO solutions.

With Spring Security, sessions can be managed in sophisticated ways. Features include concurrent session control, session fixation protection, and remember-me services for persistent authentication.

Spring Security is highly extensible. It not only allows custom user-detail services and password encoders but also supports custom filters and access decision voters for tailored security requirements.