🐉 AuthenticationFilter vs. Old Spring Security Logic (Dragon Ball Z Style Battle!)

🔥 Round 1: The Old Way (Manual Authentication Logic - Pre-Spring Security 5)

• Fighter: UsernamePasswordAuthenticationFilter (Goku in base form 🟡)
• Power Level: 5,000
• Fighting Style:
  • Old-school UsernamePasswordAuthenticationFilter was session-based.
  • Used HttpServletRequest.getParameter("username") to get credentials.
  • Relied on a session or SecurityContextHolder to track authentication state.
  • Could be extended, but customization required a lot of boilerplate code.

🔻 Weaknesses:

• Tied to Form-based login → Not great for APIs.
• Harder to customize authentication flows (e.g., extracting tokens from a custom header).
• Relies on session persistence → Not ideal for stateless applications.

🔥 Round 2: The New Way (Spring Security 5+ AuthenticationFilter - Super Saiyan Form!)

• Fighter: AuthenticationFilter (Super Saiyan Goku 🟠)
• Power Level: 9,000+
• Fighting Style:
  • More flexible! Supports multiple authentication methods (JWT, API keys, OAuth2, etc.).
  • Stateless by default → Perfect for microservices & APIs.
  • Extracts credentials from HttpServletRequest, but now via customizable AuthenticationConverter!
  • Supports modern authentication flows with less boilerplate.

⚡ Key Features:

✅ AuthenticationConverter → Extracts authentication details from requests flexibly.

✅ AuthenticationManager → Decouples authentication logic for better separation of concerns.

✅ Easier Customization → Can swap out token extraction logic without touching Spring internals.

🔺 Super Power (Advantages Over the Old Way):

• No session needed! Perfect for stateless applications.