intermediateSpring Security
What is UserDetailsService? How does Spring Security authenticate a user?
UsernamePasswordAuthenticationFilter extracts credentials, builds a token, and passes it to AuthenticationManager, which delegates to DaoAuthenticationProvider — that calls UserDetailsService.loadUserByUsername(), compares the password via PasswordEncoder.matches(), and on success sets the resulting Authentication into SecurityContext.
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What is UserDetailsService? How does Spring Security authenticate a user?