public class AuthenticationFilter extends GenericFilterBean {

	@Override
	public void doFilter(ServletRequest request, ServletResponse response,
			FilterChain filterChain) throws IOException, ServletException{

		Authentication authentication = AuthenticationService
				.getAuthentication((HttpServletRequest)request);

		SecurityContextHolder.getContext()
			.setAuthentication(authentication);
		filterChain.doFilter(request, response);
	}
}

public class LoginFilter extends AbstractAuthenticationProcessingFilter {

	public LoginFilter(String url, AuthenticationManager authManager) {
		super(new AntPathRequestMatcher(url));
		setAuthenticationManager(authManager);
	}

	@Override
	public Authentication attemptAuthentication(HttpServletRequest request, HttpServletResponse response)
			throws AuthenticationException, IOException, ServletException {

		AccountCredentials creds = new ObjectMapper()
				.readValue(request.getInputStream(), AccountCredentials.class);

		return getAuthenticationManager().authenticate(
				new UsernamePasswordAuthenticationToken(
						creds.getUsername(),
						creds.getPassword(),
						Collections.emptyList()
				)
		);
	}

	@Override
	protected void successfulAuthentication(HttpServletRequest request, HttpServletResponse response, FilterChain chain,
			Authentication auth) throws IOException, ServletException {

		AuthenticationService.addToken(response, auth.getName());
	}
}

public class SecurityConfig extends WebSecurityConfigurerAdapter {

	@Autowired
	private UserDetailsServiceImpl userDetailsService;

	@Autowired
	public void configureGlobal(AuthenticationManagerBuilder auth) throws Exception{

		auth.userDetailsService(userDetailsService)
		.passwordEncoder(new BCryptPasswordEncoder());
	}

}