Springsecurity之ExceptionTranslationFilter

	private void handleSpringSecurityException(HttpServletRequest request,
			HttpServletResponse response, FilterChain chain, RuntimeException exception)
			throws IOException, ServletException {
		if (exception instanceof AuthenticationException) {
			logger.debug(
					"Authentication exception occurred; redirecting to authentication entry point",
					exception);

			sendStartAuthentication(request, response, chain,
					(AuthenticationException) exception);
		}
		else if (exception instanceof AccessDeniedException) {
			Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
			if (authenticationTrustResolver.isAnonymous(authentication) || authenticationTrustResolver.isRememberMe(authentication)) {
				logger.debug(
						"Access is denied (user is " + (authenticationTrustResolver.isAnonymous(authentication) ? "anonymous" : "not fully authenticated") + "); redirecting to authentication entry point",
						exception);

				sendStartAuthentication(
						request,
						response,
						chain,
						new InsufficientAuthenticationException(
							messages.getMessage(
								"ExceptionTranslationFilter.insufficientAuthentication",
								"Full authentication is required to access this resource")));
			}
			else {
				logger.debug(
						"Access is denied (user is not anonymous); delegating to AccessDeniedHandler",
						exception);

				accessDeniedHandler.handle(request, response,
						(AccessDeniedException) exception);
			}
		}
	}

	protected void sendStartAuthentication(HttpServletRequest request,
			HttpServletResponse response, FilterChain chain,
			AuthenticationException reason) throws ServletException, IOException {
		// SEC-112: Clear the SecurityContextHolder's Authentication, as the
		// existing Authentication is no longer considered valid
		SecurityContextHolder.getContext().setAuthentication(null);
		requestCache.saveRequest(request, response);
		logger.debug("Calling Authentication entry point.");
		authenticationEntryPoint.commence(request, response, reason);
	}