Spring Security源碼解析之權限訪問控制是如何做到的

abstract class AbstractInterceptUrlConfigurer<C extends AbstractInterceptUrlConfigurer<C, H>, H extends HttpSecurityBuilder<H>>
		extends AbstractHttpConfigurer<C, H> {
	...
	@Override
	public void configure(H http) throws Exception {
		FilterInvocationSecurityMetadataSource metadataSource = createMetadataSource(http);
		if (metadataSource == null) {
			return;
		}
		FilterSecurityInterceptor securityInterceptor = createFilterSecurityInterceptor(
				http, metadataSource, http.getSharedObject(AuthenticationManager.class));
		if (filterSecurityInterceptorOncePerRequest != null) {
			securityInterceptor
					.setObserveOncePerRequest(filterSecurityInterceptorOncePerRequest);
		}
		securityInterceptor = postProcess(securityInterceptor);
		http.addFilter(securityInterceptor);
		http.setSharedObject(FilterSecurityInterceptor.class, securityInterceptor);
	}
	...
}

public final class ExceptionHandlingConfigurer<H extends HttpSecurityBuilder<H>> extends
		AbstractHttpConfigurer<ExceptionHandlingConfigurer<H>, H> {
	...
	@Override
	public void configure(H http) throws Exception {
		AuthenticationEntryPoint entryPoint = getAuthenticationEntryPoint(http);
		ExceptionTranslationFilter exceptionTranslationFilter = new ExceptionTranslationFilter(
				entryPoint, getRequestCache(http));
		if (accessDeniedHandler != null) {
			exceptionTranslationFilter.setAccessDeniedHandler(accessDeniedHandler);
		}
		exceptionTranslationFilter = postProcess(exceptionTranslationFilter);
		http.addFilter(exceptionTranslationFilter);
	}
	...
}

protected InterceptorStatusToken beforeInvocation(Object object) {
		
		...

		// 獲取當前request請求所能匹配中的權限Spel表達式
		Collection<ConfigAttribute> attributes = this.obtainSecurityMetadataSource()
				.getAttributes(object);
				
		...

		// Attempt authorization
		try {
			this.accessDecisionManager.decide(authenticated, object, attributes);
		}
		catch (AccessDeniedException accessDeniedException) {
			publishEvent(new AuthorizationFailureEvent(object, attributes, authenticated,
					accessDeniedException));

			throw accessDeniedException;
		}
		
		...
		
	}

public void decide(Authentication authentication, Object object,
			Collection<ConfigAttribute> configAttributes) throws AccessDeniedException {
		int deny = 0;

		for (AccessDecisionVoter voter : getDecisionVoters()) {
			int result = voter.vote(authentication, object, configAttributes);

			if (logger.isDebugEnabled()) {
				logger.debug("Voter: " + voter + ", returned: " + result);
			}

			switch (result) {
			case AccessDecisionVoter.ACCESS_GRANTED:
				return;

			case AccessDecisionVoter.ACCESS_DENIED:
				deny++;

				break;

			default:
				break;
			}
		}

		if (deny > 0) {
			throw new AccessDeniedException(messages.getMessage(
					"AbstractAccessDecisionManager.accessDenied", "Access is denied"));
		}

		// To get this far, every AccessDecisionVoter abstained
		checkAllowIfAllAbstainDecisions();
	}

public int vote(Authentication authentication, FilterInvocation fi,
			Collection<ConfigAttribute> attributes) {
		assert authentication != null;
		assert fi != null;
		assert attributes != null;

		WebExpressionConfigAttribute weca = findConfigAttribute(attributes);

		if (weca == null) {
			return ACCESS_ABSTAIN;
		}

		EvaluationContext ctx = expressionHandler.createEvaluationContext(authentication,
				fi);
		ctx = weca.postProcess(ctx, fi);

		return ExpressionUtils.evaluateAsBoolean(weca.getAuthorizeExpression(), ctx) ? ACCESS_GRANTED
				: ACCESS_DENIED;
	}

private boolean hasAnyAuthorityName(String prefix, String... roles) {
		Set<String> roleSet = getAuthoritySet();

		for (String role : roles) {
			String defaultedRole = getRoleWithDefaultPrefix(prefix, role);
			if (roleSet.contains(defaultedRole)) {
				return true;
			}
		}

		return false;
	}

public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain)
			throws IOException, ServletException {
		HttpServletRequest request = (HttpServletRequest) req;
		HttpServletResponse response = (HttpServletResponse) res;

		try {
			chain.doFilter(request, response);

			logger.debug("Chain processed normally");
		}
		catch (IOException ex) {
			throw ex;
		}
		catch (Exception ex) {
			// Try to extract a SpringSecurityException from the stacktrace
			Throwable[] causeChain = throwableAnalyzer.determineCauseChain(ex);
			RuntimeException ase = (AuthenticationException) throwableAnalyzer
					.getFirstThrowableOfType(AuthenticationException.class, causeChain);

			if (ase == null) {
				ase = (AccessDeniedException) throwableAnalyzer.getFirstThrowableOfType(
						AccessDeniedException.class, causeChain);
			}

			if (ase != null) {
				handleSpringSecurityException(request, response, chain, ase);
			}
			else {
				// Rethrow ServletExceptions and RuntimeExceptions as-is
				if (ex instanceof ServletException) {
					throw (ServletException) ex;
				}
				else if (ex instanceof RuntimeException) {
					throw (RuntimeException) ex;
				}

				// Wrap other Exceptions. This shouldn't actually happen
				// as we've already covered all the possibilities for doFilter
				throw new RuntimeException(ex);
			}
		}
	}