Java中AuthorizationFilter过滤器的功能

public class AuthorizationFilter extends GenericFilterBean {

   ...
   private final AuthorizationManager<HttpServletRequest> authorizationManager;

   

   /**
    * Creates an instance.
    * @param authorizationManager the {@link AuthorizationManager} to use
    */
   public AuthorizationFilter(AuthorizationManager<HttpServletRequest> authorizationManager) {
      Assert.notNull(authorizationManager, "authorizationManager cannot be null");
      this.authorizationManager = authorizationManager;
   }

   @Override
   public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain chain)
         throws ServletException, IOException {

      HttpServletRequest request = (HttpServletRequest) servletRequest;
      HttpServletResponse response = (HttpServletResponse) servletResponse;

      if (this.observeOncePerRequest && isApplied(request)) {
         chain.doFilter(request, response);
         return;
      }

      if (skipDispatch(request)) {
         chain.doFilter(request, response);
         return;
      }

      String alreadyFilteredAttributeName = getAlreadyFilteredAttributeName();
      request.setAttribute(alreadyFilteredAttributeName, Boolean.TRUE);
      try {
         //授权决策
         AuthorizationDecision decision = this.authorizationManager.check(this::getAuthentication, request);
         this.eventPublisher.publishAuthorizationEvent(this::getAuthentication, request, decision);
         if (decision != null && !decision.isGranted()) {
            throw new AccessDeniedException("Access Denied");
         }
         chain.doFilter(request, response);
      }
      finally {
         request.removeAttribute(alreadyFilteredAttributeName);
      }
   }

//授权决策
AuthorizationDecision decision = this.authorizationManager.check(this::getAuthentication, request);

@FunctionalInterface
public interface AuthorizationManager<T> {

   /**
    * Determines if access should be granted for a specific authentication and object.
    * @param authentication the {@link Supplier} of the {@link Authentication} to check
    * @param object the {@link T} object to check
    * @throws AccessDeniedException if access is not granted
    */
   default void verify(Supplier<Authentication> authentication, T object) {
      AuthorizationDecision decision = check(authentication, object);
      if (decision != null && !decision.isGranted()) {
         throw new AccessDeniedException("Access Denied");
      }
   }

   /**
    * Determines if access is granted for a specific authentication and object.
    * @param authentication the {@link Supplier} of the {@link Authentication} to check
    * @param object the {@link T} object to check
    * @return an {@link AuthorizationDecision} or null if no decision could be made
    */
   @Nullable
   AuthorizationDecision check(Supplier<Authentication> authentication, T object);

}

    public class AuthorizationDecision implements AuthorizationResult {

   private final boolean granted;

   public AuthorizationDecision(boolean granted) {
      this.granted = granted;
   }

   @Override
   public boolean isGranted() {
      return this.granted;
   }

   @Override
   public String toString() {
      return getClass().getSimpleName() + " [granted=" + this.granted + "]";
   }

}
    

public final class RequestMatcherDelegatingAuthorizationManager implements AuthorizationManager<HttpServletRequest> {

   private static final AuthorizationDecision DENY = new AuthorizationDecision(false);

   private final List<RequestMatcherEntry<AuthorizationManager<RequestAuthorizationContext>>> mappings;

/**
 * A rich object for associating a {@link RequestMatcher} to another object.
 * 从注释中可以看出RequestMatcherEntry就是用来将RequestMatcher和其他对象建立关联的
 * @author Marcus Da Coregio
 * @since 5.5.5
 */
public class RequestMatcherEntry<T> {

   private final RequestMatcher requestMatcher;

   private final T entry;

   public RequestMatcherEntry(RequestMatcher requestMatcher, T entry) {
      this.requestMatcher = requestMatcher;
      this.entry = entry;
   }

   public RequestMatcher getRequestMatcher() {
      return this.requestMatcher;
   }

   public T getEntry() {
      return this.entry;
   }

}

/**
 * Delegates to a specific {@link AuthorizationManager} based on a
 * {@link RequestMatcher} evaluation.
 * @param authentication the {@link Supplier} of the {@link Authentication} to check
 * @param request the {@link HttpServletRequest} to check
 * @return an {@link AuthorizationDecision}. If there is no {@link RequestMatcher}
 * matching the request, or the {@link AuthorizationManager} could not decide, then
 * null is returned
 */
@Override
public AuthorizationDecision check(Supplier<Authentication> authentication, HttpServletRequest request) {
   if (this.logger.isTraceEnabled()) {
      this.logger.trace(LogMessage.format("Authorizing %s", requestLine(request)));
   }
   for (RequestMatcherEntry<AuthorizationManager<RequestAuthorizationContext>> mapping : this.mappings) {

      RequestMatcher matcher = mapping.getRequestMatcher();
      MatchResult matchResult = matcher.matcher(request);
      if (matchResult.isMatch()) {
         AuthorizationManager<RequestAuthorizationContext> manager = mapping.getEntry();
         if (this.logger.isTraceEnabled()) {
            this.logger.trace(
                  LogMessage.format("Checking authorization on %s using %s", requestLine(request), manager));
         }
         return manager.check(authentication,
               new RequestAuthorizationContext(request, matchResult.getVariables()));
      }
   }
   if (this.logger.isTraceEnabled()) {
      this.logger.trace(LogMessage.of(() -> "Denying request since did not find matching RequestMatcher"));
   }
   return DENY;
}

@Bean
public SecurityFilterChain defaultSecurityFilterChain(HttpSecurity http)
        throws Exception {
    System.out.println("filterChain http: " + System.identityHashCode(http));
    http
            .authorizeHttpRequests((authorize) -> authorize
                    .requestMatchers("/admin/**").hasRole("ADMIN")
                    .anyRequest().authenticated()
            );
           

    return http.build();
}

    if (decision != null && !decision.isGranted()) { throw new AccessDeniedException("Access Denied"); }