How does SpringBoot integrate SpringSecurityOauth2 to implement dynamic permission issues for authentication?

@PostConstruct
 public void init(){
        super.setAuthenticationManager(authenticationManager);
        super.setAccessDecisionManager(myAccessDecisionManager);
  }

@Override
public SecurityMetadataSource obtainSecurityMetadataSource() {
    return this.mySecurityMetadataSource;
}

/**
     * 获得当前请求所需要的角色
     * @param object
     * @return
     * @throws IllegalArgumentException
     */
    @Override
    public Collection<ConfigAttribute> getAttributes(Object object) throws IllegalArgumentException {
        String requestUrl = ((FilterInvocation) object).getRequestUrl();

        if (IS_CHANGE_SECURITY) {
            loadResourceDefine();
        }
        if (requestUrl.indexOf("?") > -1) {
            requestUrl = requestUrl.substring(0, requestUrl.indexOf("?"));
        }
        UrlPathMatcher matcher = new UrlPathMatcher();
        List<Object> list = new ArrayList<>();  //无需权限的，直接返回
        list.add("/oauth/**");
        list.add("/open/**");
        if(matcher.pathsMatchesUrl(list,requestUrl))
            return null;

        Set<String> roleNames = new HashSet();
        for (Resc resc: resources) {
            String rescUrl = resc.getResc_url();
            if (matcher.pathMatchesUrl(rescUrl, requestUrl)) {
                if(resc.getParent_resc_id() != null && resc.getParent_resc_id().intValue() == 1){   //默认权限的则只要登录了，无需权限匹配都可访问
                    roleNames = new HashSet();
                    break;
                }
                Map map = new HashMap();
                map.put("resc_id", resc.getResc_id());
                // 获取能访问该资源的所有权限(角色)
                List<RoleRescDTO> roles = roleRescMapper.findAll(map);
                for (RoleRescDTO rr : roles)
                    roleNames.add(rr.getRole_name());
            }
        }

        Set<ConfigAttribute> configAttributes = new HashSet();
        for(String roleName:roleNames)
            configAttributes.add(new SecurityConfig(roleName));

        log.debug("【所需的权限(角色)】:" + configAttributes);

        return configAttributes;
    }

@Override
    public void decide(Authentication authentication, Object o, Collection<ConfigAttribute> configAttributes) throws AccessDeniedException, InsufficientAuthenticationException {
        if(configAttributes == null){   //属于白名单的，不需要权限
            return;
        }
        Iterator<ConfigAttribute> iterator = configAttributes.iterator();
        while (iterator.hasNext()){
            ConfigAttribute configAttribute = iterator.next();
            String needPermission = configAttribute.getAttribute();
            for (GrantedAuthority ga: authentication.getAuthorities()) {
                if(needPermission.equals(ga.getAuthority())){   //有权限，可访问
                    return;
                }
            }
        }
        throw new AccessDeniedException("没有权限访问");

    }

@Override
    public void configure(ResourceServerSecurityConfigurer resources) throws Exception {
        resources.authenticationEntryPoint(authenticationEntryPoint)    //token失效或没携带token时
                .accessDeniedHandler(requestAccessDeniedHandler);   //权限不足时
    }

protected User user;
    public SecurityUser(User user) {
        this.user = user;
    }

    public User getUser() {
        return user;
    }

protected User getUser() {
        try {
            SecurityUser userDetails = (SecurityUser) SecurityContextHolder.getContext().getAuthentication()
                    .getPrincipal();

            User user = userDetails.getUser();
            log.debug("【用户:】:" + user);

            return user;
        } catch (Exception e) {
        }
        return null;
    }

@Service
public class TokenUserDetailsService implements UserDetailsService{

    @Autowired
    private LoginService loginService;

    @Override
    public UserDetails loadUserByUsername(String username) throws UsernameNotFoundException {
        User user = loginService.loadUserByUsername(username);  //这个我们拎出来处理
        if(Objects.isNull(user))
            throw new UsernameNotFoundException("用户名不存在");
        return new SecurityUser(user);
    }
}

@Override
    protected void configure(AuthenticationManagerBuilder auth) throws Exception {
        auth.userDetailsService(userDetailsService).passwordEncoder(passwordEncoder());
    }

@Override
    public User loadUserByUsername(String username){
        log.debug(username);
        Map map = new HashMap();
        map.put("username",username);
        map.put("is_deleted",-1);
        User user = userMapper.findByUsername(map);
        if(user != null){
            map = new HashMap();
            map.put("user_id",user.getUser_id());
            //查询用户的角色
            List<UserRoleDTO> userRoles = userRoleMapper.findAll(map);
            user.setRoles(listRoles(userRoles));
            //权限集合
            Collection<? extends GrantedAuthority> authorities = merge(userRoles);
            user.setAuthorities(authorities);
            return user;
        }
        return null;

    }