Spring Security实现基于RBAC的权限表达式动态访问控制的操作方法

基于RBAC的权限表达式动态访问控制是Spring Security中常用的一种权限控制方式。以下是具体的实现方法：

1. 定义RBAC模型

可参考以下示例：

### 角色
1. 管理员
2. 普通用户

### 权限
1. 用户管理：创建、删除用户
2. 文章管理：查看、修改、删除所有文章；创建、修改、删除自己的文章

### 资源
- 用户: /user/**
- 文章: /article/**

2. 实现自定义AccessDecisionManager

继承于AbstractAccessDecisionManager并实现decide()方法。其中，自定义的AccessDecisionManager需要获取到当前用户的所有角色和请求所需要的权限，然后判断用户所拥有的角色中是否有权限，决定用户是否可以访问特定的请求。

方法参数说明：

• authentication：当前登录用户的身份验证对象（即spring security的Authentication对象）
• object：封装了请求信息（如请求URL），可以通过它来判断用户请求的资源
• configAttributes：可以获取到访问某个资源所需要的角色

可参考以下示例：

@Component
public class CustomAccessDecisionManager extends AbstractAccessDecisionManager {

    private final UserService userService;

    public CustomAccessDecisionManager(UserService userService,
                                       List<AccessDecisionVoter<?>> decisionVoters) {
        super(decisionVoters);
        this.userService = userService;
    }

    @Override
    public void decide(Authentication authentication, Object object, Collection<ConfigAttribute> configAttributes)
            throws AccessDeniedException, InsufficientAuthenticationException {
        // 判断当前用户是否已登录
        if (authentication == null || !authentication.isAuthenticated()) {
            throw new AccessDeniedException("当前用户未登录");
        }

        // 获取当前用户所拥有的角色
        List<Role> userRoles = userService.getUserRoles(authentication.getName());
        if (userRoles == null || userRoles.isEmpty()) {
            throw new AccessDeniedException("当前用户未分配角色");
        }

        // 获取当前请求需要的角色
        Collection<String> requiredRoles = getRequiredRoles(configAttributes);
        if (requiredRoles == null || requiredRoles.isEmpty()) {
            throw new AccessDeniedException("当前请求未配置权限");
        }

        // 判断当前用户所拥有的角色和当前请求所需的角色是否匹配
        boolean isAuthorized = userRoles.stream()
                .map(Role::getRoleName)
                .anyMatch(requiredRoles::contains);
        if (!isAuthorized) {
            throw new AccessDeniedException("当前用户无权访问");
        }
    }

    private Collection<String> getRequiredRoles(Collection<ConfigAttribute> configAttributes) {
        if (configAttributes == null || configAttributes.isEmpty()) {
            return null;
        }
        return configAttributes.stream()
                .map(ConfigAttribute::getAttribute)
                .collect(Collectors.toList());
    }
}

3. 实现自定义Security MetadataSource

继承于FilterInvocationSecurityMetadataSource并实现getAttributes()和supports()方法。其中，getAttributes()方法需要根据请求的URL返回该请求需要的角色，而supports()方法必须返回true。之后将该MetadataSource注入到Spring容器中。

可参考以下示例：

@Component
public class CustomInvocationSecurityMetadataSource extends AbstractSecurityInterceptor implements Filter {

    private final CustomAccessDecisionManager customAccessDecisionManager;

    public CustomInvocationSecurityMetadataSource(CustomAccessDecisionManager customAccessDecisionManager,
                                                   FilterInvocationSecurityMetadataSource metadataSource) {
        super();
        this.customAccessDecisionManager = customAccessDecisionManager;
        setAccessDecisionManager(customAccessDecisionManager);
        setSecurityMetadataSource(metadataSource);
    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
            throws IOException, ServletException {
        FilterInvocation filterInvocation = new FilterInvocation(request, response, chain);
        // 调用父类的beforeInvocation进行访问控制
        super.invoke(filterInvocation);
    }

    @Override
    public Class<?> getSecureObjectClass() {
        return FilterInvocation.class;
    }

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

    @Override
    public void destroy() {}

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {}

    @Override
    public boolean supports(Class<?> clazz) {
        return FilterInvocation.class.isAssignableFrom(clazz);
    }
}

4. 配置Spring Security

对Spring Security进行自定义配置，将CustomAccessDecisionManager和CustomInvocationSecurityMetadataSource注册到Security配置中。

可参考以下示例：

@Configuration
@EnableWebSecurity
public class SecurityConfig extends WebSecurityConfigurerAdapter {

    private final CustomAccessDecisionManager customAccessDecisionManager;
    private final FilterInvocationSecurityMetadataSource metadataSource;

    public SecurityConfig(CustomAccessDecisionManager customAccessDecisionManager,
                          FilterInvocationSecurityMetadataSource metadataSource) {
        this.customAccessDecisionManager = customAccessDecisionManager;
        this.metadataSource = metadataSource;
    }

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        /**
         * 为了演示方便，这里省略了其他配置
         */
        http.authorizeRequests()
            .anyRequest()
            .access("@customInvocationSecurityMetadataSource.decide(request,authentication)");
    }

    @Override
    protected void configure(AuthenticationManagerBuilder auth) throws Exception {
        /**
         * 为了演示方便，这里省略了其他配置
         */
        auth.userDetailsService(userDetailsService());
    }

    @Bean
    public CustomAccessDecisionManager customAccessDecisionManager(UserService userService) {
        List<AccessDecisionVoter<?>> voters = Arrays.asList(
                new RoleVoter(),
                new AuthenticatedVoter(),
                new WebExpressionVoter()
        );
        return new CustomAccessDecisionManager(userService, voters);
    }

    @Bean
    public FilterInvocationSecurityMetadataSource customInvocationSecurityMetadataSource() throws Exception {
        UrlFilterInvocationSecurityMetadataSource metadataSource = new UrlFilterInvocationSecurityMetadataSource(
                securityInterceptor().getSecurityMetadataSource(), new PatternMatcher());
        // 用户 -> 角色 -> 权限
        metadataSource.addSecurityMapping(new SecurityMapping("/user/**", "ROLE_ADMIN"));
        metadataSource.addSecurityMapping(new SecurityMapping("/article/**", "ROLE_USER", "ROLE_ADMIN"));
        return metadataSource;
    }

    @Bean
    public CustomInvocationSecurityMetadataSource customInvocationSecurityMetadataSource(
            CustomAccessDecisionManager customAccessDecisionManager,
            FilterInvocationSecurityMetadataSource metadataSource
    ) {
        return new CustomInvocationSecurityMetadataSource(customAccessDecisionManager, metadataSource);
    }

    @Bean
    public SecurityInterceptor securityInterceptor() {
        return new SecurityInterceptor();
    }
}

示例说明

示例一：

当前用户为管理员，请求URL为/user/delete，则可以完成对当前用户的删除操作。若请求URL为/article/create则不能创建文章。

示例二：

当前用户为普通用户，请求URL为/user/create，则无法完成对其他用户创建的用户进行创建。但是可以通过请求URL/article/update来完成自己的文章修改。

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