SpringSecurity实现动态加载权限信息的方法

①数据库中资源与角色对应关系，以及角色和用户对应关系如下图所示：

 ②实现FilterInvocationSecurityMetadataSource类

(1)List<Menu> menus = menuService.getMenusWithRoles();这个是你自己的资源对应角色的查询方法。

(2)重写的support方法都返回true

@Configuration
public class MyFilterInvocation implements FilterInvocationSecurityMetadataSource {
 
    @Autowired
    private MenuService menuService;
 
    AntPathMatcher antPathMatcher = new AntPathMatcher();
 
    @Override
    public Collection<ConfigAttribute> getAttributes(Object object) throws IllegalArgumentException {
        String requestUrl = ((FilterInvocation) object).getRequestUrl();
        List<Menu> menus = menuService.getMenusWithRoles();
        //- 遍历数据库的url，看请求路径是否与其匹配
        for (Menu menu : menus) {
            //- 如果请求路径和数据库的路径匹配
            if (antPathMatcher.match(menu.getUrl(),requestUrl)){
                //- 访问该路径需要的角色
                List<Role> roles = menu.getRoles();
                String[] strs = new String[roles.size()];
                for (int i = 0; i < roles.size(); i++) {
                    strs[i] = roles.get(i).getName();
                }
                return SecurityConfig.createList(strs);
            }
        }
        //- 如果请求路径和数据库的所有路径都不匹配，说明这个资源是登录后即可访问的
        //- 用户登录即可访问,相当于在SecurityConfig中配置了.anyRequest().authenticated()
        return SecurityConfig.createList("ROLE_LOGIN");
    }
 
    @Override
    public Collection<ConfigAttribute> getAllConfigAttributes() {
        return null;
    }
 
    @Override
    public boolean supports(Class<?> clazz) {
        return true;
    }
}

③实现AccessDecisionManager类

重写的support方法都返回true

@Configuration
public class MyDecisionManager implements AccessDecisionManager {
 
 
    @Override
    public void decide(Authentication authentication, Object object, Collection<ConfigAttribute> configAttributes) throws AccessDeniedException, InsufficientAuthenticationException {
        for (ConfigAttribute configAttribute : configAttributes) {
            String needRole = configAttribute.getAttribute();
            if ("ROLE_LOGIN".equals(needRole)) {
                //- 用户登录即可访问,相当于在SecurityConfig中配置了.anyRequest().authenticated()
                if (authentication instanceof AnonymousAuthenticationToken) {
                    throw new AccessDeniedException("尚未登录，请先登录");
                } else {
                    return;
                }
            }
            
            Collection<? extends GrantedAuthority> authorities = authentication.getAuthorities();
            //这里我写的是只要访问该资源的用户具有`访问该资源所需要角色`的其中一个即可
            for (GrantedAuthority authority : authorities) {
                if (authority.getAuthority().equals(needRole)) {
                    return;
                }
            }
        }
        throw new AccessDeniedException("权限不足，请联系管理员");
    }
 
    @Override
    public boolean supports(ConfigAttribute attribute) {
        return true;
    }
 
    @Override
    public boolean supports(Class<?> clazz) {
        return true;
    }
}

④到SecurityConfig配置类中完成相应配置

    @Autowired
    private MyDecisionManager myDecisionManager;
    
    @Autowired
    private  MyFilterInvocation myFilterInvocation;
 
     @Override
    protected void configure(HttpSecurity http) throws Exception {
        http.authorizeRequests()
                .withObjectPostProcessor(new ObjectPostProcessor<FilterSecurityInterceptor>() {
                    @Override
                    public <O extends FilterSecurityInterceptor> O postProcess(O object) {
                        object.setAccessDecisionManager(myDecisionManager);
                        object.setSecurityMetadataSource(myFilterInvocation);
                        return object;
                    }
                });
 
            http.exceptionHandling().accessDeniedHandler(myAccessDeniedHandler());
 
    }
 
 
    @Bean
    MyAccessDeniedHandler myAccessDeniedHandler(){
        return new MyAccessDeniedHandler();
    }

⑤可选，实现AccessDeniedHandler类

public class MyAccessDenied implements AccessDeniedHandler {
 
    @Override
    public void handle(HttpServletRequest req, HttpServletResponse resp, AccessDeniedException accessDeniedException) throws IOException, ServletException {
        resp.setContentType("application/json;charset=utf-8");
        PrintWriter pw = resp.getWriter();
        pw.write(new ObjectMapper().writeValueAsString(RespBean.error("权限不够，请联系管理员")));
        pw.flush();
        pw.close();
    }
}