序

对于使用spring security来说，存在一种需求，就是动态去配置url的权限，即在运行时去配置url对应的访问角色。这里简单介绍一下。

Standard Filter Aliases and Ordering

首先需要了解spring security内置的各种filter：

这里我们要操作的是FilterSecurityInterceptor这个interceptor，使用withObjectPostProcessor来设置

FilterSecurityInterceptor

这个filter有几个要素，如下：

• SecurityMetadataSource
• AccessDecisionManager
• AuthenticationManager

可以根据情况自己去重新设置，这里我们重写一下SecurityMetadataSource用来动态获取url权限配置，还有AccessDecisionManager来进行权限判断。

MyAccessDecisionManager

public class MyAccessDecisionManager implements org.springframework.security.access.AccessDecisionManager {

    @Override
    public void decide(Authentication authentication, Object object,
                       Collection<ConfigAttribute> configAttributes)
            throws AccessDeniedException, InsufficientAuthenticationException {
        //这段代码其实不需要,因为spring-security-core-4.1.4.RELEASE-sources.jar!/org/springframework/security/access/intercept/AbstractSecurityInterceptor.java第215行判断提前返回了,不会进入decide方法
        if (CollectionUtils.isEmpty(configAttributes)) {
            throw new AccessDeniedException("not allow");
        }
        Iterator<ConfigAttribute> ite = configAttributes.iterator();
        while (ite.hasNext()) {
            ConfigAttribute ca = ite.next();
            String needRole = ((org.springframework.security.access.SecurityConfig) ca).getAttribute();
            for (GrantedAuthority ga : authentication.getAuthorities()) {
                if(ga.getAuthority().equals(needRole)){
                    //匹配到有对应角色,则允许通过
                    return;
                }
            }
        }
        //该url有配置权限,但是当然登录用户没有匹配到对应权限,则禁止访问
        throw new AccessDeniedException("not allow");
    }
    @Override
    public boolean supports(ConfigAttribute attribute) {
        return true;
    }

    @Override
    public boolean supports(Class<?> clazz) {
        return true;
    }
}

这里遍历判断该url所需的角色看用户是否具备，有具备则返回，都不具备则抛出AccessDeniedException异常

MyFilterInvocationSecurityMetadataSource

public class MyFilterInvocationSecurityMetadataSource implements org.springframework.security.web.access.intercept.FilterInvocationSecurityMetadataSource {

    private final AntPathMatcher antPathMatcher = new AntPathMatcher();

    private final Map<String,String> urlRoleMap = new HashMap<String,String>(){{
        put("/open/**","ROLE_ANONYMOUS");
        put("/health","ROLE_ANONYMOUS");
        put("/restart","ROLE_ADMIN");
        put("/demo","ROLE_USER");
    }};

    @Override
    public Collection<ConfigAttribute> getAttributes(Object object) throws IllegalArgumentException {
        FilterInvocation fi = (FilterInvocation) object;
        String url = fi.getRequestUrl();
//        String httpMethod = fi.getRequest().getMethod();
        for(Map.Entry<String,String> entry:urlRoleMap.entrySet()){
            if(antPathMatcher.match(entry.getKey(),url)){
                return SecurityConfig.createList(entry.getValue());
            }
        }
        //没有匹配到,默认是要登录才能访问
        return SecurityConfig.createList("ROLE_USER");
//        return null;
    }

    @Override
    public Collection<ConfigAttribute> getAllConfigAttributes() {
        return null;
    }

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

这里以内存的map来展示一下，实际应用可以从分布式配置中心或者数据库中读取，另外循环遍历这个可能消耗性能，必要时得优化一下。

SecurityConfig

最后需要综合配置一下，如下

@EnableWebSecurity
public class SecurityConfig extends WebSecurityConfigurerAdapter {

    @Override
    public void configure(HttpSecurity http) throws Exception {
        http
                .authorizeRequests()
                .anyRequest().authenticated()
                .withObjectPostProcessor(new ObjectPostProcessor<FilterSecurityInterceptor>() {
                    public <O extends FilterSecurityInterceptor> O postProcess(
                            O fsi) {
                        fsi.setSecurityMetadataSource(mySecurityMetadataSource());
                        fsi.setAccessDecisionManager(myAccessDecisionManager());
                        return fsi;
                    }
                });
    }

    @Bean
    public FilterInvocationSecurityMetadataSource mySecurityMetadataSource() {
        MyFilterInvocationSecurityMetadataSource securityMetadataSource = new MyFilterInvocationSecurityMetadataSource();
        return securityMetadataSource;
    }

    @Bean
    public AccessDecisionManager myAccessDecisionManager() {
        return new MyAccessDecisionManager();
    }
}

doc

• spring-security-reference
• spring security使用数据库获取资源、角色和权限保护web应用
• spring security之用户 权限 url存储在数据库