Spring Security4.0.3源码分析之http标签解析

最近在学习安全框架Spring Security,想弄清楚其中实现的具体步骤,于是下定决心,研究一下Spring Security源码,这篇博客的目的是想把学习过程记录下来。学习过程中主要参考了http://dead-knight.iteye.com/category/220917大神的博客,然后在其基础上,进行更详细的说明

在FilterChainProxy初始化的过程中,大概描述了标签解析的一些步骤,但是还不够详细,该篇博客将进行更细致的说明。HTTP标签的解析由HTTP标签解析类org.springframework.security.config.http.HttpSecurityBeanDefinitionParser完成

1.解析过程

public BeanDefinition parse(Element element, ParserContext pc) {
    CompositeComponentDefinition compositeDef = new CompositeComponentDefinition(element.getTagName(), pc.extractSource(element));
    pc.pushContainingComponent(compositeDef);

    // 创建了listFactoryBean实例和springSecurityFilterChain实例
    registerFilterChainProxyIfNecessary(pc, pc.extractSource(element));

    // 获取listFactoryBean实例
    BeanDefinition listFactoryBean = pc.getRegistry().getBeanDefinition(BeanIds.FILTER_CHAINS);
    List filterChains = (List) listFactoryBean.getPropertyValues().getPropertyValue("sourceList").getValue();

    // 创建过滤器链 移步2
    filterChains.add(createFilterChain(element, pc));

    pc.popAndRegisterContainingComponent();
    return null;
}

2.创建过滤器链

private BeanReference createFilterChain(Element element, ParserContext pc) {
    // 判断是否需要Security拦截
    boolean secured = !OPT_SECURITY_NONE.equals(element.getAttribute(ATT_SECURED));

    if (!secured) {
        // 如果没配置pattern属性并且配置了request-matcher-ref为空 添加错误信息
        if (!StringUtils.hasText(element.getAttribute(ATT_PATH_PATTERN)) && !StringUtils.hasText(ATT_REQUEST_MATCHER_REF)) {
            pc.getReaderContext().error("The '" + ATT_SECURED + "' attribute must be used in combination with" + " the '" + ATT_PATH_PATTERN + "' or '" + ATT_REQUEST_MATCHER_REF + "' attributes.", pc.extractSource(element));
        }

        for (int n = 0; n < element.getChildNodes().getLength(); n++) {
            // 如果有子节点则添加错误信息
            if (element.getChildNodes().item(n) instanceof Element) {
                pc.getReaderContext().error("If you are using  to define an unsecured pattern, " + "it cannot contain child elements.", pc.extractSource(element));
            }
        }

        // 创建过滤器链
        return createSecurityFilterChainBean(element, pc, Collections.emptyList());
    }

    // portMapper、portResolver主要提供给SSL相关类使用
    final BeanReference portMapper = createPortMapper(element, pc);
    final BeanReference portResolver = createPortResolver(portMapper, pc);

    // 新建一个空的authenticationProviders集合 
    ManagedList authenticationProviders = new ManagedList();
    // 通过空的authenticationProviders集合产生一个AuthenticationManager的bean定义
    BeanReference authenticationManager = createAuthenticationManager(element, pc, authenticationProviders);

    // 是否全采用默认配置
    boolean forceAutoConfig = isDefaultHttpConfig(element);
    // 详解移步3
    HttpConfigurationBuilder httpBldr = new HttpConfigurationBuilder(element, forceAutoConfig, pc, portMapper, portResolver, authenticationManager);
    // 详解移步4
    AuthenticationConfigBuilder authBldr = new AuthenticationConfigBuilder(element, forceAutoConfig, pc, httpBldr.getSessionCreationPolicy(), httpBldr.getRequestCache(), authenticationManager, httpBldr.getSessionStrategy(), portMapper, portResolver, httpBldr.getCsrfLogoutHandler());

    // 配置logoutHandlers
    httpBldr.setLogoutHandlers(authBldr.getLogoutHandlers());
    httpBldr.setEntryPoint(authBldr.getEntryPointBean());
    httpBldr.setAccessDeniedHandler(authBldr.getAccessDeniedHandlerBean());

    // 向AuthenticationProviders中添加provider  
    authenticationProviders.addAll(authBldr.getProviders());

    List unorderedFilterChain = new ArrayList();

    // 向FilterChain链中添加filters  
    unorderedFilterChain.addAll(httpBldr.getFilters());
    unorderedFilterChain.addAll(authBldr.getFilters());

    // 添加自定义的Filter，也就是custom-filter标签定义的Filter  
    unorderedFilterChain.addAll(buildCustomFilterList(element, pc));

    // 对过滤器进行排序
    Collections.sort(unorderedFilterChain, new OrderComparator());
    // 校验过滤器是否有效
    checkFilterChainOrder(unorderedFilterChain, pc, pc.extractSource(element));

    // The list of filter beans
    List filterChain = new ManagedList();

    for (OrderDecorator od : unorderedFilterChain) {
        filterChain.add(od.bean);
    }

    // 创建SecurityFilterChain 详情移步5
    return createSecurityFilterChainBean(element, pc, filterChain);
}

3.HttpConfigurationBuilder

public HttpConfigurationBuilder(Element element, boolean addAllAuth, ParserContext pc, BeanReference portMapper, BeanReference portResolver, BeanReference authenticationManager) {
    this.httpElt = element;
    this.addAllAuth = addAllAuth;
    this.pc = pc;
    this.portMapper = portMapper;
    this.portResolver = portResolver;
    this.matcherType = MatcherType.fromElement(element);
    // 获取子标签intercept-url
    interceptUrls = DomUtils.getChildElementsByTagName(element, Elements.INTERCEPT_URL);

    for (Element urlElt : interceptUrls) {
        // 判断子标签intercept-url是否配置了filters属性
        // 如果配置了filters属性添加错误消息,因为Security已经不再支持filters属性了
        if (StringUtils.hasText(urlElt.getAttribute(ATT_FILTERS))) {
            pc.getReaderContext().error("The use of \"filters='none'\" is no longer supported. Please define a" + " separate  element for the pattern you want to exclude and use the attribute" + " \"security='none'\".", pc.extractSource(urlElt));
        }
    }

    // 获取标签create-session属性
    String createSession = element.getAttribute(ATT_CREATE_SESSION);

    if (StringUtils.hasText(createSession)) {
        sessionPolicy = createPolicy(createSession);
    } else {
        // 默认策略
        sessionPolicy = SessionCreationPolicy.IF_REQUIRED;
    }

    // 创建一系列过滤器
    createCsrfFilter();
    createSecurityContextPersistenceFilter();
    createSessionManagementFilters();
    createWebAsyncManagerFilter();
    createRequestCacheFilter();
    createServletApiFilter(authenticationManager);
    createJaasApiFilter();
    createChannelProcessingFilter();
    createFilterSecurityInterceptor(authenticationManager);
    createAddHeadersFilter();
}

4.AuthenticationConfigBuilder

public AuthenticationConfigBuilder(Element element, boolean forceAutoConfig, ParserContext pc, SessionCreationPolicy sessionPolicy, BeanReference requestCache, BeanReference authenticationManager, BeanReference sessionStrategy, BeanReference portMapper, BeanReference portResolver, BeanMetadataElement csrfLogoutHandler) {
    this.httpElt = element;
    this.pc = pc;
    this.requestCache = requestCache;
    // 是否自动配置
    autoConfig = forceAutoConfig | "true".equals(element.getAttribute(ATT_AUTO_CONFIG));
    // 是否允许session
    this.allowSessionCreation = sessionPolicy != SessionCreationPolicy.NEVER && sessionPolicy != SessionCreationPolicy.STATELESS;
    this.portMapper = portMapper;
    this.portResolver = portResolver;
    this.csrfLogoutHandler = csrfLogoutHandler;

    // 创建一系列过滤器
    createAnonymousFilter();
    createRememberMeFilter(authenticationManager);
    createBasicFilter(authenticationManager);
    createFormLoginFilter(sessionStrategy, authenticationManager);
    createOpenIDLoginFilter(sessionStrategy, authenticationManager);
    createX509Filter(authenticationManager);
    createJeeFilter(authenticationManager);
    createLogoutFilter();
    createLoginPageFilterIfNeeded();
    createUserDetailsServiceFactory();
    createExceptionTranslationFilter();
}

5.创建SecurityFilterChain

private BeanReference createSecurityFilterChainBean(Element element, ParserContext pc, List filterChain) {
    BeanMetadataElement filterChainMatcher;

    String requestMatcherRef = element.getAttribute(ATT_REQUEST_MATCHER_REF);
    String filterChainPattern = element.getAttribute(ATT_PATH_PATTERN);

    // 实例化filterChainMatcher
    if (StringUtils.hasText(requestMatcherRef)) {
        if (StringUtils.hasText(filterChainPattern)) {
            // 不能在配置了request-matcher-ref的同时配置pattern
            pc.getReaderContext().error("You can't define a pattern and a request-matcher-ref for the " + "same filter chain", pc.extractSource(element));
        }
        filterChainMatcher = new RuntimeBeanReference(requestMatcherRef);
    }else if (StringUtils.hasText(filterChainPattern)) {
        filterChainMatcher = MatcherType.fromElement(element).createMatcher(filterChainPattern, null);
    }else {
        filterChainMatcher = new RootBeanDefinition(AnyRequestMatcher.class);
    }

    BeanDefinitionBuilder filterChainBldr = BeanDefinitionBuilder.rootBeanDefinition(DefaultSecurityFilterChain.class);
    filterChainBldr.addConstructorArgValue(filterChainMatcher);
    filterChainBldr.addConstructorArgValue(filterChain);

    BeanDefinition filterChainBean = filterChainBldr.getBeanDefinition();

    // 获取http标签的name属性
    String id = element.getAttribute("name");
    if (!StringUtils.hasText(id)) {
        id = element.getAttribute("id");
        if (!StringUtils.hasText(id)) {
            // 生成ID
            id = pc.getReaderContext().generateBeanName(filterChainBean);
        }
    }

    // 注册DefaultSecurityFilterChain
    pc.registerBeanComponent(new BeanComponentDefinition(filterChainBean, id));

    return new RuntimeBeanReference(id);
}

至此,大概HTTP标签的解析已经差不多了,虽然每个Filter的BeanDefinition创建过程还没有一一细说,但基本步骤如下：

1.通过Filter的类路径获取BeanDefinitionBuilder对象,如BeanDefinitionBuilder filterBuilder = BeanDefinitionBuilder.rootBeanDefinition(filterClassName)

2.解析xml标签属性,再通过BeanDefinitionBuilder的addPropertyValue,addPropertyReference等方法设置Filter对应BeanDefinition的属性值,依赖bean 

3.注册BeanDefinition。通过ParserContext.registerBeanComponent(new BeanComponentDefinition(BeanDefinition,beanId));完成bean的注册,还可以通过ParserContext.getRegistry().registerAlias方法注册bean的别名 

实际上,标签解析就是构造BeanDefinition,然后注册到beanfactory中,而BeanDefinition就是Spring中定义bean的数据结构