Spring Security3源码分析-FilterChainProxy初始化

程序员文章站 2022-04-26 11:41:49

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很久没有更新博客了，最近对Spring Security做了比较深入的研究。
spring security的教程网上很多：
http://lengyun3566.iteye.com/category/153689
http://wenku.baidu.com/view/b0c0dc0b79563c1ec5da7179.html

以上教程足够应付在实际项目中使用spring security这一安全框架了。如果想深入研究下，网上的资料就很少了，比如：
http://www.blogjava.net/SpartaYew/archive/2011/05/19/spingsecurity3.html
http://www.blogjava.net/youxia/archive/2008/12/07/244883.html
http://www.cnblogs.com/hzhuxin/archive/2011/12/19/2293730.html

但还是没有从filter配置开始进行一步一步分析。
带着很多疑问，逐步拨开spring security3的面纱
spring security在web.xml中的配置为

    <filter>
        <filter-name>springSecurityFilterChain</filter-name>
        <filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>springSecurityFilterChain</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>

一看就知道，这是spring的类，这个类位于org.springframework.web-3.0.1.RELEASE.jar这个jar下面，说明这个类本身是和springSecurity无关。DelegatingFilterProxy类继承于抽象类GenericFilterBean,间接地实现了javax.servlet.Filter接口。细节方面就不一一讲述了。看doFilter方法

	public void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain)
			throws ServletException, IOException {

		// Lazily initialize the delegate if necessary.
		Filter delegateToUse = null;
		synchronized (this.delegateMonitor) {
			if (this.delegate == null) {
				WebApplicationContext wac = findWebApplicationContext();
				if (wac == null) {
					throw new IllegalStateException("No WebApplicationContext found: no ContextLoaderListener registered?");
				}
				this.delegate = initDelegate(wac);
			}
			delegateToUse = this.delegate;
		}

		// Let the delegate perform the actual doFilter operation.
		invokeDelegate(delegateToUse, request, response, filterChain);
	}

这里做了两件事：
一、initDelegate(wac);//初始化FilterChainProxy

	protected Filter initDelegate(WebApplicationContext wac) throws ServletException {
		Filter delegate = wac.getBean(getTargetBeanName(), Filter.class);
		if (isTargetFilterLifecycle()) {
			delegate.init(getFilterConfig());
		}
		return delegate;
	}

getTargetBeanName()返回的是Filter的name:springSecurityFilterChain
Filter delegate = wac.getBean(getTargetBeanName(), Filter.class);
这里根据springSecurityFilterChain的bean name直接获取FilterChainProxy的实例。
这里大家会产生疑问，springSecurityFilterChain这个bean在哪里定义的呢？
此时似乎忽略了spring security的bean配置文件了

<?xml version="1.0" encoding="UTF-8"?>
<beans:beans xmlns="http://www.springframework.org/schema/security"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:beans="http://www.springframework.org/schema/beans"
       xsi:schemaLocation="
       http://www.springframework.org/schema/beans
       http://www.springframework.org/schema/beans/spring-beans.xsd
       http://www.springframework.org/schema/security
       http://www.springframework.org/schema/security/ 
              spring-security-3.0.xsd">
  <http auto-config="true">
    <intercept-url pattern="/*" access="ROLE_USER"/>
  </http>
  <authentication-manager alias="authenticationManager">
    <authentication-provider>
      <user-service>
        <user authorities="ROLE_USER" name="guest" password="guest"/>
      </user-service>
    </authentication-provider>
  </authentication-manager> 
</beans:beans>

这是最简单的配置了，同时也是解开springSecurityFilterChain这个bean没有定义的疑问了。
这里主要利用了spring的自定义标签。具体参见：
[url] http://www.w3school.com.cn/schema/schema_example.asp[/url]
首先spring security的标签解析部分的源码包为：
spring-security-config-3.0.2.RELEASE.jar
这个jar包的META-INF目录下面有spring.handlers,spring.schemas两个文件，其中spring.schemas文件主要是标签的规范、约束；而spring.handlers这个文件时真正解析自定义标签的类，这个文件的内容为：

http\://www.springframework.org/schema/security=org.springframework.security.config.SecurityNamespaceHandler

从这里可以看出来spring security的标签解析由org.springframework.security.config.SecurityNamespaceHandler
来处理。该类实现接口：NamespaceHandler，spring中自定义标签都要实现该接口，这个接口有三个方法init、parse、decorate，其中init用于自定义标签的初始化，parse用于解析标签，decorate用于装饰。
SecurityNamespaceHandler类的init方法完成了标签解析类的注册工作

    public void init() {
        // Parsers
        parsers.put(Elements.LDAP_PROVIDER, new LdapProviderBeanDefinitionParser());
        parsers.put(Elements.LDAP_SERVER, new LdapServerBeanDefinitionParser());
        parsers.put(Elements.LDAP_USER_SERVICE, new LdapUserServiceBeanDefinitionParser());
        parsers.put(Elements.USER_SERVICE, new UserServiceBeanDefinitionParser());
        parsers.put(Elements.JDBC_USER_SERVICE, new JdbcUserServiceBeanDefinitionParser());
        parsers.put(Elements.AUTHENTICATION_PROVIDER, new AuthenticationProviderBeanDefinitionParser());
        parsers.put(Elements.GLOBAL_METHOD_SECURITY, new GlobalMethodSecurityBeanDefinitionParser());
        parsers.put(Elements.AUTHENTICATION_MANAGER, new AuthenticationManagerBeanDefinitionParser());
 //       registerBeanDefinitionDecorator(Elements.INTERCEPT_METHODS, new InterceptMethodsBeanDefinitionDecorator());

        // Only load the web-namespace parsers if the web classes are available
        if (ClassUtils.isPresent("org.springframework.security.web.FilterChainProxy", getClass().getClassLoader())) {
            parsers.put(Elements.HTTP, new HttpSecurityBeanDefinitionParser());
            parsers.put(Elements.FILTER_INVOCATION_DEFINITION_SOURCE, new FilterInvocationSecurityMetadataSourceParser());
            parsers.put(Elements.FILTER_SECURITY_METADATA_SOURCE, new FilterInvocationSecurityMetadataSourceParser());
            filterChainMapBDD = new FilterChainMapBeanDefinitionDecorator();
            //registerBeanDefinitionDecorator(Elements.FILTER_CHAIN_MAP, new FilterChainMapBeanDefinitionDecorator());
        }
    }

可以看出，http的标签解析类注册代码为：

parsers.put(Elements.HTTP, new HttpSecurityBeanDefinitionParser());

authentication-manager的标签解析类注册代码为：

parsers.put(Elements.AUTHENTICATION_MANAGER, new AuthenticationManagerBeanDefinitionParser());

HttpSecurityBeanDefinitionParser的parse方法源码为：

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

        final String portMapperName = createPortMapper(element, pc);
        final UrlMatcher matcher = createUrlMatcher(element);

        HttpConfigurationBuilder httpBldr = new HttpConfigurationBuilder(element, pc, matcher, portMapperName);

        httpBldr.parseInterceptUrlsForEmptyFilterChains();
        httpBldr.createSecurityContextPersistenceFilter();
        httpBldr.createSessionManagementFilters();

        ManagedList<BeanReference> authenticationProviders = new ManagedList<BeanReference>();
        BeanReference authenticationManager = createAuthenticationManager(element, pc, authenticationProviders, null);

        httpBldr.createServletApiFilter();
        httpBldr.createChannelProcessingFilter();
        httpBldr.createFilterSecurityInterceptor(authenticationManager);

        AuthenticationConfigBuilder authBldr = new AuthenticationConfigBuilder(element, pc,
                httpBldr.isAllowSessionCreation(), portMapperName);

        authBldr.createAnonymousFilter();
        authBldr.createRememberMeFilter(authenticationManager);
        authBldr.createRequestCache();
        authBldr.createBasicFilter(authenticationManager);
        authBldr.createFormLoginFilter(httpBldr.getSessionStrategy(), authenticationManager);
        authBldr.createOpenIDLoginFilter(httpBldr.getSessionStrategy(), authenticationManager);
        authBldr.createX509Filter(authenticationManager);
        authBldr.createLogoutFilter();
        authBldr.createLoginPageFilterIfNeeded();
        authBldr.createUserServiceInjector();
        authBldr.createExceptionTranslationFilter();

        List<OrderDecorator> unorderedFilterChain = new ArrayList<OrderDecorator>();

        unorderedFilterChain.addAll(httpBldr.getFilters());
        unorderedFilterChain.addAll(authBldr.getFilters());

        authenticationProviders.addAll(authBldr.getProviders());

        BeanDefinition requestCacheAwareFilter = new RootBeanDefinition(RequestCacheAwareFilter.class);
        requestCacheAwareFilter.getPropertyValues().addPropertyValue("requestCache", authBldr.getRequestCache());
        unorderedFilterChain.add(new OrderDecorator(requestCacheAwareFilter, REQUEST_CACHE_FILTER));

        unorderedFilterChain.addAll(buildCustomFilterList(element, pc));

        Collections.sort(unorderedFilterChain, new OrderComparator());
        checkFilterChainOrder(unorderedFilterChain, pc, source);

        List<BeanMetadataElement> filterChain = new ManagedList<BeanMetadataElement>();

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

        ManagedMap<BeanDefinition, List<BeanMetadataElement>> filterChainMap = httpBldr.getFilterChainMap();
        BeanDefinition universalMatch = new RootBeanDefinition(String.class);
        universalMatch.getConstructorArgumentValues().addGenericArgumentValue(matcher.getUniversalMatchPattern());
        filterChainMap.put(universalMatch, filterChain);

        registerFilterChainProxy(pc, filterChainMap, matcher, source);

        pc.popAndRegisterContainingComponent();
        return null;
    }

很多spring security的教程都会说http标签配置了auto-config="true"属性，spring security就会自动配置好了过滤器链。但是这些过滤器是如何添加到链中的呢，教程没说。
但是上面的代码已经告诉我们，就在这里设置的

        httpBldr.createSecurityContextPersistenceFilter();
        httpBldr.createSessionManagementFilters();
        httpBldr.createServletApiFilter();
        httpBldr.createChannelProcessingFilter();
        httpBldr.createFilterSecurityInterceptor(authenticationManager);
        …………
        authBldr.createAnonymousFilter();
        authBldr.createRememberMeFilter(authenticationManager);
        authBldr.createRequestCache();
        authBldr.createBasicFilter(authenticationManager);
        authBldr.createFormLoginFilter(httpBldr.getSessionStrategy(), authenticationManager);
        authBldr.createOpenIDLoginFilter(httpBldr.getSessionStrategy(), authenticationManager);
        authBldr.createX509Filter(authenticationManager);
        authBldr.createLogoutFilter();
        authBldr.createLoginPageFilterIfNeeded();
        authBldr.createUserServiceInjector();
        authBldr.createExceptionTranslationFilter();

具体create分析下一篇再细说。接下来完成Filter的排序、并添加到filterChainMap集合中

List<OrderDecorator> unorderedFilterChain = new ArrayList<OrderDecorator>();

        unorderedFilterChain.addAll(httpBldr.getFilters());
        unorderedFilterChain.addAll(authBldr.getFilters());

        authenticationProviders.addAll(authBldr.getProviders());

        BeanDefinition requestCacheAwareFilter = new RootBeanDefinition(RequestCacheAwareFilter.class);
        requestCacheAwareFilter.getPropertyValues().addPropertyValue("requestCache", authBldr.getRequestCache());
        unorderedFilterChain.add(new OrderDecorator(requestCacheAwareFilter, REQUEST_CACHE_FILTER));

        unorderedFilterChain.addAll(buildCustomFilterList(element, pc));

        Collections.sort(unorderedFilterChain, new OrderComparator());
        checkFilterChainOrder(unorderedFilterChain, pc, source);

        List<BeanMetadataElement> filterChain = new ManagedList<BeanMetadataElement>();

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

        ManagedMap<BeanDefinition, List<BeanMetadataElement>> filterChainMap = httpBldr.getFilterChainMap();
        BeanDefinition universalMatch = new RootBeanDefinition(String.class);
        universalMatch.getConstructorArgumentValues().addGenericArgumentValue(matcher.getUniversalMatchPattern());
        filterChainMap.put(universalMatch, filterChain);

此时，已经为FilterChainProxy提供了必须的参数，接下来就是该完成FilterChainProxy的bean定义过程了

registerFilterChainProxy(pc, filterChainMap, matcher, source);

    private void registerFilterChainProxy(ParserContext pc, Map<BeanDefinition, List<BeanMetadataElement>> filterChainMap, UrlMatcher matcher, Object source) {
        if (pc.getRegistry().containsBeanDefinition(BeanIds.FILTER_CHAIN_PROXY)) {
            pc.getReaderContext().error("Duplicate <http> element detected", source);
        }
        //定义FilterChainProxy的BeanDefinition构造对象
         BeanDefinitionBuilder fcpBldr = BeanDefinitionBuilder.rootBeanDefinition(FilterChainProxy.class);
        fcpBldr.getRawBeanDefinition().setSource(source);
        fcpBldr.addPropertyValue("matcher", matcher);
        fcpBldr.addPropertyValue("stripQueryStringFromUrls", Boolean.valueOf(matcher instanceof AntUrlPathMatcher));
        //注入过滤器链
        fcpBldr.addPropertyValue("filterChainMap", filterChainMap);
        BeanDefinition fcpBean = fcpBldr.getBeanDefinition();
        //注册bean
        pc.registerBeanComponent(new BeanComponentDefinition(fcpBean, BeanIds.FILTER_CHAIN_PROXY));
        //注册bean的alias，其中别名为springSecurityFilterChain      
        pc.getRegistry().registerAlias(BeanIds.FILTER_CHAIN_PROXY, BeanIds.SPRING_SECURITY_FILTER_CHAIN);
    }

这里需要说明的是BeanDefinitionBuilder类，该类能够动态创建spring的bean，并通过ParserContext完成bean的注册，而不需要在xml中进行配置。
此时FilterChainProxy实例化过程已经完成。
二、invokeDelegate(delegateToUse, request, response, filterChain);
//调用代理类的doFilter方法

	protected void invokeDelegate(
			Filter delegate, ServletRequest request, ServletResponse response, FilterChain filterChain)
			throws ServletException, IOException {
		delegate.doFilter(request, response, filterChain);
	}

执行第一步获取的FilterChainProxy实例的doFilter方法。

通过以上分析，对FilterChainProxy如何产生的，以及Spring Security的标签是如何解析有了大体的认识。
具体标签的解析、Filter链的执行，下次再更新……

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