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……
评论
parsers.put(Elements.HTTP, new HttpSecurityBeanDefinitionParser())
有个疑问 请教下 。
这个 是不是说 只有当在spring容器中 能找到org.springframework.security.web.FilterChainProxy 实例时，才会将http的解析类放进来，
那么就会有个问题，遇到http解析的时候，这个地方的判断应该是false才对。所以不会放进来吧。
这个意思是说只有当前classloader能加载到org.springframework.security.web.FilterChainProxy这个类，才添加解析器，遇到http解析没关系的
parsers.put(Elements.HTTP, new HttpSecurityBeanDefinitionParser())
有个疑问 请教下 。
这个 是不是说 只有当在spring容器中 能找到org.springframework.security.web.FilterChainProxy 实例时，才会将http的解析类放进来，
那么就会有个问题，遇到http解析的时候，这个地方的判断应该是false才对。所以不会放进来吧。
上面的registerFilterChainProxy方法就是初始化springSecurityFilterChain并注册到spring中的
pc.getRegistry().registerAlias(BeanIds.FILTER_CHAIN_PROXY, BeanIds.SPRING_SECURITY_FILTER_CHAIN);
上面的registerFilterChainProxy方法就是初始化springSecurityFilterChain并注册到spring中的
pc.getRegistry().registerAlias(BeanIds.FILTER_CHAIN_PROXY, BeanIds.SPRING_SECURITY_FILTER_CHAIN);