这篇文章主要介绍了spring-boot是如何集成shiro的authentication流程的。

从shiro-spring-boot-web-starter说起

shiro-spring-boot-web-starter是shiro在web环境下快速集成至spring-boot的配置包。其本身引入了shiro的必要模块。并在Configuration中以@Bean的形式声明了Shiro各组件，交由spring容器统一管理。先看META-INF定义了配置类：

org.springframework.boot.autoconfigure.EnableAutoConfiguration = \  org.apache.shiro.spring.config.web.autoconfigure.ShiroWebAutoConfiguration,\  org.apache.shiro.spring.config.web.autoconfigure.ShiroWebFilterConfiguration

可以看到主要有两个配置：ShiroWebAutoConfiguration和ShiroWebFilterConfiguration。

• ShiroWebAutoConfiguration
  ShiroWebAutoConfiguration声明了Shiro需要的各个对象，在需要shiro框架进行处理的地方，可以方便注入，从而到达应用shiro特性的目的。同理，我们也可以根据需要替换上述部分Bean，让Shiro的流程更负责自己的业务需求。

/** * @since 1.4.0 */@Configuration@AutoConfigureBefore(ShiroAutoConfiguration.class)@ConditionalOnProperty(name = "shiro.web.enabled", matchIfMissing = true)public class ShiroWebAutoConfiguration extends AbstractShiroWebConfiguration {    //声明了认证时的策略，默认是AtLeastOneSuccessfulStrategy    @Bean    @ConditionalOnMissingBean    @Override    protected AuthenticationStrategy authenticationStrategy() {        return super.authenticationStrategy();    }    //声明Authenticator对象，负责认证的过程    @Bean    @ConditionalOnMissingBean    @Override    protected Authenticator authenticator() {        return super.authenticator();    }    //声明Authorizer的对象，负责授权的过程    @Bean    @ConditionalOnMissingBean    @Override    protected Authorizer authorizer() {        return super.authorizer();    }    //声明Subject数据访问对象，通过该对象可以对Subject数据进行CRUD操作    @Bean    @ConditionalOnMissingBean    @Override    protected SubjectDAO subjectDAO() {        return super.subjectDAO();    }    //声明SessionStorageEvaluator对象，用来决定Session是否需要持久化    @Bean    @ConditionalOnMissingBean    @Override    protected SessionStorageEvaluator sessionStorageEvaluator() {        return super.sessionStorageEvaluator();    }    //声明SubjectFactory，用来创建Subject对象    @Bean    @ConditionalOnMissingBean    @Override    protected SubjectFactory subjectFactory() {        return super.subjectFactory();    }    //声明SessionFactory对象，用来创建Session    @Bean    @ConditionalOnMissingBean    @Override    protected SessionFactory sessionFactory() {        return super.sessionFactory();    }    //声明Session数据访问对象，提供对Session的CRUD操作    @Bean    @ConditionalOnMissingBean    @Override    protected SessionDAO sessionDAO() {        return super.sessionDAO();    }    //声明SessionManager对象，负责Session管理    @Bean    @ConditionalOnMissingBean    @Override    protected SessionManager sessionManager() {        return super.sessionManager();    }    //声明SecurityMananger，Shiro中最重要的组件，对象内封装了各个其他对象，用来处理不同的业务    @Bean    @ConditionalOnMissingBean    @Override    protected SessionsSecurityManager securityManager(List
    
      realms) {        return createSecurityManager();    }    //创建会话cookie时的模板，后期应用该模板的属性到创建的cookie对象上    @Bean    @ConditionalOnMissingBean(name = "sessionCookieTemplate")    @Override    protected Cookie sessionCookieTemplate() {        return super.sessionCookieTemplate();    }    //Remember Me Manager，管理RememerMe    @Bean    @ConditionalOnMissingBean    @Override    protected RememberMeManager rememberMeManager() {        return super.rememberMeManager();    }    //RememberMe模板    @Bean    @ConditionalOnMissingBean(name = "rememberMeCookieTemplate")    @Override    protected Cookie rememberMeCookieTemplate() {        return super.rememberMeCookieTemplate();    }    //定义了Shiro的Filter和URL的映射关系    @Bean    @ConditionalOnMissingBean    @Override    protected ShiroFilterChainDefinition shiroFilterChainDefinition() {        return super.shiroFilterChainDefinition();    }}
    

• ShiroWebFilterConfiguration
  以往spring项目的权限控制大多也是通过过滤器或是拦截器实现的，即请求在到达控制器之前，先经过过滤器或拦截器的处理，如果校验成功，再将数据发送至控制器。Shiro也是利用同样的道理。

package org.apache.shiro.spring.config.web.autoconfigure;import javax.servlet.DispatcherType;import org.apache.shiro.spring.web.ShiroFilterFactoryBean;import org.apache.shiro.spring.web.config.AbstractShiroWebFilterConfiguration;import org.apache.shiro.web.servlet.AbstractShiroFilter;import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;import org.springframework.boot.web.servlet.FilterRegistrationBean;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;/** * @since 1.4.0 */@Configuration@ConditionalOnProperty(name = "shiro.web.enabled", matchIfMissing = true)public class ShiroWebFilterConfiguration extends AbstractShiroWebFilterConfiguration {    //ShiroFilter的FactoryBean，用来创建ShiroFilter    @Bean    @ConditionalOnMissingBean    @Override    protected ShiroFilterFactoryBean shiroFilterFactoryBean() {        return super.shiroFilterFactoryBean();    }    //ShiroFilter的RegistrationBean，spring-boot舍弃了web.xml的配置，FilterRegistrationBean就成了添加filter的入口    @Bean(name = "filterShiroFilterRegistrationBean")    @ConditionalOnMissingBean    protected FilterRegistrationBean filterShiroFilterRegistrationBean() throws Exception {        FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean();        filterRegistrationBean.setDispatcherTypes(DispatcherType.REQUEST, DispatcherType.FORWARD, DispatcherType.INCLUDE, DispatcherType.ERROR);        filterRegistrationBean.setFilter((AbstractShiroFilter) shiroFilterFactoryBean().getObject());        filterRegistrationBean.setOrder(1);        return filterRegistrationBean;    }}

FilterRegistrationBean主要设置了要添加的Filter

是由ShiroFilterFactoryBean所创建。因此，我们重点关注ShiroFilterFactoryBean。

ShiroFilterFactoryBean

ShiroFilterFactoryBean同时实现了FactoryBean和BeanPostProcessor。说明他同时有创建Bean和Bean的后置处理两种能力。简单看一下源代码：

package org.apache.shiro.spring.web;public class ShiroFilterFactoryBean implements FactoryBean, BeanPostProcessor {    private static transient final Logger log = LoggerFactory.getLogger(ShiroFilterFactoryBean.class);    private SecurityManager securityManager;    //定义了拦截器name和Filter的映射关系    private Map
    
      filters;    //定义了拦截器URL和name的映射关系    private Map
     
       filterChainDefinitionMap; //urlPathExpression_to_comma-delimited-filter-chain-definition    private String loginUrl;    private String successUrl;    private String unauthorizedUrl;    private AbstractShiroFilter instance;    public ShiroFilterFactoryBean() {        this.filters = new LinkedHashMap
      
       ();        this.filterChainDefinitionMap = new LinkedHashMap
       
        (); //order matters!    }        public SecurityManager getSecurityManager() {        return securityManager;    }        public void setSecurityManager(SecurityManager securityManager) {        this.securityManager = securityManager;    }        public String getLoginUrl() {        return loginUrl;    }        public void setLoginUrl(String loginUrl) {        this.loginUrl = loginUrl;    }        public String getSuccessUrl() {        return successUrl;    }        public void setSuccessUrl(String successUrl) {        this.successUrl = successUrl;    }        public String getUnauthorizedUrl() {        return unauthorizedUrl;    }        public void setUnauthorizedUrl(String unauthorizedUrl) {        this.unauthorizedUrl = unauthorizedUrl;    }        public Map
        
          getFilters() {        return filters;    }        public void setFilters(Map
         
           filters) { this.filters = filters; } public Map
          
            getFilterChainDefinitionMap() { return filterChainDefinitionMap; } public void setFilterChainDefinitionMap(Map
           
             filterChainDefinitionMap) { this.filterChainDefinitionMap = filterChainDefinitionMap; } //提供了通过ini配置文件初始化Filter的能力 public void setFilterChainDefinitions(String definitions) { Ini ini = new Ini(); ini.load(definitions); //did they explicitly state a 'urls' section? Not necessary, but just in case: Ini.Section section = ini.getSection(IniFilterChainResolverFactory.URLS); if (CollectionUtils.isEmpty(section)) { //no urls section. Since this _is_ a urls chain definition property, just assume the //default section contains only the definitions: section = ini.getSection(Ini.DEFAULT_SECTION_NAME); } setFilterChainDefinitionMap(section); } //FactoryBean获取Bean的方法，这里就是获取对应Filter Bean public Object getObject() throws Exception { if (instance == null) { instance = createInstance(); } return instance; } //FactoryBean获取生成的Bean的类型 public Class getObjectType() { return SpringShiroFilter.class; } //要生成的Bean是否需要是单例 public boolean isSingleton() { return true; } //创建FilterChainManager对象，该对象可以将对应的url和filter组成过滤器链 protected FilterChainManager createFilterChainManager() { DefaultFilterChainManager manager = new DefaultFilterChainManager(); //Shiro自带的Filter，不需要额外配置，可以开箱即用，详见DefualtFilter Map
            
              defaultFilters = manager.getFilters(); for (Filter filter : defaultFilters.values()) { applyGlobalPropertiesIfNecessary(filter); } //获取ShiroFactoryBean中自定义的Filters，添加至manager中 Map
             
               filters = getFilters(); if (!CollectionUtils.isEmpty(filters)) { for (Map.Entry
              
                entry : filters.entrySet()) { String name = entry.getKey(); Filter filter = entry.getValue(); applyGlobalPropertiesIfNecessary(filter); if (filter instanceof Nameable) { ((Nameable) filter).setName(name); } //'init' argument is false, since Spring-configured filters should be initialized //in Spring (i.e. 'init-method=blah') or implement InitializingBean: manager.addFilter(name, filter, false); } } //根据定义的url和filter映射关系，创建过滤器链 Map
               
                 chains = getFilterChainDefinitionMap(); if (!CollectionUtils.isEmpty(chains)) { for (Map.Entry
                
                  entry : chains.entrySet()) { String url = entry.getKey(); String chainDefinition = entry.getValue(); manager.createChain(url, chainDefinition); } } return manager; } //创建ShiroFilter的实例 protected AbstractShiroFilter createInstance() throws Exception { log.debug("Creating Shiro Filter instance."); SecurityManager securityManager = getSecurityManager(); if (securityManager == null) { String msg = "SecurityManager property must be set."; throw new BeanInitializationException(msg); } if (!(securityManager instanceof WebSecurityManager)) { String msg = "The security manager does not implement the WebSecurityManager interface."; throw new BeanInitializationException(msg); } FilterChainManager manager = createFilterChainManager(); //Expose the constructed FilterChainManager by first wrapping it in a // FilterChainResolver implementation. The AbstractShiroFilter implementations // do not know about FilterChainManagers - only resolvers: //创建FilterChainResolver对象，FilterChainResolver包装了Manager，ShiroFilter不需要知道Manager对象 PathMatchingFilterChainResolver chainResolver = new PathMatchingFilterChainResolver(); chainResolver.setFilterChainManager(manager); //Now create a concrete ShiroFilter instance and apply the acquired SecurityManager and built //FilterChainResolver. It doesn't matter that the instance is an anonymous inner class //here - we're just using it because it is a concrete AbstractShiroFilter instance that accepts //injection of the SecurityManager and FilterChainResolver: //创建ShiroFilter对象 return new SpringShiroFilter((WebSecurityManager) securityManager, chainResolver); } private void applyLoginUrlIfNecessary(Filter filter) { String loginUrl = getLoginUrl(); if (StringUtils.hasText(loginUrl) && (filter instanceof AccessControlFilter)) { AccessControlFilter acFilter = (AccessControlFilter) filter; //only apply the login url if they haven't explicitly configured one already: String existingLoginUrl = acFilter.getLoginUrl(); if (AccessControlFilter.DEFAULT_LOGIN_URL.equals(existingLoginUrl)) { acFilter.setLoginUrl(loginUrl); } } } private void applySuccessUrlIfNecessary(Filter filter) { String successUrl = getSuccessUrl(); if (StringUtils.hasText(successUrl) && (filter instanceof AuthenticationFilter)) { AuthenticationFilter authcFilter = (AuthenticationFilter) filter; //only apply the successUrl if they haven't explicitly configured one already: String existingSuccessUrl = authcFilter.getSuccessUrl(); if (AuthenticationFilter.DEFAULT_SUCCESS_URL.equals(existingSuccessUrl)) { authcFilter.setSuccessUrl(successUrl); } } } private void applyUnauthorizedUrlIfNecessary(Filter filter) { String unauthorizedUrl = getUnauthorizedUrl(); if (StringUtils.hasText(unauthorizedUrl) && (filter instanceof AuthorizationFilter)) { AuthorizationFilter authzFilter = (AuthorizationFilter) filter; //only apply the unauthorizedUrl if they haven't explicitly configured one already: String existingUnauthorizedUrl = authzFilter.getUnauthorizedUrl(); if (existingUnauthorizedUrl == null) { authzFilter.setUnauthorizedUrl(unauthorizedUrl); } } } //配置全局属性，只要是针对特定类型的Filter配置其所需要的URL属性 private void applyGlobalPropertiesIfNecessary(Filter filter) { applyLoginUrlIfNecessary(filter); applySuccessUrlIfNecessary(filter); applyUnauthorizedUrlIfNecessary(filter); } //通过后置处理器的机制，直接Filter类型的bean，无需配置 public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException { if (bean instanceof Filter) { log.debug("Found filter chain candidate filter '{}'", beanName); Filter filter = (Filter) bean; applyGlobalPropertiesIfNecessary(filter); getFilters().put(beanName, filter); } else { log.trace("Ignoring non-Filter bean '{}'", beanName); } return bean; } /** * Does nothing - only exists to satisfy the BeanPostProcessor interface and immediately returns the * {@code bean} argument. */ public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException { return bean; } //SpringShiroFilter只是简单的集成了AbstractShirlFilter，在构造函数中封装了设置SecurityManager和Resolver的操作 private static final class SpringShiroFilter extends AbstractShiroFilter { protected SpringShiroFilter(WebSecurityManager webSecurityManager, FilterChainResolver resolver) { super(); if (webSecurityManager == null) { throw new IllegalArgumentException("WebSecurityManager property cannot be null."); } setSecurityManager(webSecurityManager); if (resolver != null) { setFilterChainResolver(resolver); } } }}
                
               
              
             
            
           
          
         
        
       
      
     
    

最重要的步骤是在createInstance()中，该方法主要用来创建ShiroFilter的实例，大致过程分成三步：

1. 通过createFilterChainManager()创建FilterChainManager对象：
   • 创建FilterChainManager
   • 加载Shiro默认的Filter
   • 加载用户添加的Filter
   • 根据URL和Filter的映射关系，创建过滤器链
2. 创建FilterChainResolver对象，封装FilterChainManager
3. 创建ShiroFilter对象，传入SecurityManager和FilterChainReslover

SpringShiroFilter

SpringShiroFilter就是我们通过容器添加的Filter对象。Shiro通过添加该过滤器实现了往集成Spring框架集成的目的。

其实SpringShiroFilter只是单纯的集成了AbstractShiroFilter，在构造函数中增加了设置SecurityManager和FilterChainResolver的过程。所有的逻辑在AbstractShiroFilter中已经定义好了。先从UML图中了解下整个类的继承关系：

其中从上到下看：

• Filter
  Filter是Serlvet包提供的。由Servlet规范定义Filter基本的行为。
• ServletContextSupport
  提供了操作ServletContext的能力
• AbstractFilter
  初步实现了Filter，定义了init的过程（分成setFilterConfig和onFilterConfigSet两部分），提供了设置和获取配置的方法。
• Nameable
  增加了命名的能力
• NameableFilter
  为Filter增加命名能力
• OncePerRequestFilter
  主要定义了doFilter的过程，并在该过程中限制了一次请求该Filter只处理一次。

public final void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain)            throws ServletException, IOException {            //先判断是否已经被处理过        String alreadyFilteredAttributeName = getAlreadyFilteredAttributeName();        if ( //已经处理过，则不再处理 request.getAttribute(alreadyFilteredAttributeName) != null ) {            log.trace("Filter '{}' already executed.  Proceeding without invoking this filter.", getName());            filterChain.doFilter(request, response);        } else //noinspection deprecation        //未处理过，但是不可用，也不处理            if (/* added in 1.2: */ !isEnabled(request, response) ||                /* retain backwards compatibility: */ shouldNotFilter(request) ) {            log.debug("Filter '{}' is not enabled for the current request.  Proceeding without invoking this filter.",                    getName());            filterChain.doFilter(request, response);        } else {        //调用Filter处理，并添加已处理属性            // Do invoke this filter...            log.trace("Filter '{}' not yet executed.  Executing now.", getName());            request.setAttribute(alreadyFilteredAttributeName, Boolean.TRUE);            try {            //抽象方法，交给子类实现                doFilterInternal(request, response, filterChain);            } finally {                // Once the request has finished, we're done and we don't                // need to mark as 'already filtered' any more.                request.removeAttribute(alreadyFilteredAttributeName);            }        }    }

• AbstractShiroFilter
  AbstractShiroFilter已经在Filter的处理过程中添加了Shiro的验证。

package org.apache.shiro.web.servlet;import org.apache.shiro.SecurityUtils;import org.apache.shiro.session.Session;import org.apache.shiro.subject.ExecutionException;import org.apache.shiro.subject.Subject;import org.apache.shiro.web.filter.mgt.FilterChainResolver;import org.apache.shiro.web.mgt.DefaultWebSecurityManager;import org.apache.shiro.web.mgt.WebSecurityManager;import org.apache.shiro.web.subject.WebSubject;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import javax.servlet.FilterChain;import javax.servlet.ServletException;import javax.servlet.ServletRequest;import javax.servlet.ServletResponse;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import java.io.IOException;import java.util.concurrent.Callable;public abstract class AbstractShiroFilter extends OncePerRequestFilter {    private static final Logger log = LoggerFactory.getLogger(AbstractShiroFilter.class);    private static final String STATIC_INIT_PARAM_NAME = "staticSecurityManagerEnabled";    // Reference to the security manager used by this filter    private WebSecurityManager securityManager;    // Used to determine which chain should handle an incoming request/response    private FilterChainResolver filterChainResolver;    /**     * Whether or not to bind the constructed SecurityManager instance to static memory (via     * SecurityUtils.setSecurityManager).  This was added to support https://issues.apache.org/jira/browse/SHIRO-287     * @since 1.2     */    private boolean staticSecurityManagerEnabled;    protected AbstractShiroFilter() {        this.staticSecurityManagerEnabled = false;    }    public WebSecurityManager getSecurityManager() {        return securityManager;    }    public void setSecurityManager(WebSecurityManager sm) {        this.securityManager = sm;    }    public FilterChainResolver getFilterChainResolver() {        return filterChainResolver;    }    public void setFilterChainResolver(FilterChainResolver filterChainResolver) {        this.filterChainResolver = filterChainResolver;    }    public boolean isStaticSecurityManagerEnabled() {        return staticSecurityManagerEnabled;    }    public void setStaticSecurityManagerEnabled(boolean staticSecurityManagerEnabled) {        this.staticSecurityManagerEnabled = staticSecurityManagerEnabled;    }    //重写了AbstractFilter中的空实现，主要设置额外的配置    protected final void onFilterConfigSet() throws Exception {        //added in 1.2 for SHIRO-287:        applyStaticSecurityManagerEnabledConfig();        init();        ensureSecurityManager();        //added in 1.2 for SHIRO-287:        if (isStaticSecurityManagerEnabled()) {            SecurityUtils.setSecurityManager(getSecurityManager());        }    }        private void applyStaticSecurityManagerEnabledConfig() {        String value = getInitParam(STATIC_INIT_PARAM_NAME);        if (value != null) {            Boolean b = Boolean.valueOf(value);            if (b != null) {                setStaticSecurityManagerEnabled(b);            }        }    }    public void init() throws Exception {    }        private void ensureSecurityManager() {        WebSecurityManager securityManager = getSecurityManager();        if (securityManager == null) {            log.info("No SecurityManager configured.  Creating default.");            securityManager = createDefaultSecurityManager();            setSecurityManager(securityManager);        }    }    protected WebSecurityManager createDefaultSecurityManager() {        return new DefaultWebSecurityManager();    }    protected boolean isHttpSessions() {        return getSecurityManager().isHttpSessionMode();    }        protected ServletRequest wrapServletRequest(HttpServletRequest orig) {        return new ShiroHttpServletRequest(orig, getServletContext(), isHttpSessions());    }        @SuppressWarnings({"UnusedDeclaration"})    protected ServletRequest prepareServletRequest(ServletRequest request, ServletResponse response, FilterChain chain) {        ServletRequest toUse = request;        if (request instanceof HttpServletRequest) {            HttpServletRequest http = (HttpServletRequest) request;            toUse = wrapServletRequest(http);        }        return toUse;    }        protected ServletResponse wrapServletResponse(HttpServletResponse orig, ShiroHttpServletRequest request) {        return new ShiroHttpServletResponse(orig, getServletContext(), request);    }        @SuppressWarnings({"UnusedDeclaration"})    protected ServletResponse prepareServletResponse(ServletRequest request, ServletResponse response, FilterChain chain) {        ServletResponse toUse = response;        if (!isHttpSessions() && (request instanceof ShiroHttpServletRequest) &&                (response instanceof HttpServletResponse)) {            //the ShiroHttpServletResponse exists to support URL rewriting for session ids.  This is only needed if            //using Shiro sessions (i.e. not simple HttpSession based sessions):            toUse = wrapServletResponse((HttpServletResponse) response, (ShiroHttpServletRequest) request);        }        return toUse;    }        protected WebSubject createSubject(ServletRequest request, ServletResponse response) {        return new WebSubject.Builder(getSecurityManager(), request, response).buildWebSubject();    }    //对Session生命周期未交给Web容器管理的情况，由Shiro自己维护    @SuppressWarnings({"UnusedDeclaration"})    protected void updateSessionLastAccessTime(ServletRequest request, ServletResponse response) {        if (!isHttpSessions()) { //'native' sessions            Subject subject = SecurityUtils.getSubject();            //Subject should never _ever_ be null, but just in case:            if (subject != null) {                Session session = subject.getSession(false);                if (session != null) {                    try {                        session.touch();                    } catch (Throwable t) {                        log.error("session.touch() method invocation has failed.  Unable to update" +                                "the corresponding session's last access time based on the incoming request.", t);                    }                }            }        }    }    //重写OncePerRequestFilter的空实现，定义了Filter处理逻辑    protected void doFilterInternal(ServletRequest servletRequest, ServletResponse servletResponse, final FilterChain chain)            throws ServletException, IOException {        Throwable t = null;        try {            //封装ServletRequest和ServletResponse            final ServletRequest request = prepareServletRequest(servletRequest, servletResponse, chain);            final ServletResponse response = prepareServletResponse(request, servletResponse, chain);            //创建Subject对象                final Subject subject = createSubject(request, response);            //noinspection unchecked            subject.execute(new Callable() {                public Object call() throws Exception {                    //更新Session访问时间                    updateSessionLastAccessTime(request, response);                    //执行任务链                    executeChain(request, response, chain);                    return null;                }            });        } catch (ExecutionException ex) {            t = ex.getCause();        } catch (Throwable throwable) {            t = throwable;        }        if (t != null) {            if (t instanceof ServletException) {                throw (ServletException) t;            }            if (t instanceof IOException) {                throw (IOException) t;            }            //otherwise it's not one of the two exceptions expected by the filter method signature - wrap it in one:            String msg = "Filtered request failed.";            throw new ServletException(msg, t);        }    }    //获取待执行的过滤器链    protected FilterChain getExecutionChain(ServletRequest request, ServletResponse response, FilterChain origChain) {        FilterChain chain = origChain;        //获取过滤器链解析器        FilterChainResolver resolver = getFilterChainResolver();        if (resolver == null) {            log.debug("No FilterChainResolver configured.  Returning original FilterChain.");            return origChain;        }        //使用解析器对请求进行解析，        FilterChain resolved = resolver.getChain(request, response, origChain);        if (resolved != null) {            //如果该请求URI是需要Shiro拦截的，则由shiro创建代理的过滤器链，            //在执行原始的过滤器前，插入Shiro过滤器的执行过程            log.trace("Resolved a configured FilterChain for the current request.");            chain = resolved;        } else {//否则使用原始过滤器            log.trace("No FilterChain configured for the current request.  Using the default.");        }        return chain;    }    //执行拦截器链    protected void executeChain(ServletRequest request, ServletResponse response, FilterChain origChain)            throws IOException, ServletException {        //获取拦截器链                FilterChain chain = getExecutionChain(request, response, origChain);        //拦截器链处理拦截工作        chain.doFilter(request, response);    }}

其中比较重要的有两个：onFilterConfigSet()和doFilterInternal()。

onFilterConfigset()在AbstractFilter中是空实现，这里重写了该方法，主要是添加一些额外配置。

doFilterInternal()主要流程：

• 先封装了请求和响应
• 获取请求代表的Subject对象
• 更新session最后访问的时间（托管给WEB容器的session不需要shiro管理访问时间）
• 执行拦截器链executeChain:
  • 获取拦截器链： 如果FilterChainResolver解析到请求的URL是shiro拦截器拦截的URL，则产生代理的FilterChain，让shiro的拦截器集成进拦截器；否则使用原始的拦截器链
  • 拦截器链开始工作

FilterChainResolver和FilterChainManager的工作

之前简单介绍过FilterChainResolver封装了FilterChainManger对象，现在再来看下FilterChainResovler的代码：

public class PathMatchingFilterChainResolver implements FilterChainResolver {    private static transient final Logger log = LoggerFactory.getLogger(PathMatchingFilterChainResolver.class);    //封装了FilterChainManager    private FilterChainManager filterChainManager;    //负责比较URL    private PatternMatcher pathMatcher;    public PathMatchingFilterChainResolver() {        this.pathMatcher = new AntPathMatcher();        this.filterChainManager = new DefaultFilterChainManager();    }    public PathMatchingFilterChainResolver(FilterConfig filterConfig) {        this.pathMatcher = new AntPathMatcher();        this.filterChainManager = new DefaultFilterChainManager(filterConfig);    }        public PatternMatcher getPathMatcher() {        return pathMatcher;    }        public void setPathMatcher(PatternMatcher pathMatcher) {        this.pathMatcher = pathMatcher;    }    public FilterChainManager getFilterChainManager() {        return filterChainManager;    }    @SuppressWarnings({"UnusedDeclaration"})    public void setFilterChainManager(FilterChainManager filterChainManager) {        this.filterChainManager = filterChainManager;    }    //获取拦截器链    public FilterChain getChain(ServletRequest request, ServletResponse response, FilterChain originalChain) {        FilterChainManager filterChainManager = getFilterChainManager();        if (!filterChainManager.hasChains()) {            return null;        }        //获取URL        String requestURI = getPathWithinApplication(request);        //匹配URL        for (String pathPattern : filterChainManager.getChainNames()) {            //如果匹配，则由filterChainManager创建代理过的Filter Chain            if (pathMatches(pathPattern, requestURI)) {                if (log.isTraceEnabled()) {                    log.trace("Matched path pattern [" + pathPattern + "] for requestURI [" + requestURI + "].  " +                            "Utilizing corresponding filter chain...");                }                return filterChainManager.proxy(originalChain, pathPattern);            }        }        return null;    }        protected boolean pathMatches(String pattern, String path) {        PatternMatcher pathMatcher = getPathMatcher();        return pathMatcher.matches(pattern, path);    }        protected String getPathWithinApplication(ServletRequest request) {        return WebUtils.getPathWithinApplication(WebUtils.toHttp(request));    }}

这个类的代码相对简单，大概过程是根据FilterChainManager配置的URI和Filter的映射关系，比较请求是否需要经过Shiro的Filter，如果需要则交给了FilterChainManager对象创建代理过的FilterChain，从而加入了Shiro的处理流程。可以看到主要的内容都是由FilterChainManager完成。因此我们再来看FilterChainManager类的proxy方法：

public FilterChain proxy(FilterChain original, String chainName) {        //NamedFilterList对象可以简单理解为一个命名了Filter的list，是之前解析filter时，创建的        NamedFilterList configured = getChain(chainName);        if (configured == null) {            String msg = "There is no configured chain under the name/key [" + chainName + "].";            throw new IllegalArgumentException(msg);        }        //创建代理        return configured.proxy(original);    }

NamedFilterList创建代理的过程其实就是创建ProxiedFilterChain对象。

public class ProxiedFilterChain implements FilterChain {    //TODO - complete JavaDoc    private static final Logger log = LoggerFactory.getLogger(ProxiedFilterChain.class);    private FilterChain orig;    private List
    
      filters;    private int index = 0;    public ProxiedFilterChain(FilterChain orig, List
     
       filters) {        if (orig == null) {            throw new NullPointerException("original FilterChain cannot be null.");        }        //封装了原始filterChain对象和shiro的filter对象        this.orig = orig;        this.filters = filters;        this.index = 0;    }    //实现了filterChain的doFilter方法    public void doFilter(ServletRequest request, ServletResponse response) throws IOException, ServletException {        //如果不含有shiro的filter，或是已经遍历完了shiro的filter，则调用原始的fiter chain的方法        if (this.filters == null || this.filters.size() == this.index) {            //we've reached the end of the wrapped chain, so invoke the original one:            if (log.isTraceEnabled()) {                log.trace("Invoking original filter chain.");            }            this.orig.doFilter(request, response);        } else {            if (log.isTraceEnabled()) {                log.trace("Invoking wrapped filter at index [" + this.index + "]");            }            //调用shiro的filter            this.filters.get(this.index++).doFilter(request, response, this);        }    }}
     
    

源码读到这里已经大致了解到shiro是如何集成至spring-boot的。接下来再以一个Shiro的Filter为例，具体了解下authentication的流程。

从FormAuthenticatingFilter了解Shiro的authentication过程

一样先看Filter的继承结构：

OncePerRequestFilter父级的结构已经在前文介绍过。现在关注点放在它的子类上。

• AdviceFilter：
  主要实现了doFilterInternal方法，将filter的过程再切成preHandle，executeChain，postHandle和cleanup四个阶段。有点类似spring中的拦截器。在方法前，方法后做了拦截。并根据返回的结果决定是否继续再filterChain中往下走：

public void doFilterInternal(ServletRequest request, ServletResponse response, FilterChain chain)            throws ServletException, IOException {        Exception exception = null;        try {            //前置处理，根据返回结构决定是否继续走之后的filter            boolean continueChain = preHandle(request, response);            if (log.isTraceEnabled()) {                log.trace("Invoked preHandle method.  Continuing chain?: [" + continueChain + "]");            }                        //继续调用之后的filter            if (continueChain) {                executeChain(request, response, chain);            }                        //后置处理            postHandle(request, response);            if (log.isTraceEnabled()) {                log.trace("Successfully invoked postHandle method");            }        } catch (Exception e) {            exception = e;        } finally {        //清理            cleanup(request, response, exception);        }    }

• PathMatchingFilter：根据url是否匹配的逻辑实现preHandle方法。并提供onPreHandle方法让子类可以修改preHandle方法返回的值。

protected boolean preHandle(ServletRequest request, ServletResponse response) throws Exception {        if (this.appliedPaths == null || this.appliedPaths.isEmpty()) {            if (log.isTraceEnabled()) {                log.trace("appliedPaths property is null or empty.  This Filter will passthrough immediately.");            }            return true;        }        //匹配请求URL，决定是否需要经过shiro的filter        for (String path : this.appliedPaths.keySet()) {                        if (pathsMatch(path, request)) {                log.trace("Current requestURI matches pattern '{}'.  Determining filter chain execution...", path);                Object config = this.appliedPaths.get(path);                return isFilterChainContinued(request, response, path, config);            }        }        //no path matched, allow the request to go through:        return true;    }        @SuppressWarnings({"JavaDoc"})    private boolean isFilterChainContinued(ServletRequest request, ServletResponse response,                                           String path, Object pathConfig) throws Exception {        if (isEnabled(request, response, path, pathConfig)) { //isEnabled check added in 1.2            if (log.isTraceEnabled()) {                log.trace("Filter '{}' is enabled for the current request under path '{}' with config [{}].  " +                        "Delegating to subclass implementation for 'onPreHandle' check.",                        new Object[]{getName(), path, pathConfig});            }            //添加onPreHandle方法            return onPreHandle(request, response, pathConfig);        }        if (log.isTraceEnabled()) {            log.trace("Filter '{}' is disabled for the current request under path '{}' with config [{}].  " +                    "The next element in the FilterChain will be called immediately.",                    new Object[]{getName(), path, pathConfig});        }        //This filter is disabled for this specific request,        //return 'true' immediately to indicate that the filter will not process the request        //and let the request/response to continue through the filter chain:        return true;    }    //默认返回true，子类可以重写该方法实现自己的控制逻辑    protected boolean onPreHandle(ServletRequest request, ServletResponse response, Object mappedValue) throws Exception {        return true;    }

• AccessControlFilter:主要重写了onPreHandle方法，增加了isAccessAllowed和onAccessDenied方法。可以在该方法中实现访问控制的逻辑。

public boolean onPreHandle(ServletRequest request, ServletResponse response, Object mappedValue) throws Exception {        return isAccessAllowed(request, response, mappedValue) || onAccessDenied(request, response, mappedValue);    }

• AuthenticationFilter:实现了isAccessAllowed方法，通过subject.isAuthenticated()决定是否允许访问。

protected boolean isAccessAllowed(ServletRequest request, ServletResponse response, Object mappedValue) {        Subject subject = getSubject(request, response);        return subject.isAuthenticated();    }

• AuthenticatingFilter：除了主要的isAccessAllowed和cleanup方法之外，还实现了executeLogin方法，主要是从请求中获取登录的用户名密码，通过shiro进行登录验证
• FormAuthenticationFilter:最后具体看一下FormAuthenticationFilter。

public class FormAuthenticationFilter extends AuthenticatingFilter {    //TODO - complete JavaDoc    public static final String DEFAULT_ERROR_KEY_ATTRIBUTE_NAME = "shiroLoginFailure";    public static final String DEFAULT_USERNAME_PARAM = "username";    public static final String DEFAULT_PASSWORD_PARAM = "password";    public static final String DEFAULT_REMEMBER_ME_PARAM = "rememberMe";    private static final Logger log = LoggerFactory.getLogger(FormAuthenticationFilter.class);    private String usernameParam = DEFAULT_USERNAME_PARAM;    private String passwordParam = DEFAULT_PASSWORD_PARAM;    private String rememberMeParam = DEFAULT_REMEMBER_ME_PARAM;    private String failureKeyAttribute = DEFAULT_ERROR_KEY_ATTRIBUTE_NAME;    public FormAuthenticationFilter() {        setLoginUrl(DEFAULT_LOGIN_URL);    }    @Override    public void setLoginUrl(String loginUrl) {        String previous = getLoginUrl();        if (previous != null) {            this.appliedPaths.remove(previous);        }        super.setLoginUrl(loginUrl);        if (log.isTraceEnabled()) {            log.trace("Adding login url to applied paths.");        }        this.appliedPaths.put(getLoginUrl(), null);    }    public String getUsernameParam() {        return usernameParam;    }    public void setUsernameParam(String usernameParam) {        this.usernameParam = usernameParam;    }    public String getPasswordParam() {        return passwordParam;    }    public void setPasswordParam(String passwordParam) {        this.passwordParam = passwordParam;    }    public String getRememberMeParam() {        return rememberMeParam;    }    public void setRememberMeParam(String rememberMeParam) {        this.rememberMeParam = rememberMeParam;    }    public String getFailureKeyAttribute() {        return failureKeyAttribute;    }    public void setFailureKeyAttribute(String failureKeyAttribute) {        this.failureKeyAttribute = failureKeyAttribute;    }    //    protected boolean onAccessDenied(ServletRequest request, ServletResponse response) throws Exception {        //如果isAccessAllowed校验失败，则判断是否是登录请求        if (isLoginRequest(request, response)) {            //如果是表单提交的登录请求，则执行登录，            if (isLoginSubmission(request, response)) {                if (log.isTraceEnabled()) {                    log.trace("Login submission detected.  Attempting to execute login.");                }                //登录                return executeLogin(request, response);            } else {                if (log.isTraceEnabled()) {                    log.trace("Login page view.");                }                //allow them to see the login page ;)                return true;            }        } else {            if (log.isTraceEnabled()) {                log.trace("Attempting to access a path which requires authentication.  Forwarding to the " +                        "Authentication url [" + getLoginUrl() + "]");            }            saveRequestAndRedirectToLogin(request, response);            return false;        }    }    @SuppressWarnings({"UnusedDeclaration"})    protected boolean isLoginSubmission(ServletRequest request, ServletResponse response) {        return (request instanceof HttpServletRequest) && WebUtils.toHttp(request).getMethod().equalsIgnoreCase(POST_METHOD);    }    protected AuthenticationToken createToken(ServletRequest request, ServletResponse response) {        String username = getUsername(request);        String password = getPassword(request);        return createToken(username, password, request, response);    }    protected boolean isRememberMe(ServletRequest request) {        return WebUtils.isTrue(request, getRememberMeParam());    }    //定义了一些重定向动作    protected boolean onLoginSuccess(AuthenticationToken token, Subject subject,                                     ServletRequest request, ServletResponse response) throws Exception {        issueSuccessRedirect(request, response);        //we handled the success redirect directly, prevent the chain from continuing:        return false;    }    protected boolean onLoginFailure(AuthenticationToken token, AuthenticationException e,                                     ServletRequest request, ServletResponse response) {        if (log.isDebugEnabled()) {            log.debug( "Authentication exception", e );        }        setFailureAttribute(request, e);        //login failed, let request continue back to the login page:        return true;    }    protected void setFailureAttribute(ServletRequest request, AuthenticationException ae) {        String className = ae.getClass().getName();        request.setAttribute(getFailureKeyAttribute(), className);    }    protected String getUsername(ServletRequest request) {        return WebUtils.getCleanParam(request, getUsernameParam());    }    protected String getPassword(ServletRequest request) {        return WebUtils.getCleanParam(request, getPasswordParam());    }}

总结

shiro通过FilterRegistrationBean添加了ShiroFilter。ShiroFilter在针对需要登录验证的请求，将原始的fiterChain进行代理，从而集成了shiro权限验证的filter。