springSecurity安全框架的学习和原理解读

最近在公司的项目中使用了spring security框架，所以有机会来学习一下，公司的项目是使用springboot搭建 springBoot版本1.59

spring security 版本4.2.3

（个人理解可能会有偏差，希望有不正确之处，大家能够指出来，共同探讨交流。）

一、Spring security框架简介

2、WebSecurityConfiguration类

3、AbstractSecurityBuilder类

4、举例说明如何将一个Configurer转换为filter

三、用户登录的验证和授权过程

一、Spring security框架简介

1、简介

一个能够为基于Spring的企业应用系统提供声明式的安全訪问控制解决方式的安全框架（简单说是对访问权限进行控制嘛），应用的安全性包括用户认证（Authentication）和用户授权（Authorization）两个部分。用户认证指的是验证某个用户是否为系统中的合法主体，也就是说用户能否访问该系统。用户认证一般要求用户提供用户名和密码。系统通过校验用户名和密码来完成认证过程。用户授权指的是验证某个用户是否有权限执行某个操作。在一个系统中，不同用户所具有的权限是不同的。比如对一个文件来说，有的用户只能进行读取，而有的用户可以进行修改。一般来说，系统会为不同的用户分配不同的角色，而每个角色则对应一系列的权限。 spring security的主要核心功能为认证和授权，所有的架构也是基于这两个核心功能去实现的。

2、框架原理

众所周知想要对对Web资源进行保护，最好的办法莫过于Filter，要想对方法调用进行保护，最好的办法莫过于AOP。所以springSecurity在我们进行用户认证以及授予权限的时候，通过各种各样的拦截器来控制权限的访问，从而实现安全。

如下为其主要过滤器

WebAsyncManagerIntegrationFilter
SecurityContextPersistenceFilter
HeaderWriterFilter
CorsFilter
LogoutFilter
RequestCacheAwareFilter
SecurityContextHolderAwareRequestFilter
AnonymousAuthenticationFilter
SessionManagementFilter
ExceptionTranslationFilter
FilterSecurityInterceptor
UsernamePasswordAuthenticationFilter
BasicAuthenticationFilter

3、框架的核心组件

SecurityContextHolder：提供对SecurityContext的访问
SecurityContext,：持有Authentication对象和其他可能需要的信息
AuthenticationManager 其中可以包含多个AuthenticationProvider
ProviderManager对象为AuthenticationManager接口的实现类
AuthenticationProvider 主要用来进行认证操作的类调用其中的authenticate()方法去进行认证操作
Authentication：Spring Security方式的认证主体
GrantedAuthority：对认证主题的应用层面的授权，含当前用户的权限信息，通常使用角色表示
UserDetails：构建Authentication对象必须的信息，可以自定义，可能需要访问DB得到
UserDetailsService：通过username构建UserDetails对象，通过loadUserByUsername根据userName获取UserDetail对象（可以在这里基于自身业务进行自定义的实现如通过数据库，xml,缓存获取等）

二、自定义安全配置的加载机制

1、前提基于自身业务需要

有关springSecrity安全框架的理解参考：springSecurity安全框架介绍

自定义了一个springSecurity安全框架的配置类继承WebSecurityConfigurerAdapter，重写其中的方法configure，但是并不清楚自定义的类是如何被加载并起到作用，这里一步步通过debug来了解其中的加载原理。

其实在我们实现该类后，在web容器启动的过程中该类实例对象会被WebSecurityConfiguration类处理。

@Configuration

public class SpringSecurityConfig extends WebSecurityConfigurerAdapter {

    @Autowired

    private AccessDeniedHandler accessDeniedHandler;

    @Autowired

    private CustAuthenticationProvider custAuthenticationProvider;

    // roles admin allow to access /admin/**

    // roles user allow to access /user/**

    // custom 403 access denied handler

    //重写了其中的configure（）方法设置了不同url的不同访问权限

    @Override

    protected void configure(HttpSecurity http) throws Exception {

        http.csrf().disable()

                .authorizeRequests()

                .antMatchers("/home", "/about","/img/*").permitAll()

                .antMatchers("/admin/**","/upload/**").hasAnyRole("ADMIN")

                .antMatchers("/order/**").hasAnyRole("USER","ADMIN")

                .antMatchers("/room/**").hasAnyRole("USER","ADMIN")

                .anyRequest().authenticated()

                .and()

                .formLogin()

                .loginPage("/login")

                .permitAll()

                .and()

                .logout()

                .permitAll()

                .and()

                .exceptionHandling().accessDeniedHandler(accessDeniedHandler);

    }

    // create two users, admin and user

    @Autowired

    public void configureGlobal(AuthenticationManagerBuilder auth) throws Exception {

//        auth.inMemoryAuthentication()

//                .withUser("user").password("user").roles("USER")

//                .and()

//                .withUser("admin").password("admin").roles("ADMIN");

//        auth.jdbcAuthentication()

        auth.authenticationProvider(custAuthenticationProvider);

    }

2、WebSecurityConfiguration类

@Configuration

public class WebSecurityConfiguration implements ImportAware, BeanClassLoaderAware {

    private WebSecurity webSecurity;

    private Boolean debugEnabled;

    private List<SecurityConfigurer<Filter, WebSecurity>> webSecurityConfigurers;

    private ClassLoader beanClassLoader;

   ...省略部分代码

    @Bean(

        name = {"springSecurityFilterChain"}

    )

    public Filter springSecurityFilterChain() throws Exception {

        boolean hasConfigurers = this.webSecurityConfigurers != null

         && !this.webSecurityConfigurers.isEmpty();

        if(!hasConfigurers) {

            WebSecurityConfigurerAdapter adapter = (WebSecurityConfigurerAdapter)

            this.objectObjectPostProcessor

              .postProcess(new WebSecurityConfigurerAdapter() {

            });

            this.webSecurity.apply(adapter);

        }

        return (Filter)this.webSecurity.build();

    }

    /*1、先执行该方法将我们自定义springSecurity配置实例

       （可能还有系统默认的有关安全的配置实例 ） 配置实例中含有我们自定义业务的权限控制配置信息

       放入到该对象的list数组中webSecurityConfigurers中

       使用@Value注解来将实例对象作为形参注入

     */

 @Autowired(

        required = false

    )

    public void setFilterChainProxySecurityConfigurer(ObjectPostProcessor<Object>

    objectPostProcessor,

   @Value("#{@autowiredWebSecurityConfigurersIgnoreParents.getWebSecurityConfigurers()}")

  List<SecurityConfigurer<Filter, WebSecurity>> webSecurityConfigurers)

throws Exception {

    //创建一个webSecurity对象

    this.webSecurity = (WebSecurity)objectPostProcessor.postProcess(new WebSecurity(objectPostProcessor));

        if(this.debugEnabled != null) {

            this.webSecurity.debug(this.debugEnabled.booleanValue());

        }

        //对所有配置类的实例进行排序

        Collections.sort(webSecurityConfigurers, WebSecurityConfiguration.AnnotationAwareOrderComparator.INSTANCE);

        Integer previousOrder = null;

        Object previousConfig = null;

        //迭代所有配置类的实例 判断其order必须唯一

        Iterator var5;

        SecurityConfigurer config;

        for(var5 = webSecurityConfigurers.iterator(); var5.hasNext(); previousConfig = config) {

            config = (SecurityConfigurer)var5.next();

            Integer order = Integer.valueOf(WebSecurityConfiguration.AnnotationAwareOrderComparator.lookupOrder(config));

            if(previousOrder != null && previousOrder.equals(order)) {

                throw new IllegalStateException("@Order on WebSecurityConfigurers must be unique. Order of " + order + " was already used on " + previousConfig + ", so it cannot be used on " + config + " too.");

            }

            previousOrder = order;

        }

        //将所有的配置实例添加到创建的webSecutity对象中

        var5 = webSecurityConfigurers.iterator();

        while(var5.hasNext()) {

            config = (SecurityConfigurer)var5.next();

            this.webSecurity.apply(config);

        }

        //将webSercurityConfigures 实例放入该对象的webSecurityConfigurers属性中

        this.webSecurityConfigurers = webSecurityConfigurers;

    }

}

2.1、 setFilterChainProxySecurityConfigurer（）方法

@Value("#{@autowiredWebSecurityConfigurersIgnoreParents.getWebSecurityConfigurers()}") List<SecurityConfigurer<Filter, WebSecurity>> webSecurityConfigurers

该参数webSecurityConfigurers会将所有的配置实例放入该形参中

该方法中主要执行如下

1、创建webSecurity对象

2、主要检验了配置实例的order顺序（order唯一否则会报错）

3、将所有的配置实例存放进入到webSecurity对象中，其中配置实例中含有我们自定义业务的权限控制配置信息

2.2、springSecurityFilterChain()方法

调用springSecurityFilterChain()方法，这个方法会判断我们上一个方法中有没有获取到webSecurityConfigurers，没有的话这边会创建一个WebSecurityConfigurerAdapter实例，并追加到websecurity中。接着调用websecurity的build方法。实际调用的是websecurity的父类AbstractSecurityBuilder的build方法，最终返回一个名称为springSecurityFilterChain的过滤器链。里面有众多Filter(springSecurity其实就是依靠很多的Filter来拦截url从而实现权限的控制的安全框架)

3、AbstractSecurityBuilder类

public abstract class AbstractSecurityBuilder<O> implements SecurityBuilder<O> {

    private AtomicBoolean building = new AtomicBoolean();

    private O object;

    //调用build方法来返回过滤器链，还是调用SecurityBuilder的dobuild()方法

    public final O build() throws Exception {

        if(this.building.compareAndSet(false, true)) {

            this.object = this.doBuild();

            return this.object;

        } else {

            throw new AlreadyBuiltException("This object has already been built");

        }

    }

   //...省略部分代码

}

3.1 调用子类的doBuild()方法

public abstract class AbstractConfiguredSecurityBuilder<O, B extends SecurityBuilder<O>> extends AbstractSecurityBuilder<O> {

    private final Log logger;

    private final LinkedHashMap<Class<? extends SecurityConfigurer<O, B>>, List<SecurityConfigurer<O, B>>> configurers;

    private final List<SecurityConfigurer<O, B>> configurersAddedInInitializing;

    private final Map<Class<? extends Object>, Object> sharedObjects;

    private final boolean allowConfigurersOfSameType;

    private AbstractConfiguredSecurityBuilder.BuildState buildState;

    private ObjectPostProcessor<Object> objectPostProcessor;

    //doBuild()核心方法 init(),configure(),perFormBuild()

    protected final O doBuild() throws Exception {

        LinkedHashMap var1 = this.configurers;

        synchronized(this.configurers) {

            this.buildState = AbstractConfiguredSecurityBuilder.BuildState.INITIALIZING;

            this.beforeInit();

            this.init();

            this.buildState = AbstractConfiguredSecurityBuilder.BuildState.CONFIGURING;

            this.beforeConfigure();

            this.configure();

            this.buildState = AbstractConfiguredSecurityBuilder.BuildState.BUILDING;

            O result = this.performBuild();

            this.buildState = AbstractConfiguredSecurityBuilder.BuildState.BUILT;

            return result;

        }

    }

    protected abstract O performBuild() throws Exception;

    //调用init方法 调用配置类WebSecurityConfigurerAdapter的init()方法

    private void init() throws Exception {

        Collection<SecurityConfigurer<O, B>> configurers = this.getConfigurers();

        Iterator var2 = configurers.iterator();

        SecurityConfigurer configurer;

        while(var2.hasNext()) {

            configurer = (SecurityConfigurer)var2.next();

            configurer.init(this);

        }

        var2 = this.configurersAddedInInitializing.iterator();

        while(var2.hasNext()) {

            configurer = (SecurityConfigurer)var2.next();

            configurer.init(this);

        }

    }

    private void configure() throws Exception {

        Collection<SecurityConfigurer<O, B>> configurers = this.getConfigurers();

        Iterator var2 = configurers.iterator();

        while(var2.hasNext()) {

            SecurityConfigurer<O, B> configurer = (SecurityConfigurer)var2.next();

            configurer.configure(this);

        }

    }

    private Collection<SecurityConfigurer<O, B>> getConfigurers() {

        List<SecurityConfigurer<O, B>> result = new ArrayList();

        Iterator var2 = this.configurers.values().iterator();

        while(var2.hasNext()) {

            List<SecurityConfigurer<O, B>> configs = (List)var2.next();

            result.addAll(configs);

        }

        return result;

    }

    //...省略部分代码

}

3.2 先调用本类的init()方法

build过程主要分三步，init->configure->peformBuild

1 init方法做了两件事，一个就是调用getHttp()方法获取一个http实例，并通过web.addSecurityFilterChainBuilder方法把获取到的实例赋值给WebSecurity的securityFilterChainBuilders属性，这个属性在我们执行build的时候会用到，第二个就是为WebSecurity追加了一个postBuildAction，在build都完成后从http中拿出FilterSecurityInterceptor对象并赋值给WebSecurity。
2 getHttp()方法，这个方法在当我们使用默认配置时（大多数情况下）会为我们追加各种SecurityConfigurer的具体实现类到httpSecurity中，如exceptionHandling()方法会追加一个ExceptionHandlingConfigurer，sessionManagement()方法会追加一个SessionManagementConfigurer,securityContext()方法会追加一个SecurityContextConfigurer对象，这些SecurityConfigurer的具体实现类最终会为我们配置各种具体的filter。
3 另外getHttp()方法的最后会调用configure(http)，这个方法也是我们继承WebSecurityConfigurerAdapter类后最可能会重写的方法。
4 configure(HttpSecurity http)方法，默认的configure(HttpSecurity http)方法继续向httpSecurity类中追加SecurityConfigurer的具体实现类，如authorizeRequests()方法追加一个ExpressionUrlAuthorizationConfigurer，formLogin()方法追加一个FormLoginConfigurer。其中ExpressionUrlAuthorizationConfigurer这个实现类比较重要，因为他会给我们创建一个非常重要的对象FilterSecurityInterceptor对象，FormLoginConfigurer对象比较简单，但是也会为我们提供一个在安全认证过程中经常用到会用的一个Filter：UsernamePasswordAuthenticationFilter。

以上三个方法就是WebSecurityConfigurerAdapter类中init方法的主要逻辑，

public abstract class WebSecurityConfigurerAdapter implements

   WebSecurityConfigurer<WebSecurity> {

    public void init(final WebSecurity web) throws Exception {

        final HttpSecurity http = this.getHttp();

        web.addSecurityFilterChainBuilder(http).postBuildAction(new Runnable() {

            public void run() {

                FilterSecurityInterceptor securityInterceptor = (FilterSecurityInterceptor)http.getSharedObject(FilterSecurityInterceptor.class);

                web.securityInterceptor(securityInterceptor);

            }

        });

    }

 protected final HttpSecurity getHttp() throws Exception {

        if(this.http != null) {

            return this.http;

        } else {

            DefaultAuthenticationEventPublisher eventPublisher = (DefaultAuthenticationEventPublisher)this.objectPostProcessor.postProcess(new DefaultAuthenticationEventPublisher());

//添加认证的事件的发布者

this.localConfigureAuthenticationBldr.authenticationEventPublisher(eventPublisher);

//获取AuthenticationManager对象其中一至多个进行认证处理的对象实例，后面会进行讲解

AuthenticationManager authenticationManager = this.authenticationManager();

            this.authenticationBuilder.parentAuthenticationManager(authenticationManager);

            Map<Class<? extends Object>, Object> sharedObjects = this.createSharedObjects();

            this.http = new HttpSecurity(this.objectPostProcessor, this.authenticationBuilder, sharedObjects);

            if(!this.disableDefaults) {

                ((HttpSecurity)((DefaultLoginPageConfigurer)((HttpSecurity)((HttpSecurity)((HttpSecurity)((HttpSecurity)((HttpSecurity)((HttpSecurity)((HttpSecurity)((HttpSecurity)this.http.csrf().and()).addFilter(new WebAsyncManagerIntegrationFilter()).exceptionHandling().and()).headers().and()).sessionManagement().and()).securityContext().and()).requestCache().and()).anonymous().and()).servletApi().and()).apply(new DefaultLoginPageConfigurer())).and()).logout();

                ClassLoader classLoader = this.context.getClassLoader();

                List<AbstractHttpConfigurer> defaultHttpConfigurers = SpringFactoriesLoader.loadFactories(AbstractHttpConfigurer.class, classLoader);

                Iterator var6 = defaultHttpConfigurers.iterator();

                while(var6.hasNext()) {

                    AbstractHttpConfigurer configurer = (AbstractHttpConfigurer)var6.next();

                    this.http.apply(configurer);

                }

            }

            //最终调用我们的继承的WebSecurityConfigurerAdapter中重写的configure()

            //将我们业务相关的权限配置规则信息进行初始化操作

            this.configure(this.http);

            return this.http;

        }

    }

 protected AuthenticationManager authenticationManager() throws Exception {

        if(!this.authenticationManagerInitialized) {

            this.configure(this.localConfigureAuthenticationBldr);

            if(this.disableLocalConfigureAuthenticationBldr) {

                this.authenticationManager = this.authenticationConfiguration.getAuthenticationManager();

            } else {

                this.authenticationManager = (AuthenticationManager)this.localConfigureAuthenticationBldr.build();

            }

            this.authenticationManagerInitialized = true;

        }

        return this.authenticationManager;

    }

}

3.3、第二步configure

configure方法最终也调用到了WebSecurityConfigurerAdapter的configure(WebSecurity web)方法，默认实现中这个是一个空方法，具体应用中也经常重写这个方法来实现特定需求。

3.4、第三步 peformBuild

具体的实现逻辑在WebSecurity类中
这个方法中最主要的任务就是遍历securityFilterChainBuilders属性中的SecurityBuilder对象，并调用他的build方法。

这个securityFilterChainBuilders属性我们前面也有提到过，就是在WebSecurityConfigurerAdapter类的init方法中获取http后赋值给了WebSecurity。因此这个地方就是调用httpSecurity的build方法。
httpSecurity的build方式向其中追加一个个过滤器



public final class WebSecurity extends AbstractConfiguredSecurityBuilder<Filter, WebSecurity> implements SecurityBuilder<Filter>, ApplicationContextAware {

...省略部分代码
<span class="hljs-comment">//调用该方法通过securityFilterChainBuilder.build()方法来创建securityFilter过滤器</span>

<span class="hljs-comment">//并添加到securityFilterChains对象中，包装成FilterChainProxy 返回</span>

<span class="hljs-function"><span class="hljs-keyword">protected</span> Filter <span class="hljs-title">performBuild</span><span class="hljs-params">()</span> <span class="hljs-keyword">throws</span> Exception </span>{

    Assert.state(!<span class="hljs-keyword">this</span>.securityFilterChainBuilders.isEmpty(), <span class="hljs-string">"At least one SecurityBuilder&lt;? extends SecurityFilterChain&gt; needs to be specified. Typically this done by adding a @Configuration that extends WebSecurityConfigurerAdapter. More advanced users can invoke "</span> + WebSecurity.class.getSimpleName() + <span class="hljs-string">".addSecurityFilterChainBuilder directly"</span>);

    <span class="hljs-keyword">int</span> chainSize = <span class="hljs-keyword">this</span>.ignoredRequests.size() + <span class="hljs-keyword">this</span>.securityFilterChainBuilders.size();

    List&lt;SecurityFilterChain&gt; securityFilterChains = <span class="hljs-keyword">new</span> ArrayList(chainSize);

    Iterator var3 = <span class="hljs-keyword">this</span>.ignoredRequests.iterator();

    <span class="hljs-keyword">while</span>(var3.hasNext()) {

        RequestMatcher ignoredRequest = (RequestMatcher)var3.next();

        securityFilterChains.add(<span class="hljs-keyword">new</span> DefaultSecurityFilterChain(ignoredRequest, <span class="hljs-keyword">new</span> Filter[<span class="hljs-number">0</span>]));

    }

    var3 = <span class="hljs-keyword">this</span>.securityFilterChainBuilders.iterator();

    <span class="hljs-keyword">while</span>(var3.hasNext()) {

        SecurityBuilder&lt;? extends SecurityFilterChain&gt; securityFilterChainBuilder = (SecurityBuilder)var3.next();

        securityFilterChains.add(securityFilterChainBuilder.build());

    }

    FilterChainProxy filterChainProxy = <span class="hljs-keyword">new</span> FilterChainProxy(securityFilterChains);

    <span class="hljs-keyword">if</span>(<span class="hljs-keyword">this</span>.httpFirewall != <span class="hljs-keyword">null</span>) {

        filterChainProxy.setFirewall(<span class="hljs-keyword">this</span>.httpFirewall);

    }

    filterChainProxy.afterPropertiesSet();

    Filter result = filterChainProxy;

    <span class="hljs-keyword">if</span>(<span class="hljs-keyword">this</span>.debugEnabled) {

        <span class="hljs-keyword">this</span>.logger.warn(<span class="hljs-string">"\n\n********************************************************************\n**********        Security debugging is enabled.       *************\n**********    This may include sensitive information.  *************\n**********      Do not use in a production system!     *************\n********************************************************************\n\n"</span>);

        result = <span class="hljs-keyword">new</span> DebugFilter(filterChainProxy);

    }

    <span class="hljs-keyword">this</span>.postBuildAction.run();

    <span class="hljs-keyword">return</span> (Filter)result;

}


}

4、举例说明如何将一个Configurer转换为filter

ExpressionUrlAuthorizationConfigurer的继承关系

ExpressionUrlAuthorizationConfigurer->AbstractInterceptUrlConfigurer->AbstractHttpConfigurer->SecurityConfigurerAdapter->SecurityConfigurer

对应的init方法在SecurityConfigurerAdapter类中，是个空实现，什么也没有做，configure方法在SecurityConfigurerAdapter类中也有一个空实现，在AbstractInterceptUrlConfigurer类中进行了重写

Abstractintercepturlconfigurer.java代码

@Override  

    public void configure(H http) throws Exception {  

        FilterInvocationSecurityMetadataSource metadataSource = createMetadataSource(http);  

        if (metadataSource == null) {  

            return;  

        }  

        FilterSecurityInterceptor securityInterceptor = createFilterSecurityInterceptor(  

                http, metadataSource, http.getSharedObject(AuthenticationManager.class));  

        if (filterSecurityInterceptorOncePerRequest != null) {  

            securityInterceptor  

                    .setObserveOncePerRequest(filterSecurityInterceptorOncePerRequest);  

        }  

        securityInterceptor = postProcess(securityInterceptor);  

        http.addFilter(securityInterceptor);  

        http.setSharedObject(FilterSecurityInterceptor.class, securityInterceptor);  

    }  

...  

private AccessDecisionManager createDefaultAccessDecisionManager(H http) {  

        AffirmativeBased result = new AffirmativeBased(getDecisionVoters(http));  

        return postProcess(result);  

    }  

...  

private FilterSecurityInterceptor createFilterSecurityInterceptor(H http,  

            FilterInvocationSecurityMetadataSource metadataSource,  

            AuthenticationManager authenticationManager) throws Exception {  

        FilterSecurityInterceptor securityInterceptor = new FilterSecurityInterceptor();  

        securityInterceptor.setSecurityMetadataSource(metadataSource);  

        securityInterceptor.setAccessDecisionManager(getAccessDecisionManager(http));  

        securityInterceptor.setAuthenticationManager(authenticationManager);  

        securityInterceptor.afterPropertiesSet();  

        return securityInterceptor;  

    }

4.1、在这个类的configure中创建了一个FilterSecurityInterceptor，并且也可以明确看到spring security默认给我们创建的AccessDecisionManager是AffirmativeBased。

4.2、.最后再看下HttpSecurity类执行build的最后一步 performBuild，这个方法就是在HttpSecurity中实现的

Httpsecurity.java代码

@Override  

    protected DefaultSecurityFilterChain performBuild() throws Exception {  

        Collections.sort(filters, comparator);  

        return new DefaultSecurityFilterChain(requestMatcher, filters);  

    }

可以看到，这个类只是把我们追加到HttpSecurity中的security进行了排序，用的排序类是FilterComparator，从而保证我们的filter按照正确的顺序执行。接着将filters构建成filterChian返回。在前面WebSecurity的performBuild方法中，这个返回值会被包装成FilterChainProxy，并作为WebSecurity的build方法的放回值。从而以springSecurityFilterChain这个名称注册到springContext中（在WebSecurityConfiguration中做的）

4.3.在WebSecurity的performBuild方法的最后一步还执行了一个postBuildAction.run，这个方法也是spring security给我们提供的一个hooks，可以在build完成后再做一些事情，比如我们在WebSecurityConfigurerAdapter类的init方法中我们利用这个hook在构建完成后将FilterSecurityInterceptor赋值给了webSecurity类的filterSecurityInterceptor属性

三、用户登录的验证和授权过程

1、用户一次完整的登录验证和授权，是一个请求经过层层拦截器从而实现权限控制，整个web端配置为DelegatingFilterProxy（springSecurity的委托过滤其代理类），它并不实现真正的过滤，而是所有过滤器链的代理类，真正执行拦截处理的是由spring 容器管理的个个filter bean组成的filterChain.

调用实际的FilterChainProxy 的doFilterInternal()方法去获取所有的拦截器并进行过滤处理如下是DelegatingFilterProxy的doFilter（）方法

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

        Filter delegateToUse = this.delegate;

        if(delegateToUse == null) {

            Object var5 = this.delegateMonitor;

            synchronized(this.delegateMonitor) {

                delegateToUse = this.delegate;

                if(delegateToUse == null) {

                    WebApplicationContext wac = this.findWebApplicationContext();

                    if(wac == null) {

                        throw new IllegalStateException("No WebApplicationContext found: no ContextLoaderListener or DispatcherServlet registered?");

                    }

                    delegateToUse = this.initDelegate(wac);

                }

                this.delegate = delegateToUse;

            }

        }

//调用实际的FilterChainProxy 的doFilterInternal()方法 去获取所有的拦截器并进行过滤处理

        this.invokeDelegate(delegateToUse, request, response, filterChain);

    }

调用实际的FilterChainProxy 的doFilter()方法去获取所有的拦截器并进行过滤处理。

2、FilterChainProxy类

最终调用FilterChainProxy 的doFilterInternal()方法，获取所有的过滤器实例

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

        boolean clearContext = request.getAttribute(FILTER_APPLIED) == null;

        if(clearContext) {

            try {

                request.setAttribute(FILTER_APPLIED, Boolean.TRUE);

                //doFilter 调用doFilterInternal方法

                this.doFilterInternal(request, response, chain);

            } finally {

                SecurityContextHolder.clearContext();

                request.removeAttribute(FILTER_APPLIED);

            }

        } else {

            this.doFilterInternal(request, response, chain);

        }

    }

    private void doFilterInternal(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {

        FirewalledRequest fwRequest = this.firewall.getFirewalledRequest((HttpServletRequest)request);

        HttpServletResponse fwResponse = this.firewall.getFirewalledResponse((HttpServletResponse)response);

         //过去所有的过滤器

        List<Filter> filters = this.getFilters((HttpServletRequest)fwRequest);

        if(filters != null && filters.size() != 0) {

            FilterChainProxy.VirtualFilterChain vfc = new FilterChainProxy.VirtualFilterChain(fwRequest, chain, filters);

            vfc.doFilter(fwRequest, fwResponse);

        } else {

            if(logger.isDebugEnabled()) {

                logger.debug(UrlUtils.buildRequestUrl(fwRequest) + (filters == null?" has no matching filters":" has an empty filter list"));

            }

            fwRequest.reset();

            chain.doFilter(fwRequest, fwResponse);

        }

    }

  private List<Filter> getFilters(HttpServletRequest request) {

       //遍历所有的matcher类 如果支持就继续获取

        Iterator var2 = this.filterChains.iterator();

        SecurityFilterChain chain;

        do {

            if(!var2.hasNext()) {

                return null;

            }

            chain = (SecurityFilterChain)var2.next();

        } while(!chain.matches(request));

        //后去匹配中的所有过滤器

        return chain.getFilters();

    }

如上其实是获取到本次请求的所有filter 并安装指定顺序进行执行doFilter()方法

这是笔者本次业务请求所要执行的所有过滤器

WebAsyncManagerIntegrationFilter
SecurityContextPersistenceFilter
HeaderWriterFilter
LogoutFilter
UsernamePasswordAuthenticationFilter
RequestCacheAwareFilter
SecurityContextHolderAwareRequestFilter
AnonymousAuthenticationFilter
SessionManagementFilter
ExceptionTranslationFilter
FilterSecurityInterceptor

关于springSecutity拦截器的介绍请参考如下链接地址

https://blog.csdn.net/dushiwodecuo/article/details/78913113

http://blog.didispace.com/xjf-spring-security-4/

https://www.cnblogs.com/HHR-SUN/p/7095720.html

https://blog.csdn.net/zheng963/article/details/50427320

https://blog.csdn.net/m0_37834471/article/details/81142246

https://www.cnblogs.com/mingluosunshan/p/5485259.html

原文地址：https://blog.csdn.net/liushangzaibeijing/article/details/81220610