本篇目标是解析WebSecurityConfiguration是如何初始化的
首先，看下他的源码。
/**
* Uses a {@link WebSecurity} to create the {@link FilterChainProxy} that performs the web
* based security for Spring Security. It then exports the necessary beans. Customizations
* can be made to {@link WebSecurity} by extending {@link WebSecurityConfigurerAdapter}
* and exposing it as a {@link Configuration} or implementing
* {@link WebSecurityConfigurer} and exposing it as a {@link Configuration}. This
* configuration is imported when using {@link EnableWebSecurity}.
*
* @see EnableWebSecurity
* @see WebSecurity
*
* @author Rob Winch
* @author Keesun Baik
* @since 3.2
*/
@Configuration
public class WebSecurityConfiguration implements ImportAware, BeanClassLoaderAware {
private WebSecurity webSecurity;
private Boolean debugEnabled;
private List<SecurityConfigurer<Filter, WebSecurity>> webSecurityConfigurers;
private ClassLoader beanClassLoader;
@Autowired(required = false)
private ObjectPostProcessor<Object> objectObjectPostProcessor;
@Bean
public static DelegatingApplicationListener delegatingApplicationListener() {
return new DelegatingApplicationListener();
}
@Bean
@DependsOn(AbstractSecurityWebApplicationInitializer.DEFAULT_FILTER_NAME)
public SecurityExpressionHandler<FilterInvocation> webSecurityExpressionHandler() {
return webSecurity.getExpressionHandler();
}
/**
* Creates the Spring Security Filter Chain
* @return
* @throws Exception
*/
@Bean(name = AbstractSecurityWebApplicationInitializer.DEFAULT_FILTER_NAME)
public Filter springSecurityFilterChain() throws Exception {
boolean hasConfigurers = webSecurityConfigurers != null
&& !webSecurityConfigurers.isEmpty();
if (!hasConfigurers) {
WebSecurityConfigurerAdapter adapter = objectObjectPostProcessor
.postProcess(new WebSecurityConfigurerAdapter() {
});
webSecurity.apply(adapter);
}
return webSecurity.build();
}
/**
* Creates the {@link WebInvocationPrivilegeEvaluator} that is necessary for the JSP
* tag support.
* @return the {@link WebInvocationPrivilegeEvaluator}
* @throws Exception
*/
@Bean
@DependsOn(AbstractSecurityWebApplicationInitializer.DEFAULT_FILTER_NAME)
public WebInvocationPrivilegeEvaluator privilegeEvaluator() throws Exception {
return webSecurity.getPrivilegeEvaluator();
}
/**
* Sets the {@code <SecurityConfigurer<FilterChainProxy, WebSecurityBuilder>}
* instances used to create the web configuration.
*
* @param objectPostProcessor the {@link ObjectPostProcessor} used to create a
* {@link WebSecurity} instance
* @param webSecurityConfigurers the
* {@code <SecurityConfigurer<FilterChainProxy, WebSecurityBuilder>} instances used to
* create the web configuration
* @throws Exception
*/
@Autowired(required = false)
public void setFilterChainProxySecurityConfigurer(
ObjectPostProcessor<Object> objectPostProcessor,
@Value("#{@autowiredWebSecurityConfigurersIgnoreParents.getWebSecurityConfigurers()}") List<SecurityConfigurer<Filter, WebSecurity>> webSecurityConfigurers)
throws Exception {
webSecurity = objectPostProcessor
.postProcess(new WebSecurity(objectPostProcessor));
if (debugEnabled != null) {
webSecurity.debug(debugEnabled);
}
Collections.sort(webSecurityConfigurers, AnnotationAwareOrderComparator.INSTANCE);
Integer previousOrder = null;
Object previousConfig = null;
for (SecurityConfigurer<Filter, WebSecurity> config : webSecurityConfigurers) {
Integer order = 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;
previousConfig = config;
}
for (SecurityConfigurer<Filter, WebSecurity> webSecurityConfigurer : webSecurityConfigurers) {
webSecurity.apply(webSecurityConfigurer);
}
this.webSecurityConfigurers = webSecurityConfigurers;
}
@Bean
public AutowiredWebSecurityConfigurersIgnoreParents autowiredWebSecurityConfigurersIgnoreParents(
ConfigurableListableBeanFactory beanFactory) {
return new AutowiredWebSecurityConfigurersIgnoreParents(beanFactory);
}
/**
* A custom verision of the Spring provided AnnotationAwareOrderComparator that uses
* {@link AnnotationUtils#findAnnotation(Class, Class)} to look on super class
* instances for the {@link Order} annotation.
*
* @author Rob Winch
* @since 3.2
*/
private static class AnnotationAwareOrderComparator extends OrderComparator {
private static final AnnotationAwareOrderComparator INSTANCE = new AnnotationAwareOrderComparator();
@Override
protected int getOrder(Object obj) {
return lookupOrder(obj);
}
private static int lookupOrder(Object obj) {
if (obj instanceof Ordered) {
return ((Ordered) obj).getOrder();
}
if (obj != null) {
Class<?> clazz = (obj instanceof Class ? (Class<?>) obj : obj.getClass());
Order order = AnnotationUtils.findAnnotation(clazz, Order.class);
if (order != null) {
return order.value();
}
}
return Ordered.LOWEST_PRECEDENCE;
}
}
/*
* (non-Javadoc)
*
* @see org.springframework.context.annotation.ImportAware#setImportMetadata(org.
* springframework.core.type.AnnotationMetadata)
*/
public void setImportMetadata(AnnotationMetadata importMetadata) {
Map<String, Object> enableWebSecurityAttrMap = importMetadata
.getAnnotationAttributes(EnableWebSecurity.class.getName());
AnnotationAttributes enableWebSecurityAttrs = AnnotationAttributes
.fromMap(enableWebSecurityAttrMap);
debugEnabled = enableWebSecurityAttrs.getBoolean("debug");
if (webSecurity != null) {
webSecurity.debug(debugEnabled);
}
}
/*
* (non-Javadoc)
*
* @see
* org.springframework.beans.factory.BeanClassLoaderAware#setBeanClassLoader(java.
* lang.ClassLoader)
*/
public void setBeanClassLoader(ClassLoader classLoader) {
this.beanClassLoader = classLoader;
}
}
如这个类开头的注释写的一样，这个类的最后会生成一个FilterChainProxy类（一个Fliter），作为过滤器（链）来处理一个请求进入spring后进行的认证操作。我们挑着这里面比较重要的步骤进行分析下。
（一）AutowiredWebSecurityConfigurersIgnoreParents初始化
@Bean
public AutowiredWebSecurityConfigurersIgnoreParents autowiredWebSecurityConfigurersIgnoreParents(
ConfigurableListableBeanFactory beanFactory) {
return new AutowiredWebSecurityConfigurersIgnoreParents(beanFactory);
}
这个类有一个获取所有WebSecurityConfigurer子类实例的方法
public List<SecurityConfigurer<Filter, WebSecurity>> getWebSecurityConfigurers() {
List<SecurityConfigurer<Filter, WebSecurity>> webSecurityConfigurers = new ArrayList<SecurityConfigurer<Filter, WebSecurity>>();
Map<String, WebSecurityConfigurer> beansOfType = beanFactory
.getBeansOfType(WebSecurityConfigurer.class);
for (Entry<String, WebSecurityConfigurer> entry : beansOfType.entrySet()) {
webSecurityConfigurers.add(entry.getValue());
}
return webSecurityConfigurers;
}
这个类的用途在下面
（二）WebSecurity实例化以及基本配置的设置
@Autowired(required = false) public void setFilterChainProxySecurityConfigurer( ObjectPostProcessor<Object> objectPostProcessor,
//利用上面的初始化的AutowiredWebSecurityConfigurersIgnoreParents的getWebSecurityConfigurers方法获取我们的Spring security的配置 @Value("#{@autowiredWebSecurityConfigurersIgnoreParents.getWebSecurityConfigurers()}") List<SecurityConfigurer<Filter, WebSecurity>> webSecurityConfigurers) throws Exception {
//创建WebSecurity实例 webSecurity = objectPostProcessor .postProcess(new WebSecurity(objectPostProcessor)); if (debugEnabled != null) { webSecurity.debug(debugEnabled); } Collections.sort(webSecurityConfigurers, AnnotationAwareOrderComparator.INSTANCE); Integer previousOrder = null; Object previousConfig = null; for (SecurityConfigurer<Filter, WebSecurity> config : webSecurityConfigurers) { Integer order = 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; previousConfig = config; } for (SecurityConfigurer<Filter, WebSecurity> webSecurityConfigurer : webSecurityConfigurers) { webSecurity.apply(webSecurityConfigurer); } this.webSecurityConfigurers = webSecurityConfigurers; }
这个方法主要的操作是实例化WebSecurity，并将Spring security的配置设置为他的webSecurityConfigurers属性的值
这边为了方便查看之前的配置，我们把配置类的代码也插入到这边
@Configuration
@EnableWebSecurity
public class WebSecurityConfig extends WebSecurityConfigurerAdapter {
@Override
protected void configure(HttpSecurity http) throws Exception {
http
.authorizeRequests()
.antMatchers("/", "/home").permitAll()
.anyRequest().authenticated()
.and()
.formLogin()
.loginPage("/login")
.permitAll()
.and()
.logout()
.permitAll();
}
@Bean
@Override
public UserDetailsService userDetailsService() {
UserDetails user =
User.withDefaultPasswordEncoder()
.username("user")
.password("password")
.roles("USER")
.build();
return new InMemoryUserDetailsManager(user);
}
}
（三）springSecurityFilterChain初始化
@Bean(name = AbstractSecurityWebApplicationInitializer.DEFAULT_FILTER_NAME)
public Filter springSecurityFilterChain() throws Exception {
//step 1
boolean hasConfigurers = webSecurityConfigurers != null
&& !webSecurityConfigurers.isEmpty();
if (!hasConfigurers) {
WebSecurityConfigurerAdapter adapter = objectObjectPostProcessor
.postProcess(new WebSecurityConfigurerAdapter() {
});
webSecurity.apply(adapter);
}
//step 2
return webSecurity.build();
}
就是这个方法，将最核心的Spring security的过滤器（链）初始化了。
这个方法的第一步就是判断当前是否配置了webSecurityConfigurers，如果没有，则会生成一个默认的：new WebSecurityConfigurerAdapter()，这个也就可以解释我刚接触Spring security时的困惑（为什么引入了Spring security的依赖后，我基本的配置类没写，我的接口就不能调用了？答：这边给了个默认的配置）
第二步就会对webSecurity进行构建：webSecurity.build()；
首先调用的是AbstractSecurityBuilder的build()方法
public final O build() throws Exception {
if (this.building.compareAndSet(false, true)) {
this.object = doBuild();
return this.object;
}
throw new AlreadyBuiltException("This object has already been built");
}
然后调用doBuild()方法，doBuild()是在AbstractSecurityBuilder的子类AbstractConfiguredSecurityBuilder中实现的
@Override
protected final O doBuild() throws Exception {
synchronized (configurers) {
buildState = BuildState.INITIALIZING;
beforeInit();
init();
buildState = BuildState.CONFIGURING;
beforeConfigure();
configure();
buildState = BuildState.BUILDING;
O result = performBuild();
buildState = BuildState.BUILT;
return result;
}
}
这是一个很典型的模版方法模式，其中的beforeInit()和beforeConfigure()皆为钩子方法，这里默认也没有任何实现，我们暂时不用关注，主要需要注意的是init()、configure()和performBuild()方法。下面我们一个个分析这几个方法。
1、init方法
private void init() throws Exception {
Collection<SecurityConfigurer<O, B>> configurers = getConfigurers();
for (SecurityConfigurer<O, B> configurer : configurers) {
configurer.init((B) this);
}
for (SecurityConfigurer<O, B> configurer : configurersAddedInInitializing) {
configurer.init((B) this);
}
}
这边的configurer.init((B) this);调用的是WebSecurityConfigurerAdapter的init方法，源码如下
public void init(final WebSecurity web) throws Exception {
final HttpSecurity http = getHttp();（1）
web.addSecurityFilterChainBuilder(http).postBuildAction(new Runnable() {
public void run() {
FilterSecurityInterceptor securityInterceptor = http
.getSharedObject(FilterSecurityInterceptor.class);
web.securityInterceptor(securityInterceptor);
}
});（2）
}
第（1）步是初始化了HttpSecurity，第（2）步的前半部分web.addSecurityFilterChainBuilder(http)则将这个HttpSecurity加入到了webSecurity的
private final List<SecurityBuilder<? extends SecurityFilterChain>> securityFilterChainBuilders = new ArrayList<SecurityBuilder<? extends SecurityFilterChain>>();
这个属性中，后面performBuild的时候会用到；
这里的第（1）步其实很关键，一下子初始化了2个核心。这里再多说一句，针对不同的WebSecurityConfigurerAdapter的实现类，也就是配置，他们各自的HttpSecurity是各自的。
protected final HttpSecurity getHttp() throws Exception {
if (http != null) {
return http;
}
DefaultAuthenticationEventPublisher eventPublisher = objectPostProcessor
.postProcess(new DefaultAuthenticationEventPublisher());
localConfigureAuthenticationBldr.authenticationEventPublisher(eventPublisher);
AuthenticationManager authenticationManager = authenticationManager();（1）
authenticationBuilder.parentAuthenticationManager(authenticationManager);
Map<Class<? extends Object>, Object> sharedObjects = createSharedObjects();
http = new HttpSecurity(objectPostProcessor, authenticationBuilder,
sharedObjects);（2）
if (!disableDefaults) {
// @formatter:off
http
.csrf().and()（3）
.addFilter(new WebAsyncManagerIntegrationFilter())（4）
.exceptionHandling().and()（5）
.headers().and()（6）
.sessionManagement().and()（7）
.securityContext().and()（8）
.requestCache().and()（9）
.anonymous().and()（10）
.servletApi().and()（11）
.apply(new DefaultLoginPageConfigurer<HttpSecurity>()).and()（12）
.logout();（13）
// @formatter:on
ClassLoader classLoader = this.context.getClassLoader();
List<AbstractHttpConfigurer> defaultHttpConfigurers =
SpringFactoriesLoader.loadFactories(AbstractHttpConfigurer.class, classLoader);
for(AbstractHttpConfigurer configurer : defaultHttpConfigurers) {
http.apply(configurer);
}
}
configure(http);
return http;
}
这个方法的第（1）步获取了AuthenticationManager，而如果AuthenticationManager没有被初始化，则这里则对AuthenticationManager进行了初始化，后面的第（2）步则实例化了HttpSecurity，第（3）-（13）步则给HttpSecurity加了些configure和给WebSecurity加了些Filter。下面我们着重看第（1）步，后面的几步会在后面的不同Filter的文章中分别交代。下面看下authenticationManager()方法
protected AuthenticationManager authenticationManager() throws Exception {
if (!authenticationManagerInitialized) {
//提供了自定义配置的地方，如果在我们的配置类中override了configure(AuthenticationManagerBuilder auth)方法，则就是在这里生效的
configure(localConfigureAuthenticationBldr);
if (disableLocalConfigureAuthenticationBldr) {
//提供了默认的配置AuthenticationManager的方法，一般我们什么都不配置，则走的这里的方法
authenticationManager = authenticationConfiguration
.getAuthenticationManager();
}
else {
authenticationManager = localConfigureAuthenticationBldr.build();
}
authenticationManagerInitialized = true;
}
return authenticationManager;
}
这个方法的作用写在了注释中，我们继续看authenticationConfiguration.getAuthenticationManager();方法
public AuthenticationManager getAuthenticationManager() throws Exception {
if (this.authenticationManagerInitialized) {
return this.authenticationManager;
}
//new了一个AuthenticationManagerBuilder实例，执行了new AuthenticationManagerBuilder(objectPostProcessor)
AuthenticationManagerBuilder authBuilder = authenticationManagerBuilder(
this.objectPostProcessor);
if (this.buildingAuthenticationManager.getAndSet(true)) {
return new AuthenticationManagerDelegator(authBuilder);
}
for (GlobalAuthenticationConfigurerAdapter config : globalAuthConfigurers) {（1）
authBuilder.apply(config);
}
authenticationManager = authBuilder.build();（2）
if (authenticationManager == null) {
authenticationManager = getAuthenticationManagerBean();
}
this.authenticationManagerInitialized = true;
return authenticationManager;
}
这边核心的有2步，第（1）步是获取配置，第（2）步是我们熟悉的初始化节奏。而第一步的配置，默认有如下的配置，他们具体从哪来的，我们留到后面再讲解。
那么第（2）步就来到了AuthenticationManagerBuilder的build(),继而就是doBuild()，也就是我们上面的模版方法，这边我们再贴一次代码
protected final O doBuild() throws Exception {
synchronized (configurers) {
buildState = BuildState.INITIALIZING;
beforeInit();
init();
buildState = BuildState.CONFIGURING;
beforeConfigure();
configure();
buildState = BuildState.BUILDING;
O result = performBuild();
buildState = BuildState.BUILT;
return result;
}
}
这边最终返回的是ProviderManager，上面的init和configur我们先跳过分析，直接看这边的performBuild()
protected ProviderManager performBuild() throws Exception {
if (!isConfigured()) {
logger.debug("No authenticationProviders and no parentAuthenticationManager defined. Returning null.");
return null;
}
ProviderManager providerManager = new ProviderManager(authenticationProviders,
parentAuthenticationManager);
if (eraseCredentials != null) {
providerManager.setEraseCredentialsAfterAuthentication(eraseCredentials);
}
if (eventPublisher != null) {
providerManager.setAuthenticationEventPublisher(eventPublisher);
}
providerManager = postProcess(providerManager);
return providerManager;
}
这边可以看的出来ProviderManager是new出来的，而他最重要的则是后面的参数authenticationProviders，也就是List<AuthenticationProvider> authenticationProviders，他就是进行鉴权的核心实现。
AuthenticationManager的初始化，我们就先到这里，后面会有一篇文章再对这个过程进行详细梳理。
2、configure(WebSecurity web)方法
这边是对WebSecurity进行定制化的地方，这个方法相对init()来说就简单多了
默认来讲，如果我们在我们的配置类中未override这个方法，那么这里将什么都不发生，默认实现如下。
public void configure(WebSecurity web) throws Exception {
}
这里我们可以配置一些需要忽略的，也就是不需要认证的请求，如：
@Override
public void configure(WebSecurity web) throws Exception {
web.ignoring().antMatchers("/test/**");
}
这边的配置和下面的ignoredRequests.size()相对应。
3、performBuild()
这个方法将会真正的实例化Filter并返回
@Override
protected Filter performBuild() throws Exception {
Assert.state(
!securityFilterChainBuilders.isEmpty(),
"At least one SecurityBuilder<? extends SecurityFilterChain> needs to be specified. Typically this done by adding a @Configuration that extends WebSecurityConfigurerAdapter. More advanced users can invoke "
+ WebSecurity.class.getSimpleName()
+ ".addSecurityFilterChainBuilder directly");
int chainSize = ignoredRequests.size() + securityFilterChainBuilders.size();
List<SecurityFilterChain> securityFilterChains = new ArrayList<SecurityFilterChain>(
chainSize);
for (RequestMatcher ignoredRequest : ignoredRequests) {
securityFilterChains.add(new DefaultSecurityFilterChain(ignoredRequest));
}
//
for (SecurityBuilder<? extends SecurityFilterChain> securityFilterChainBuilder : securityFilterChainBuilders) {
securityFilterChains.add(securityFilterChainBuilder.build());（1）
}
FilterChainProxy filterChainProxy = new FilterChainProxy(securityFilterChains);(2)
if (httpFirewall != null) {
filterChainProxy.setFirewall(httpFirewall);
}
filterChainProxy.afterPropertiesSet();
Filter result = filterChainProxy;
if (debugEnabled) {
logger.warn("\n\n"
+ "********************************************************************\n"
+ "********** Security debugging is enabled. *************\n"
+ "********** This may include sensitive information. *************\n"
+ "********** Do not use in a production system! *************\n"
+ "********************************************************************\n\n");
result = new DebugFilter(filterChainProxy);
}
postBuildAction.run();
return result;
}
这里的第（1）步则是实例化SecurityFilterChain，加入到List<SecurityFilterChain> filterChains中，这里的securityFilterChainBuilder.build()实质上就是HttpSecurity进行build，这里的list中有多少值就看系统配置了多少个WebSecurityConfigurerAdapter，按照我们之前的配置，这里就一个。根据下面的类图，也就是调用的AbstractSecurityBuilder的build()方法
HttpSecurity的build我们发到下一篇文章。
第（2）步则将List<SecurityFilterChain> filterChains作为FilterChainProxy初始化的属性，初始化了FilterChainProxy，并返回了这个Filter。
至此，FilterChainProxy的初始化结束了，也就是Spring security的初始化结束了。