本文关注应用的安全方面，涉及校验以及授权方面，以springboot自带的security板块作为讲解的内容

实例

建议用户可直接路由至博主的先前博客spring security整合cas方案。本文则针对相关的源码作下简单的分析，方便笔者以及读者更深入的了解spring的security板块

@EnableWebSecurity

这个注解很精髓，基本上可以作为security的入口，笔者贴一下它的源码

@Retention(value = java.lang.annotation.RetentionPolicy.RUNTIME)
@Target(value = { java.lang.annotation.ElementType.TYPE })
@Documented
@Import({ WebSecurityConfiguration.class,SpringWebMvcImportSelector.class })
@EnableGlobalAuthentication
@Configuration
public @interface EnableWebSecurity {/*** Controls debugging support for Spring Security. Default is false.* @return if true, enables debug support with Spring Security*/boolean debug() default false;
}

可以分为三个部分来分析，
SpringWebMvcImportSelector-支持mvc的参数安全校验，替代了@EnableWebMvcSecurity注解
WebSecurityConfiguration-Web的安全配置
@EnableGlobalAuthentication-支持公共的认证校验

SpringWebMvcImportSelector

首先先看下其如何整合mvc的安全校验，其是一个ImportSelector接口，观察下其复写的方法

public String[] selectImports(AnnotationMetadata importingClassMetadata) {boolean webmvcPresent = ClassUtils.isPresent("org.springframework.web.servlet.DispatcherServlet",getClass().getClassLoader());return webmvcPresent? new String[] {"org.springframework.security.config.annotation.web.configuration.WebMvcSecurityConfiguration" }: new String[] {};}

由上述代码可知，在classpath环境中存在mvc的关键类DispatcherServlet时便会引入WebMvcSecurityConfiguration类，那么此类又配置了什么东西呢？
里面的代码很简单，但关键是其是WebMvcConfigurer接口的实现类，根据之前的文章提到，该接口主要是用于配置MVC的相关功能，比如参数处理器、返回值处理器、异常处理器等等。

而该类只是扩展了相应的参数处理器，我们可以看下源码

    @Override@SuppressWarnings("deprecation")public void addArgumentResolvers(List<HandlerMethodArgumentResolver> argumentResolvers) {// 支持@AuthenticationPrinciple参数注解校验AuthenticationPrincipalArgumentResolver authenticationPrincipalResolver = new AuthenticationPrincipalArgumentResolver();authenticationPrincipalResolver.setBeanResolver(beanResolver);argumentResolvers.add(authenticationPrincipalResolver);// 废弃argumentResolvers.add(new org.springframework.security.web.bind.support.AuthenticationPrincipalArgumentResolver());// csrf token参数argumentResolvers.add(new CsrfTokenArgumentResolver());}

针对@AuthenticationPrinciple注解的参数校验，本文不展开了，这里作下归纳

1. 带有@AuthenticationPrinciple注解的参数其值会从SecurityContext的上下文读取相应的Authentication校验信息
2. 有一个要求，被该注解修饰的参数须同SecurityContext的上下文存放的Authentication信息为同一接口，否则则会返回null。如果设置了errorOnInvalidType属性为true，则会抛异常
3. 综上所述，该注解主要是方便将校验通过的Token用于参数赋值，其它的作用也不是很大

@EnableGlobalAuthentication

再来分析下springboot-security的公共认证校验是什么概念，贴下源码

@Retention(value = java.lang.annotation.RetentionPolicy.RUNTIME)
@Target(value = { java.lang.annotation.ElementType.TYPE })
@Documented
@Import(AuthenticationConfiguration.class)
@Configuration
public @interface EnableGlobalAuthentication {
}

OK，直接进入相应的AuthenticationConfiguration类进行具体的分析

1.其引入了ObjectPostProcessorConfiguration配置用于创建AutowireBeanFactoryObjectPostProcessor类，作用应该是通过Spring上下文实例相应的实体类并注册到bean工厂中

    @Beanpublic ObjectPostProcessor<Object> objectPostProcessor(AutowireCapableBeanFactory beanFactory) {return new AutowireBeanFactoryObjectPostProcessor(beanFactory);}

2.创建基于密码机制的认证管理器Bean，类型为DefaultPasswordEncoderAuthenticationManagerBuilder

    @Beanpublic AuthenticationManagerBuilder authenticationManagerBuilder(ObjectPostProcessor<Object> objectPostProcessor, ApplicationContext context) {// 密码加密器LazyPasswordEncoder defaultPasswordEncoder = new LazyPasswordEncoder(context);// 认证事件传播器AuthenticationEventPublisher authenticationEventPublisher = getBeanOrNull(context, AuthenticationEventPublisher.class);// 默认的认证管理器DefaultPasswordEncoderAuthenticationManagerBuilder result = new DefaultPasswordEncoderAuthenticationManagerBuilder(objectPostProcessor, defaultPasswordEncoder);if (authenticationEventPublisher != null) {result.authenticationEventPublisher(authenticationEventPublisher);}return result;}

上述的密码加密器支持多种方式的加密，比如bcrypt(默认)/ladp/md5/sha-1等，感兴趣的读者可自行阅读。用户也可多用此Bean作额外的扩展，例如官方建议的如下代码

@Configuration
@EnableGlobalAuthentication
public class MyGlobalAuthenticationConfiguration {@Autowiredpublic void configureGlobal(AuthenticationManagerBuilder auth) {auth.inMemoryAuthentication().withUser("user").password("password").roles("USER").and().withUser("admin").password("password").roles("ADMIN,USER");}}

3.创建基于UserDetails的认证器，用于管理用户的授权信息

    @Beanpublic static InitializeUserDetailsBeanManagerConfigurer initializeUserDetailsBeanManagerConfigurer(ApplicationContext context) {return new InitializeUserDetailsBeanManagerConfigurer(context);}

其会创建基于Datasource源的DaoAuthenticationProvider认证校验器，前提是ApplicationContext上下文存在UserDetailsServiceBean对象，否则会不创建。如果用户想基于数据库或者其他数据源的可尝试复写UserDetailsService接口

@Configuration
public class DaoUserDetailsServiceConfig {/*** load user info by dao** @see org.springframework.security.authentication.dao.DaoAuthenticationProvider*/@Configurationpublic static class DefaultUserDetailsService implements UserDetailsService {private static final String DEFAULT_PASS = "defaultPass";// admin authorityprivate Collection<? extends GrantedAuthority> adminAuthority;@Resourceprivate PasswordEncoder defaultPasswordEncoder;public DefaultUserDetailsService() {SimpleGrantedAuthority authority = new SimpleGrantedAuthority("ROLE_ADMIN");List<GrantedAuthority> authorities = new ArrayList<>();authorities.add(authority);adminAuthority = Collections.unmodifiableList(authorities);}@Overridepublic UserDetails loadUserByUsername(String username) throws UsernameNotFoundException {User userdetails = new User(username, defaultPasswordEncoder.encode(DEFAULT_PASS), adminAuthority);return userdetails;}@Beanpublic PasswordEncoder daoPasswordEncoder() {PasswordEncoder passwordEncoder = new BCryptPasswordEncoder();return passwordEncoder;}}
}

注意：实现UserDetailsService的自定义实例请确保只有一个注册至ApplicationContext上，否则上述的基于数据源配置无法自动化配置；但也可通过AuthenticationManagerBuilder#userDetailsService()方法来进行相应的配置

4.创建AuthenticationProvider认证器，用于用户信息的校验

    @Beanpublic static InitializeAuthenticationProviderBeanManagerConfigurer initializeAuthenticationProviderBeanManagerConfigurer(ApplicationContext context) {return new InitializeAuthenticationProviderBeanManagerConfigurer(context);}

同第三点，只是它就配置简单的AuthenticationProvider至相应的AuthenticationManagerBuilderBean中

所以综上所述，@EnableGlobalAuthentication注解的主要目的是配置认证管理器，里面包含了加密器以及相应的认证器

WebSecurityConfiguration

web方面的安全配置，笔者也根据加载的顺序来进行分析

1.获取WebSecurityConfigurer接口bean集合的AutowiredWebSecurityConfigurersIgnoreParents类

    @Beanpublic static AutowiredWebSecurityConfigurersIgnoreParents autowiredWebSecurityConfigurersIgnoreParents(ConfigurableListableBeanFactory beanFactory) {return new AutowiredWebSecurityConfigurersIgnoreParents(beanFactory);}

此Bean用于获取所有注册在bean工厂上的WebSecurityConfigurer接口，用户也一般通过此接口的抽象类WebSecurityConfigurerAdapter来进行相应的扩展

2.设置Security的Filter过滤链配置，提前为创建过滤链作准备

    @Autowired(required = false)public void setFilterChainProxySecurityConfigurer(ObjectPostProcessor<Object> objectPostProcessor,@Value("#{@autowiredWebSecurityConfigurersIgnoreParents.getWebSecurityConfigurers()}") List<SecurityConfigurer<Filter, WebSecurity>> webSecurityConfigurers)throws Exception {// WebSecurity创建webSecurity = objectPostProcessor.postProcess(new WebSecurity(objectPostProcessor));if (debugEnabled != null) {webSecurity.debug(debugEnabled);}// 根据@Order属性排序Collections.sort(webSecurityConfigurers, AnnotationAwareOrderComparator.INSTANCE);Integer previousOrder = null;Object previousConfig = null;// 校验Order对应的值，不允许相同，否则会抛出异常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;}// 对排序过的SecurityConfigurer依次放入WebSecurity对象中for (SecurityConfigurer<Filter, WebSecurity> webSecurityConfigurer : webSecurityConfigurers) {webSecurity.apply(webSecurityConfigurer);}this.webSecurityConfigurers = webSecurityConfigurers;}

这里便提一下，我们在继承WebSecurityConfigurerAdapter抽象类的时候，记得在其头上加上@Order属性，并且保证值唯一

3.创建Security过滤链

    @Bean(name = AbstractSecurityWebApplicationInitializer.DEFAULT_FILTER_NAME)public Filter springSecurityFilterChain() throws Exception {// 如果用户没有配置WebSecurityConfigurer接口，则创建一个空的boolean hasConfigurers = webSecurityConfigurers != null&& !webSecurityConfigurers.isEmpty();if (!hasConfigurers) {WebSecurityConfigurerAdapter adapter = objectObjectPostProcessor.postProcess(new WebSecurityConfigurerAdapter() {});webSecurity.apply(adapter);}// create Filterreturn webSecurity.build();}

看来Filter拦截器的配置是通过WebSecurity这个类来完成的，限于里面的代码过于复杂，本文就不展开了，感兴趣的读者可以重点关注下此类。由此可以得出Springboot的安全校验是通过过滤链的设计方式来完成的

4.URI权限校验Bean，其依赖于第三点的配置

    @Bean@DependsOn(AbstractSecurityWebApplicationInitializer.DEFAULT_FILTER_NAME)public WebInvocationPrivilegeEvaluator privilegeEvaluator() throws Exception {return webSecurity.getPrivilegeEvaluator();}

5.安全校验表达式验证Bean，其也依赖于第三点的配置，应该是与第四点搭配使用

    @Bean@DependsOn(AbstractSecurityWebApplicationInitializer.DEFAULT_FILTER_NAME)public SecurityExpressionHandler<FilterInvocation> webSecurityExpressionHandler() {return webSecurity.getExpressionHandler();}

小结

Springboot整合的Security板块内容很多，本文也展示不完，不过值得关注的是以下几个方面
1)WebSecurity的个性化配置类，一般是复写抽象接口WebSecurityConfigurerAdapter，再加上@EnableWebSecurity注解便可

2)AuthenticationManagerBuilder认证校验器，重点关注其中的密码校验器，用于密码的加密解密，默认使用bcrypt方式。如果用户想通过其他数据源获取用户信息，可以关注UserDetailsService接口。推荐用户均使用AuthenticationManagerBuilder类配置认证机制！

3)WebSecurity类，此类是Springboot Security模块的核心类，具体的过滤链配置均是由此类得到的。读者以及笔者应该对此加以关注