springboot情操陶冶-web配置(八)

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

    @Bean
    public 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

    @Bean
    public 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 {

    @Autowired
    public 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

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

其会创建基于Datasource源的DaoAuthenticationProvider权限校验器，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
     */
    @Configuration
    public static class DefaultUserDetailsService implements UserDetailsService {

        private static final String DEFAULT_PASS = "defaultPass";

        // admin authority
        private Collection<? extends GrantedAuthority> adminAuthority;

        @Resource
        private PasswordEncoder defaultPasswordEncoder;

        public DefaultUserDetailsService() {
            SimpleGrantedAuthority authority = new SimpleGrantedAuthority("ROLE_ADMIN");
            List<GrantedAuthority> authorities = new ArrayList<>();
            authorities.add(authority);

            adminAuthority = Collections.unmodifiableList(authorities);
        }

        @Override
        public UserDetails loadUserByUsername(String username) throws UsernameNotFoundException {
            User userdetails = new User(username, defaultPasswordEncoder.encode(DEFAULT_PASS), adminAuthority);

            return userdetails;
        }

        @Bean
        public PasswordEncoder daoPasswordEncoder() {
            PasswordEncoder passwordEncoder = new BCryptPasswordEncoder();

            return passwordEncoder;
        }
    }
}

---

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

    @Bean
    public 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

    @Bean
    public 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 Filter
        return 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

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