Spring Security是一个能够为基于Spring的企业应用系统提供声明式的安全访问控制解决方案的安全框架。它提供了一组可以在Spring应用上下文中配置的Bean,充分利用了Spring IoC,DI(控制反转Inversion of Control ,DI:Dependency Injection 依赖注入)和AOP(面向切面编程)功能,为应用系统提供声明式的安全访问控制功能,减少了为企业系统安全控制编写大量重复代码的工作。
为了方便理解Spring Security认证流程,特意画了如下的类图,包含相关的核心认证类
核心验证器
该对象提供了认证方法的入口,接收一个 Authentiaton
对象作为参数;
public interface AuthenticationManager { Authentication authenticate(Authentication authentication) throws AuthenticationException; }
它是 AuthenticationManager
的一个实现类,提供了基本的认证逻辑和方法;它包含了一个 List<AuthenticationProvider>
对象,通过 AuthenticationProvider 接口来扩展出不同的认证提供者(当 Spring Security
默认提供的实现类不能满足需求的时候可以扩展 AuthenticationProvider
覆盖 supports(Class<?> authentication)
方法);
AuthenticationManager
接收 Authentication
对象作为参数,并通过 authenticate(Authentication)
方法对其进行验证; AuthenticationProvider
实现类用来支撑对 Authentication
对象的验证动作; UsernamePasswordAuthenticationToken
实现了 Authentication
主要是将用户输入的用户名和密码进行封装,并供给 AuthenticationManager
进行验证;验证完成以后将返回一个认证成功的 Authentication
对象;
Authentication
对象中的主要方法
public interface Authentication extends Principal, Serializable { //#1.权限结合,可使用AuthorityUtils.commaSeparatedStringToAuthorityList("admin,ROLE_ADMIN")返回字符串权限集合 Collection<? extends GrantedAuthority> getAuthorities(); //#2.用户名密码认证时可以理解为密码 Object getCredentials(); //#3.认证时包含的一些信息。 Object getDetails(); //#4.用户名密码认证时可理解时用户名 Object getPrincipal(); #5.是否被认证,认证为true boolean isAuthenticated(); #6.设置是否能被认证 void setAuthenticated(boolean isAuthenticated) throws IllegalArgumentException;
ProviderManager
是 AuthenticationManager
的实现类,提供了基本认证实现逻辑和流程;
public Authentication authenticate(Authentication authentication) throws AuthenticationException { //#1.获取当前的Authentication的认证类型 Class<? extends Authentication> toTest = authentication.getClass(); AuthenticationException lastException = null; Authentication result = null; boolean debug = logger.isDebugEnabled(); //#2.遍历所有的providers使用supports方法判断该provider是否支持当前的认证类型,不支持的话继续遍历 for (AuthenticationProvider provider : getProviders()) { if (!provider.supports(toTest)) { continue; } if (debug) { logger.debug("Authentication attempt using " + provider.getClass().getName()); } try { #3.支持的话调用provider的authenticat方法认证 result = provider.authenticate(authentication); if (result != null) { #4.认证通过的话重新生成Authentication对应的Token copyDetails(authentication, result); break; } } catch (AccountStatusException e) { prepareException(e, authentication); // SEC-546: Avoid polling additional providers if auth failure is due to // invalid account status throw e; } catch (InternalAuthenticationServiceException e) { prepareException(e, authentication); throw e; } catch (AuthenticationException e) { lastException = e; } } if (result == null && parent != null) { // Allow the parent to try. try { #5.如果#1 没有验证通过,则使用父类型AuthenticationManager进行验证 result = parent.authenticate(authentication); } catch (ProviderNotFoundException e) { // ignore as we will throw below if no other exception occurred prior to // calling parent and the parent // may throw ProviderNotFound even though a provider in the child already // handled the request } catch (AuthenticationException e) { lastException = e; } } #6. 是否擦出敏感信息 if (result != null) { if (eraseCredentialsAfterAuthentication && (result instanceof CredentialsContainer)) { // Authentication is complete. Remove credentials and other secret data // from authentication ((CredentialsContainer) result).eraseCredentials(); } eventPublisher.publishAuthenticationSuccess(result); return result; } // Parent was null, or didn't authenticate (or throw an exception). if (lastException == null) { lastException = new ProviderNotFoundException(messages.getMessage( "ProviderManager.providerNotFound", new Object[] { toTest.getName() }, "No AuthenticationProvider found for {0}")); } prepareException(lastException, authentication); throw lastException; }
ProviderManager
通过 AuthenticationProvider
扩展出更多的验证提供的方式;而 AuthenticationProvider
本身也就是一个接口,从类图中我们可以看出它的实现类 AbstractUserDetailsAuthenticationProvider
和 AbstractUserDetailsAuthenticationProvider
的子类 DaoAuthenticationProvider
。 DaoAuthenticationProvider
是 Spring Security
中一个核心的 Provider
,对所有的数据库提供了基本方法和入口。
DaoAuthenticationProvider
主要做了以下事情
#1.可直接返回BCryptPasswordEncoder,也可以自己实现该接口使用自己的加密算法核心方法String encode(CharSequence rawPassword);和boolean matches(CharSequence rawPassword, String encodedPassword);
private PasswordEncoder passwordEncoder;
2. 实现了 `AbstractUserDetailsAuthenticationProvider` 两个抽象方法, 1. 获取用户信息的扩展点 ```java protected final UserDetails retrieveUser(String username, UsernamePasswordAuthenticationToken authentication) throws AuthenticationException { UserDetails loadedUser; try { loadedUser = this.getUserDetailsService().loadUserByUsername(username); }
主要是通过注入`UserDetailsService`接口对象,并调用其接口方法 `loadUserByUsername(String username)` 获取得到相关的用户信息。`UserDetailsService`接口非常重要。 2. 实现 additionalAuthenticationChecks 的验证方法(主要验证密码);
AbstractUserDetailsAuthenticationProvider
为 DaoAuthenticationProvider
提供了基本的认证方法;
public Authentication authenticate(Authentication authentication) throws AuthenticationException { Assert.isInstanceOf(UsernamePasswordAuthenticationToken.class, authentication, messages.getMessage( "AbstractUserDetailsAuthenticationProvider.onlySupports", "Only UsernamePasswordAuthenticationToken is supported")); // Determine username String username = (authentication.getPrincipal() == null) ? "NONE_PROVIDED" : authentication.getName(); boolean cacheWasUsed = true; UserDetails user = this.userCache.getUserFromCache(username); if (user == null) { cacheWasUsed = false; try { #1.获取用户信息由子类实现即DaoAuthenticationProvider user = retrieveUser(username, (UsernamePasswordAuthenticationToken) authentication); } catch (UsernameNotFoundException notFound) { logger.debug("User '" + username + "' not found"); if (hideUserNotFoundExceptions) { throw new BadCredentialsException(messages.getMessage( "AbstractUserDetailsAuthenticationProvider.badCredentials", "Bad credentials")); } else { throw notFound; } } Assert.notNull(user, "retrieveUser returned null - a violation of the interface contract"); } try { #2.前检查由DefaultPreAuthenticationChecks类实现(主要判断当前用户是否锁定,过期,冻结User接口) preAuthenticationChecks.check(user); #3.子类实现 additionalAuthenticationChecks(user, (UsernamePasswordAuthenticationToken) authentication); } catch (AuthenticationException exception) { if (cacheWasUsed) { // There was a problem, so try again after checking // we're using latest data (i.e. not from the cache) cacheWasUsed = false; user = retrieveUser(username, (UsernamePasswordAuthenticationToken) authentication); preAuthenticationChecks.check(user); additionalAuthenticationChecks(user, (UsernamePasswordAuthenticationToken) authentication); } else { throw exception; } } #4.检测用户密码是否过期对应#2 的User接口 postAuthenticationChecks.check(user); if (!cacheWasUsed) { this.userCache.putUserInCache(user); } Object principalToReturn = user; if (forcePrincipalAsString) { principalToReturn = user.getUsername(); } return createSuccessAuthentication(principalToReturn, authentication, user); }
AbstractUserDetailsAuthenticationProvider
主要实现了 AuthenticationProvider
的接口方法 authenticate
并提供了相关的验证逻辑;
UserDetails
AbstractUserDetailsAuthenticationProvider
定义了一个抽象的方法 protected abstract UserDetails retrieveUser(String username, UsernamePasswordAuthenticationToken authentication) throws AuthenticationException;
2. 三步验证工作 1. preAuthenticationChecks 2. additionalAuthenticationChecks(抽象方法,子类实现) 3. postAuthenticationChecks 3. 将已通过验证的用户信息封装成 UsernamePasswordAuthenticationToken 对象并返回;该对象封装了用户的身份信息,以及相应的权限信息,相关源码如下, ```java protected Authentication createSuccessAuthentication(Object principal, UsernamePasswordAuthenticationToken result = new UsernamePasswordAuthenticationToken( principal, authentication.getCredentials(), authoritiesMapper.mapAuthorities(user.getAuthorities())); result.setDetails(authentication.getDetails()); return result; }
UserDetailsService
是一个接口,提供了一个方法
public interface UserDetailsService { UserDetails loadUserByUsername(String username) throws UsernameNotFoundException; }
通过用户名 username 调用方法 loadUserByUsername 返回了一个UserDetails接口对象(对应 AbstractUserDetailsAuthenticationProvider
的三步验证方法);
public interface UserDetails extends Serializable { #1.权限集合 Collection<? extends GrantedAuthority> getAuthorities(); #2.密码 String getPassword(); #3.用户民 String getUsername(); #4.用户是否过期 boolean isAccountNonExpired(); #5.是否锁定 boolean isAccountNonLocked(); #6.用户密码是否过期 boolean isCredentialsNonExpired(); #7.账号是否可用(可理解为是否删除) boolean isEnabled(); }
Spring 为 UserDetailsService
默认提供了一个实现类 org.springframework.security.core.userdetails.jdbc. JdbcDaoImpl
该实现类主要是提供基于 JDBC
对 User 进行增、删、查、改的方法
public class JdbcUserDetailsManager extends JdbcDaoImpl implements UserDetailsManager, GroupManager { // ~ Static fields/initializers // ===================================================================================== // UserDetailsManager SQL #1.定义了一些列对数据库操作的语句 public static final String DEF_CREATE_USER_SQL = "insert into users (username, password, enabled) values (?,?,?)"; public static final String DEF_DELETE_USER_SQL = "delete from users where username = ?"; public static final String DEF_UPDATE_USER_SQL = "update users set password = ?, enabled = ? where username = ?"; public static final String DEF_INSERT_AUTHORITY_SQL = "insert into authorities (username, authority) values (?,?)"; public static final String DEF_DELETE_USER_AUTHORITIES_SQL = "delete from authorities where username = ?"; public static final String DEF_USER_EXISTS_SQL = "select username from users where username = ?"; public static final String DEF_CHANGE_PASSWORD_SQL = "update users set password = ? where username = ?";
该实现类主要是提供基于 内存
对 User 进行增、删、查、改的方法 `public class InMemoryUserDetailsManager implements UserDetailsManager { protected final Log logger = LogFactory.getLog(getClass()); #1.用MAP 存储 private final Map<String, MutableUserDetails> users = new HashMap<String, MutableUserDetails>();
private AuthenticationManager authenticationManager; public InMemoryUserDetailsManager() { } public InMemoryUserDetailsManager(Collection<UserDetails> users) { for (UserDetails user : users) { createUser(user); } }`
UserDetailsService
接口作为桥梁,是 DaoAuthenticationProvier
与特定用户信息来源进行解耦的地方, UserDetailsService
由 UserDetails
和 UserDetailsManage
r所构成; UserDetails
和 UserDetailsManager
各司其责,一个是对基本用户信息进行封装,一个是对基本用户信息进行管理;
特别注意
, UserDetailsService
、 UserDetails
以及 UserDetailsManager
都是可被用户自定义的扩展点,我们可以继承这些接口提供自己的读取用户来源和管理用户的方法,比如我们可以自己实现一个 与特定 ORM 框架,比如 Mybatis 或者 Hibernate,相关的 UserDetailsService
和 UserDetailsManager
;