SpringSecurity 源码分析一

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spring

通过SecurityContextHolder.getContext()获得SecurityContext
总接口SecurityContextHolderStrategy

private static void initialize() {
        if ((strategyName == null) || "".equals(strategyName)) {
            // Set default
            strategyName = MODE_THREADLOCAL;
        }

        if (strategyName.equals(MODE_THREADLOCAL)) {
            strategy = new ThreadLocalSecurityContextHolderStrategy();
        } else if (strategyName.equals(MODE_INHERITABLETHREADLOCAL)) {
            strategy = new InheritableThreadLocalSecurityContextHolderStrategy();
        } else if (strategyName.equals(MODE_GLOBAL)) {
            strategy = new GlobalSecurityContextHolderStrategy();
        } else {
            // Try to load a custom strategy
            try {
                Class clazz = Class.forName(strategyName);
                Constructor customStrategy = clazz.getConstructor(new Class[] {});
                strategy = (SecurityContextHolderStrategy) customStrategy.newInstance(new Object[] {});
            } catch (Exception ex) {
                ReflectionUtils.handleReflectionException(ex);
            }
        }

initializeCount++;
}

当SecurityContextHolder初始化的时候。判断调用哪个SecurityContextHolderStrategy的实现类

Authentication auth = SecurityContextHolder.getContext().getAuthentication();

让后通过 SecurityContext 接口实现类 SecurityContextImpl 获得 getAuthentication()的到Authentication 对象，Authentication 对象中装了很多用户信息

Authentication 主要是包括一些用户认证的信息，比如权限啊。名字啊什么的。。。

Springsecurity 主要是认证+授权+filter

认证分证管理器+认证者。

认证管理器(org.springframework.security.AuthenticationManager接口

public class ProviderManager extends AbstractAuthenticationManager implements InitializingBean, MessageSourceAware,
        ApplicationEventPublisherAware  {
    //~ Static fields/initializers =====================================================================================

    private static final Log logger = LogFactory.getLog(ProviderManager.class);
    private static final Properties DEFAULT_EXCEPTION_MAPPINGS = new Properties();

    //~ Instance fields ================================================================================================

    private ApplicationEventPublisher applicationEventPublisher;
    private ConcurrentSessionController sessionController = new NullConcurrentSessionController();
    private List providers;
    protected MessageSourceAccessor messages = SpringSecurityMessageSource.getAccessor();
    private Properties exceptionMappings = new Properties();
    private Properties additionalExceptionMappings = new Properties();
 	<!-- 
	           认证管理器(org.springframework.security.AuthenticationManager接口) 
		 org.springframework.security.providers.ProviderManager是认证管理器的一个实现,
		 ProviderManager通过遍历一个提供者的集合来实现身份验证,
		 直到某一个认证提供者能够成功地验证该用户的身份
	-->
	<!--
         通过Providers提供认证者列表,如果一个认证提供者失败可以尝试另外一个认证提供者,以保证获取不同来源的身份认证，如
         DaoAuthenticationProvider        从数据库中读取用户信息验证身份
         AnonymousAuthenticationProvider  匿名用户身份认证
         RememberMeAuthenticationProvider 已存cookie中的用户信息身份认证

         其它的还有
         AuthByAdapterProvider           使用容器的适配器验证身份
         CasAuthenticationProvider       根据Yale中心认证服务验证身份, 用于实现单点登陆
         JaasAuthenticationProvider      从JASS登陆配置中获取用户信息验证身份
         RemoteAuthenticationProvider    根据远程服务验证用户身份
         RunAsImplAuthenticationProvider 对身份已被管理器替换的用户进行验证
         X509AuthenticationProvider      从X509认证中获取用户信息验证身份
         TestingAuthenticationProvider   单元测试时使用

         每个认证者会对自己指定的证明信息进行认证，如DaoAuthenticationProvider仅对UsernamePasswordAuthenticationToken这个证明信息进行认证。
       总接口 AuthenticationManager 管理器 装着 很多个AuthenticationProvider 管理者-->	
	<bean id="authenticationManager" 
		class="org.springframework.security.providers.ProviderManager"
		p:sessionController-ref="concurrentSessionController">
		<!--   private List providers;<装着很多个认证器> -->
		<property name="providers">
			<list>
				<ref bean="daoAuthenticationProvider"/>
				<bean 
					class="org.springframework.security.providers.anonymous.AnonymousAuthenticationProvider"
					p:key="springsecurity"/>
				<bean 
					class="org.springframework.security.providers.rememberme.RememberMeAuthenticationProvider"
					p:key="springsecurity"/>
			</list>
		</property>	
	</bean>

可以看出一个认证器里面包含了多个认证者

下面来看看认证者接口

public interface AuthenticationProvider {
    //~ Methods ========================================================================================================

    /**
     * Performs authentication with the same contract as {@link
     * org.springframework.security.AuthenticationManager#authenticate(Authentication)}.
     *
     * @param authentication the authentication request object.
     *
     * @return a fully authenticated object including credentials. May return <code>null</code> if the
     *         <code>AuthenticationProvider</code> is unable to support authentication of the passed
     *         <code>Authentication</code> object. In such a case, the next <code>AuthenticationProvider</code> that
     *         supports the presented <code>Authentication</code> class will be tried.
     *
     * @throws AuthenticationException if authentication fails.
     */
    Authentication authenticate(Authentication authentication)
        throws AuthenticationException;

有一个认证方法。不同的实现类通过这个方法来认证用户。下面来看下DaoAuthenticationProvider认证者是怎么认证用户的。

public class DaoAuthenticationProvider extends AbstractUserDetailsAuthenticationProvider {

    //~ Instance fields ================================================================================================

    private PasswordEncoder passwordEncoder = new PlaintextPasswordEncoder();

    private SaltSource saltSource;

    private UserDetailsService userDetailsService;

    private boolean includeDetailsObject = true;


 protected final UserDetails retrieveUser(String username, UsernamePasswordAuthenticationToken authentication)
            throws AuthenticationException {
        UserDetails loadedUser;

        try {
            loadedUser = this.getUserDetailsService().loadUserByUsername(username);
        }
        catch (DataAccessException repositoryProblem) {
            throw new AuthenticationServiceException(repositoryProblem.getMessage(), repositoryProblem);
        }

        if (loadedUser == null) {
            throw new AuthenticationServiceException(
                    "UserDetailsService returned null, which is an interface contract violation");
        }
        return loadedUser;
    }

DaoAuthenticationProvider认证者通过注入UserDetailsService来获取用户信息

<!-- 认证管理器  总接口AuthenticationProvider -->
	<bean id="daoAuthenticationProvider" 
		class="org.springframework.security.providers.dao.DaoAuthenticationProvider"
		p:passwordEncoder-ref="passwordEncoder"
		p:userDetailsService-ref="userDetailsService"/>

UserDetailsService 就相当于我们的业务逻辑层通过不同的方式获取用户信息比如：

<!-- 获得userDetails的service  总接口UserDetailsService 子类-->
	 <bean id="userDetailsService" 
	 	class="org.springframework.security.userdetails.memory.InMemoryDaoImpl">
	 	<property name="userProperties">
	 		<bean class="org.springframework.beans.factory.config.PropertiesFactoryBean"
	 			p:location="/WEB-INF/users.properties"/>
	 	</property>

通过properties文件来配置用户权限

admin=admin,ROLE_SUPERVISOR
user1=user1,ROLE_USER
user2=user2,ROLE_USER
user3=user3,disabled,ROLE_USER
#scott/wombat
scott=2b58af6dddbd072ed27ffc86725d7d3a,ROLE_USER

还可以这样：

<property name="userMap">
	 		<value>
	 			admin=admin,ROLE_SUPERVISOR
				user1=user1,ROLE_USER
				user2=user2,ROLE_USER
				user3=user3,disabled,ROLE_USER
	 		</value>
	 	</property>

至于org.springframework.security.userdetails.memory.InMemoryDaoImpl 怎么封装，可想而知

 */
public class InMemoryDaoImpl implements UserDetailsService, InitializingBean {

    public void afterPropertiesSet() throws Exception {
        Assert.notNull(this.userMap,
            "A list of users, passwords, enabled/disabled status and their granted authorities must be set");
    }

    public UserMap getUserMap() {
        return userMap;
    }
    public UserDetails loadUserByUsername(String username)
        throws UsernameNotFoundException, DataAccessException {
        return userMap.getUser(username);
    }

    public void setUserMap(UserMap userMap) {
        this.userMap = userMap;
    }
    public void setUserProperties(Properties props) {
        UserMap userMap = new UserMap();
        this.userMap = UserMapEditor.addUsersFromProperties(userMap, props);
    }
}

下面来看这个service有多少中实现方式。实现类

看实现类名字就可以想到。可以通过jdbc配置在数据库中，InMemoryDaoImpl配置文件中（加载到内存）

可以把用户信息放到Ldap。 UserDetailsService 通过loadUserByUsername方法加载用户信息

class CachingUserDetailsService implements UserDetailsService {
	private UserCache userCache = new NullUserCache();
	private UserDetailsService delegate;

	CachingUserDetailsService(UserDetailsService delegate) {
		this.delegate = delegate;
	}

	public UserCache getUserCache() {
		return userCache;
	}

	public void setUserCache(UserCache userCache) {
		this.userCache = userCache;
	}

	public UserDetails loadUserByUsername(String username) {
		UserDetails user = userCache.getUserFromCache(username);
		
		if (user == null) {
			user = delegate.loadUserByUsername(username);
		}
		
		Assert.notNull(user, "UserDetailsService " + delegate + " returned null for username " + username + ". " +
				"This is an interface contract violation");
		
		userCache.putUserInCache(user);
		
		return user;
	}
}

还可以为实现类注入缓存默认是private UserCache userCache = new NullUserCache();

下面来看下springsecurity的缓存

springsecurity的缓存主要还是通过ehcache缓存实现的。只是封装了一下方法。下面请看UserCache实现类

public class EhCacheBasedUserCache implements UserCache, InitializingBean {
    //~ Static fields/initializers =====================================================================================

    private static final Log logger = LogFactory.getLog(EhCacheBasedUserCache.class);

    //~ Instance fields ================================================================================================

    private Ehcache cache;

    //~ Methods ========================================================================================================

    public void afterPropertiesSet() throws Exception {
        Assert.notNull(cache, "cache mandatory");
    }

    public Ehcache getCache() {
        return cache;
    }

    public UserDetails getUserFromCache(String username) {
        Element element = null;

        try {
            element = cache.get(username);
        } catch (CacheException cacheException) {
            throw new DataRetrievalFailureException("Cache failure: " + cacheException.getMessage());
        }

        if (logger.isDebugEnabled()) {
            logger.debug("Cache hit: " + (element != null) + "; username: " + username);
        }

        if (element == null) {
            return null;
        } else {
            return (UserDetails) element.getValue();
        }
    }

    public void putUserInCache(UserDetails user) {
        Element element = new Element(user.getUsername(), user);

        if (logger.isDebugEnabled()) {
            logger.debug("Cache put: " + element.getKey());
        }

        cache.put(element);
    }

    public void removeUserFromCache(UserDetails user) {
        if (logger.isDebugEnabled()) {
            logger.debug("Cache remove: " + user.getUsername());
        }

        this.removeUserFromCache(user.getUsername());
    }

    public void removeUserFromCache(String username) {
        cache.remove(username);
    }

    public void setCache(Ehcache cache) {
        this.cache = cache;
    }
}

在这里可以看到这些方法都是调用了ehcache里面的方法。这里的 private Ehcache cache;是靠你在配置文件配的。注入进来的。

<bean class="org.springframework.security.providers.dao.cache.EhCacheBasedUserCache">
	  <property name="userCache" value="userCahce"></property>
	 </bean>

SpringSecurity刚入门不久，主要把概率，理论弄清楚了。感觉还是比较容易的。让后在结合源码看一下。映像就深刻多了，今天就写到这了。下次在看下SpringSecurity的Filter在说吧。。。。。