基于java config的springSecurity(五)--session并发控制

参考资料:spring-security-reference.pdf的Session Management.特别是Concurrency Control小节.
管理session可以做到:
a.跟踪活跃的session,统计在线人数,显示在线用户.
b.控制并发,即一个用户最多可以使用多少个session登录,比如设为1,结果就为,同一个时间里,第二处登录要么不能登录,要么使前一个登录失效.

1.注册自定义的SessionRegistry(通过它可以做到上面的a点)

@Bean  

public SessionRegistry sessionRegistry(){  
    return new SessionRegistryImpl();  
}  

2.使用session并发管理,并注入上面自定义的SessionRegistry

@Override  

protected void configure(HttpSecurity http) throws Exception {  
    http.authorizeRequests().anyRequest().authenticated()  
        .and().formLogin().loginPage("/login").failureUrl("/login?error").usernameParameter("username").passwordParameter("password").permitAll()  
        .and().logout().logoutUrl("/logout").logoutSuccessUrl("/login?logout").permitAll()  
        .and().rememberMe().key("9D119EE5A2B7DAF6B4DC1EF871D0AC3C")  
        .and().exceptionHandling().accessDeniedPage("/exception/403")  
        .and().sessionManagement().maximumSessions(2).expiredUrl("/login?expired").sessionRegistry(sessionRegistry());  
}  

3.监听session创建和销毁的HttpSessionListener.让spring security更新有关会话的生命周期,实现上创建的监听只使用销毁事件,至于session创建,security是调用org.springframework.security.core.session.SessionRegistry#registerNewSession
针对servlet管理的session,应使用org.springframework.security.web.session.HttpSessionEventPublisher,方法有多种:
a.重写org.springframework.security.web.context.AbstractSecurityWebApplicationInitializer#enableHttpSessionEventPublisher

public class SecurityWebApplicationInitializer extends AbstractSecurityWebApplicationInitializer {
    @Override
    protected boolean enableHttpSessionEventPublisher() {
        return true;
    }
}

b.在AbstractAnnotationConfigDispatcherServletInitializer的子类DispatcherServletInitializer添加

@Override  
public void onStartup(ServletContext servletContext) throws ServletException {  
    super.onStartup(servletContext);  
    FilterRegistration.Dynamic encodingFilter = servletContext.addFilter("encoding-filter", CharacterEncodingFilter.class);  
    encodingFilter.setInitParameter("encoding", "UTF-8");  
    encodingFilter.setInitParameter("forceEncoding", "true");  
    encodingFilter.setAsyncSupported(true);  
    encodingFilter.addMappingForUrlPatterns(null, false, "/*");  
    servletContext.addListener(new HttpSessionEventPublisher());  
} 

使用springSession,直接向servletContext添加的session销毁监听是没用的,看springSession的文档http://docs.spring.io/spring-session/docs/current/reference/html5/#httpsession-httpsessionlistener,将org.springframework.security.web.session.HttpSessionEventPublisher注册成Bean就可以了.它的底层是对springSession的创建和销毁进行监听,不一样的.
还要注意的是,添加对HttpSessionListener的支持是从spring Session 1.1.0开始的,写这博文的时候,这版本还没出来.所以,以前的源码有问题.

@Configuration
@EnableRedisHttpSession
@PropertySource("classpath:config.properties")
public class HttpSessionConfig {
    @Resource
    private Environment env;
    @Bean
    public JedisConnectionFactory jedisConnectionFactory() {
        JedisConnectionFactory connectionFactory = new JedisConnectionFactory();
        connectionFactory.setHostName(env.getProperty("redis.host"));
        connectionFactory.setPort(env.getProperty("redis.port",Integer.class));
        return connectionFactory;
    }
    @Bean
    public HttpSessionEventPublisher httpSessionEventPublisher() {
        return new HttpSessionEventPublisher();
    }
}

4.在spring controller注入SessionRegistry,测试.

附加session的创建与销毁分析:
至于session的创建比较简单,认证成功后,security直接调用

org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter#doFilter{
    sessionStrategy.onAuthentication(authResult, request, response);
}
org.springframework.security.web.authentication.session.RegisterSessionAuthenticationStrategy#onAuthentication{
    sessionRegistry.registerNewSession(request.getSession().getId(), uthentication.getPrincipal());
}

session的销毁.没有特殊修改,org.springframework.security.web.authentication.logout.LogoutFilter#handlers只有一个元素org.springframework.security.web.authentication.logout.SecurityContextLogoutHandler,如果主动logout,就会触发org.springframework.security.web.authentication.logout.LogoutFilter#doFilter,进而调用org.springframework.security.web.authentication.logout.SecurityContextLogoutHandler#logout,从这个方法可以看出别人是怎么处理失效的session的

public void logout(HttpServletRequest request, HttpServletResponse response,
        Authentication authentication) {
    Assert.notNull(request, "HttpServletRequest required");
    if (invalidateHttpSession) {
        HttpSession session = request.getSession(false);
        if (session != null) {
            logger.debug("Invalidating session: " + session.getId());
            session.invalidate();
        }
    }

    if (clearAuthentication) {
        SecurityContext context = SecurityContextHolder.getContext();
        context.setAuthentication(null);
    }

    SecurityContextHolder.clearContext();
}

这里可以看到使session失效,调用SecurityContextHolder.getContext().setAuthentication(null),清理SecurityContext
spring security登出操作和session过期都会引起session被销毁.就会触发org.springframework.security.web.session.HttpSessionEventPublisher#sessionDestroyed事件.源码如下

public void sessionDestroyed(HttpSessionEvent event) {
    HttpSessionDestroyedEvent e = new HttpSessionDestroyedEvent(event.getSession());
    Log log = LogFactory.getLog(LOGGER_NAME);
    if (log.isDebugEnabled()) {
        log.debug("Publishing event: " + e);
    }
    getContext(event.getSession().getServletContext()).publishEvent(e);
}

getContext(event.getSession().getServletContext())得到的是Root ApplicationContext,所以要把SessionRegistryImpl Bean注册到Root ApplicationContext,这样SessionRegistryImpl的onApplicationEvent方法才能接收上面发布的HttpSessionDestroyedEvent事件.

public void onApplicationEvent(SessionDestroyedEvent event) {
    String sessionId = event.getId();
    removeSessionInformation(sessionId);
}

这里就看removeSessionInformation(sessionId);这里就会对SessionRegistryImpl相关信息进会更新.进而通过SessionRegistryImpl获得那些用户登录了,一个用户有多少个SessionInformation都进行了同步.

再来讨论getContext(event.getSession().getServletContext())

ApplicationContext getContext(ServletContext servletContext) {
    return SecurityWebApplicationContextUtils.findRequiredWebApplicationContext(servletContext);
}
public static WebApplicationContext findRequiredWebApplicationContext(ServletContext servletContext) {
    WebApplicationContext wac = _findWebApplicationContext(servletContext);
    if (wac == null) {
        throw new IllegalStateException("No WebApplicationContext found: no ContextLoaderListener registered?");
    }
    return wac;
}
private static WebApplicationContext _findWebApplicationContext(ServletContext sc) {
    //从下面调用看,得到的是Root ApplicationContext,而不是Servlet ApplicationContext
    WebApplicationContext wac = getWebApplicationContext(sc);
    if (wac == null) {
        Enumeration attrNames = sc.getAttributeNames();
        while (attrNames.hasMoreElements()) {
            String attrName = attrNames.nextElement();
            Object attrValue = sc.getAttribute(attrName);
            if (attrValue instanceof WebApplicationContext) {
                if (wac != null) {
                    throw new IllegalStateException("No unique WebApplicationContext found: more than one " +
                            "DispatcherServlet registered with publishContext=true?");
                }
                wac = (WebApplicationContext) attrValue;
            }
        }
    }
    return wac;
}
public static WebApplicationContext getWebApplicationContext(ServletContext sc) {
    return getWebApplicationContext(sc, WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE);
}

再假设得到的Servlet ApplicationContext,它还有parent(Root ApplicationContext),那么它也会通知Root ApplicationContext下监听SessionDestroyedEvent事件的Bean,(哈哈,但是没有那么多的如果);
但我还要如果用户就想在servlet注册SessionRegistryImpl,我觉得你可以继承HttpSessionEventPublisher,重写getContext方法了

针对于servlet容器的session,至于session过期,如果想测试,可以去改一下session的有效期短一点,然后等待观察.下面是我的测试web.xml全部内容

    
        3
    

对于用户主动关闭浏览器,服务端是没有马上触发sessionDestroyed的,等待session过期应该是大多数开发者的需求.

关于踢下线功能:使用org.springframework.security.core.session.SessionRegistry#getAllSessions就可以得到某个用户的所有SessionInformation,SessionInformation当然包括sessionId,剩下的问题就是根据sessionId获取session,再调用session.invalidate()就可以完成需求了.但是javax.servlet.http.HttpSessionContext#getSession已过期,并且因为安全原因没有替代方案,所以从servlet api2.1以后的版本,此路是不通的.
spring security提供了org.springframework.security.core.session.SessionInformation#expireNow,它只是标志了一下过期,直到下次用户请求被org.springframework.security.web.session.ConcurrentSessionFilter#doFilter拦截,

HttpSession session = request.getSession(false);
if (session != null) {
    SessionInformation info = sessionRegistry.getSessionInformation(session.getId());
    if (info != null) {
        if (info.isExpired()) {
            // Expired - abort processing
            doLogout(request, response);
            //其它代码忽略
        }
    }
}

这里就会触发了用户登出.还有一种思路,session保存在redis,直接从redis删除某个session数据,详细看org.springframework.session.SessionRepository,不太推荐这么干.

还有SessionRegistryImpl实现的并发控制靠以下两个变量实现的用户在线列表,重启应用这两个实例肯定会销毁,
/**  */
private final ConcurrentMap> principals = new ConcurrentHashMap>();
/**  */
private final Map sessionIds = new ConcurrentHashMap();

既然分布式应用也会有问题,这时就要实现自己的SessionRegistry,将session的信息应保存到一个集中的地方进行管理.