Spring Security实现禁止用户重复登陆（配置及原理）
系统使用了Spring Security做权限管理，现在对于系统的用户，需要改动配置，实现无法多地登陆。
一、SpringMVC项目，配置如下：
首先在修改Security相关的XML，我这里是spring-security.xml，修改UsernamePasswordAuthenticationFilter相关Bean的构造配置
加入
<property name="sessionAuthenticationStrategy" ref="sas" />
新增sas的Bean及其相关配置
<bean id="sas" class="org.springframework.security.web.authentication.session.CompositeSessionAuthenticationStrategy"> <constructor-arg> <list> <bean class="org.springframework.security.web.authentication.session.ConcurrentSessionControlAuthenticationStrategy"> <constructor-arg ref="sessionRegistry"/> <!-- 这里是配置session数量，此处为1，表示同一个用户同时只会有一个session在线 --> <property name="maximumSessions" value="1" /> <property name="exceptionIfMaximumExceeded" value="false" /> </bean> <bean class="org.springframework.security.web.authentication.session.SessionFixationProtectionStrategy"> </bean> <bean class="org.springframework.security.web.authentication.session.RegisterSessionAuthenticationStrategy"> <constructor-arg ref="sessionRegistry"/> </bean> </list> </constructor-arg> </bean> <bean id="sessionRegistry" class="org.springframework.security.core.session.SessionRegistryImpl" />
加入ConcurrentSessionFilter相关Bean配置
<bean id="concurrencyFilter" class="org.springframework.security.web.session.ConcurrentSessionFilter"> <constructor-arg name="sessionRegistry" ref="sessionRegistry" /> <constructor-arg name="sessionInformationExpiredStrategy" ref="redirectSessionInformationExpiredStrategy" /> </bean> <bean id="redirectSessionInformationExpiredStrategy" class="org.springframework.security.web.session.SimpleRedirectSessionInformationExpiredStrategy"> <constructor-arg name="invalidSessionUrl" value="/login.html" /> </bean>
二、SpringBoot项目，配置如下：
待补充。。。。。
三、Bean配置说明
SessionAuthenticationStrategy：该接口中存在onAuthentication方法用于对新登录用户进行session相关的校验。
查看UsernamePasswordAuthenticationFilter及其父类代码，可以发现在doFilter中存在sessionStrategy.onAuthentication(authResult, request, response);方法
但UsernamePasswordAuthenticationFilter中的sessionStrategy对象默认为NullAuthenticatedSessionStrategy，即不对session进行相关验证。
如本文配置，建立id为sas的CompositeSessionAuthenticationStrategy的Bean对象。
CompositeSessionAuthenticationStrategy可以理解为一个托管类，托管所有实现SessionAuthenticationStrategy接口的对象，用来批量托管执行onAuthentication函数
这里CompositeSessionAuthenticationStrategy中注入了三个对象，关注ConcurrentSessionControlAuthenticationStrategy，它实现了对于session并发的控制
UsernamePasswordAuthenticationFilter的Bean中注入新配置的sas，用于替换原本的NullAuthenticatedSessionStrategy
ConcurrentSessionFilter的Bean用来验证session是否失效，并通过SimpleRedirectSessionInformationExpiredStrategy将失败访问进行跳转。
四、代码流程说明（这里模拟用户现在A处登录，随后用户在B处登录，之后A处再进行操作时会返回失败，提示重新登录）
1、用户在A处登录，UsernamePasswordAuthenticationFilter调用sessionStrategy.onAuthentication进行session验证
2、ConcurrentSessionControlAuthenticationStrategy中的onAuthentication开始进行session验证，服务器中保存了登录后的session
/** * In addition to the steps from the superclass, the sessionRegistry will be updated * with the new session information. */ public void onAuthentication(Authentication authentication, HttpServletRequest request, HttpServletResponse response) { //根据所登录的用户信息，查询相对应的现存session列表 final List<SessionInformation> sessions = sessionRegistry.getAllSessions( authentication.getPrincipal(), false); int sessionCount = sessions.size(); //获取session并发数量，对于XML中的maximumSessions int allowedSessions = getMaximumSessionsForThisUser(authentication); //判断现有session列表数量和并发控制数间的关系 //如果是首次登录，根据xml配置，这里应该是0<1，程序将会继续向下执行， //最终执行到SessionRegistryImpl的registerNewSession进行新session的保存 if (sessionCount < allowedSessions) { // They haven't got too many login sessions running at present return; } if (allowedSessions == -1) { // We permit unlimited logins return; } if (sessionCount == allowedSessions) { //获取本次http请求的session HttpSession session = request.getSession(false); if (session != null) { // Only permit it though if this request is associated with one of the // already registered sessions for (SessionInformation si : sessions) { //循环已保存的session列表，判断本次http请求session是否已经保存 if (si.getSessionId().equals(session.getId())) { //本次http请求是有效请求，返回执行下一个filter return; } } } // If the session is null, a new one will be created by the parent class, // exceeding the allowed number } //本次http请求为新请求，进入具体判断 allowableSessionsExceeded(sessions, allowedSessions, sessionRegistry); }
/** * Allows subclasses to customise behaviour when too many sessions are detected. * * @param sessions either <code>null</code> or all unexpired sessions associated with * the principal * @param allowableSessions the number of concurrent sessions the user is allowed to * have * @param registry an instance of the <code>SessionRegistry</code> for subclass use * */ protected void allowableSessionsExceeded(List<SessionInformation> sessions, int allowableSessions, SessionRegistry registry) throws SessionAuthenticationException { //根据exceptionIfMaximumExceeded判断是否要将新http请求拒绝 //exceptionIfMaximumExceeded也可以在XML中配置 if (exceptionIfMaximumExceeded || (sessions == null)) { throw new SessionAuthenticationException(messages.getMessage( "ConcurrentSessionControlAuthenticationStrategy.exceededAllowed", new Object[] { Integer.valueOf(allowableSessions) }, "Maximum sessions of {0} for this principal exceeded")); } // Determine least recently used session, and mark it for invalidation SessionInformation leastRecentlyUsed = null; //若不拒绝新请求，遍历现存seesion列表 for (SessionInformation session : sessions) { //获取上一次/已存的session信息 if ((leastRecentlyUsed == null) || session.getLastRequest() .before(leastRecentlyUsed.getLastRequest())) { leastRecentlyUsed = session; } } //将上次session信息写为无效（欺骗） leastRecentlyUsed.expireNow(); }
3、用户在B处登录，再次通过ConcurrentSessionControlAuthenticationStrategy的检查，将A处登录的session置于无效状态，并在session列表中添加本次session
4、用户在A处尝试进行其他操作，ConcurrentSessionFilter进行Session相关的验证，发现A处用户已经失效，提示重新登录
public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException { HttpServletRequest request = (HttpServletRequest) req; HttpServletResponse response = (HttpServletResponse) res; //获取本次http请求的session HttpSession session = request.getSession(false); if (session != null) { //从本地session关系表中取出本次http访问的具体session信息 SessionInformation info = sessionRegistry.getSessionInformation(session .getId()); //如果存在信息，则继续执行 if (info != null) { //判断session是否已经失效（这一步在本文4.2中被执行） if (info.isExpired()) { // Expired - abort processing if (logger.isDebugEnabled()) { logger.debug("Requested session ID " + request.getRequestedSessionId() + " has expired."); } //执行登出操作 doLogout(request, response); //从XML配置中的redirectSessionInformationExpiredStrategy获取URL重定向信息，页面跳转到登录页面 this.sessionInformationExpiredStrategy.onExpiredSessionDetected(new SessionInformationExpiredEvent(info, request, response)); return; } else { // Non-expired - update last request date/time sessionRegistry.refreshLastRequest(info.getSessionId()); } } } chain.doFilter(request, response); }
5、A处用户只能再次登录，这时B处用户session将会失效重登，如此循环
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