这篇文章主要介绍了Spring Security实现禁止用户重复登陆的配置原理,文中通过示例代码介绍的非常详细，对大家的学习或者工作具有一定的参考学习价值,需要的朋友可以参考下
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
略
三、Bean配置说明
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
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持呐喊教程。
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