String sessionId = ((HttpServletRequest)request).getSession().getId();
if( onlineUserCache.get(username) != null
&& onlineUserCache.get(username).getValue() != null ){
OnlineUser online = (OnlineUser)onlineUserCache.get(username).getValue();
if( !sessionId.equals(online.getSessionid()) ){
/*
String msg = "时间["+SDF.format(online.getLoginTime())+"],用户["
+online.getUsername()+"]在IP["+online.getIp()+"]地址已经登录!";
request.setAttribute(FormAuthenticationFilter