struts2获取sessionid并存储在内存中

HttpServletRequest request = ServletActionContext.getRequest();

String sessionId = request.getSession().getId();
UserManager.getInstance().addSessionID(sessionId, userId);

/*
* 添加用户到session中
* */
public void addSessionID(String sessionId, String userId) {
if(sessionUserMap == null){
sessionUserMap = new HashMap<String, String>();
}

sessionUserMap.put(sessionId, userId);
}
//注销
public void logout(String sessionId){
if(sessionUserMap.containsKey(sessionId)){
sessionUserMap.remove(sessionId);
}
}

//获取当前用户数量
public int getCurrentUserCount(){
return sessionUserMap == null ? 0 : sessionUserMap.size();
}