我正在尝试编写一个过滤器，它检查用户是否已登录，以防万一没有将他重定向到登录页面。以前我有过滤器实际上什么也没做-_-在这里，使用这个过滤器一切正常，会话无效：
public void doFilter(ServletRequest req, ServletResponse res,
FilterChain chain) throws IOException, ServletException {
HttpServletRequest request = (HttpServletRequest) req;
HttpSession session = request.getSession();
if (session == null || session.getAttribute("UserName") == null) {
String command = request.getParameter("command");
request.setAttribute("command", "login");
// String page = ConfigurationManager.getInstance().getProperty(
// ConfigurationManager.LOGIN_PAGE_PATH);
} else {
String username = (String) session.getAttribute("UserName");
UserRole role;
try {
role = UserDAOImpl.getUserRole(username);
session.setAttribute("role", role);
} catch (DAOTechnicException e) {
logger.error(e);
} catch (DAOLogicException e) {
logger.error(e);
}
}
chain.doFilter(req, res);
}
当我使会话无效时，它会进入 (if session == null) 块，一切正常。
但现在我有另一个过滤器，这里是：
public class UserCheckFilter implements Filter {
static class FilteredRequest extends HttpServletRequestWrapper {
public FilteredRequest(ServletRequest request) {
super((HttpServletRequest) request);
}
public String getParameter(String paramName) {
String value = super.getParameter(paramName);
if(value!=null){
if (value.equals("login")) {
return value;
}
HttpSession session = super.getSession();
if (session == null || session.getAttribute("UserName") == null) {
value = "login";
}
}
return value;
}
}
/**
* Checks if user logged in and if not redirects to login page
*/
@Override
public void doFilter(ServletRequest req, ServletResponse res,
FilterChain chain) throws IOException, ServletException {
HttpServletRequest request = (HttpServletRequest) req;
HttpSession session = request.getSession(false);
if (session == null || session.getAttribute("UserName") == null) {
if(request.getParameter("command")!=null){
String command = request.getParameter("command");
if(!command.equals("login")){
FilteredRequest filtrequest = new FilteredRequest(request);
String filteredvalue = filtrequest.getParameter("command");
chain.doFilter(filtrequest, res);
}else{
chain.doFilter(req, res);
}
}else{
chain.doFilter(req, res);
}
} else {
String username = (String) session.getAttribute("UserName");
UserRole role;
chain.doFilter(req, res);
try {
role = UserDAOImpl.getUserRole(username);
session.setAttribute("role", role);
} catch (DAOTechnicException e) {
logger.error(e);
} catch (DAOLogicException e) {
logger.error(e);
}
}
}
在其中我包装了 getParameter 方法并检查未登录的用户是否正在尝试访问用户或管理页面。但是当我使会话无效时，它不会无效，即所有参数都保持不变，然后在过滤器中检查会话是否！= null，它不为 null，并且在行 session.setAttribute("role", role) ; 我收到异常“会话已失效”
这是我使会话无效的方法：
if(request.getSession(false)!=null){
request.getSession().invalidate();
}
String page = ConfigurationManager.getInstance().getProperty(
ConfigurationManager.LOGIN_PAGE_PATH);
return page;
并在 servlet U 中使用
RequestDispatcher dispatcher = getServletContext()
.getRequestDispatcher(page);
dispatcher.forward(request, response);
顺便说一句，使会话无效的事情仅在第二个过滤器中发生
ps 抱歉可能是愚蠢的问题，但我真的不知道出了什么问题，所以任何建议都将不胜感激。