public void doFilter(req, resp, chain) {
	HttpServletRequest request = (HttpServletRequest) req;
	HttpSession session = request.getSession();
	if (request.getRequestURI().contains("/signin")) {
		chain.doFilter(req, resp);
	} else {   
		synchronized(session) {
			if(session.getAttribute("login") == null) {
				((HttpServletResponse) resp).sendRedirect(request.getContextPath() + "/signin")
				return; 
			}   
			chain.doFilter(req, resp);
		}
	}
}