Filter 权限过滤 缓存过滤

	--------------------权限过滤
		public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse,
			FilterChain filterChain) throws IOException, ServletException {
			HttpServletRequest req=(HttpServletRequest)servletRequest;
			HttpServletResponse res=(HttpServletResponse)servletResponse;
			String uri=req.getRequestURI();
			String s=uri.substring(uri.indexOf("/", 1), uri.length());
			if(!"/login.jsp".equals(s)){
				if(req.getSession(false)==null || req.getSession(false).getAttribute("user") == null){
					System.out.println("rrrrrrrrrrrrr");
					res.sendRedirect(req.getContextPath()+"/login.jsp");
					return;
				}
			}
			filterChain.doFilter(req, res);
		}

		-------------------缓存过滤
		public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse,
			FilterChain filterChain) throws IOException, ServletException {
			HttpServletRequest req=(HttpServletRequest)servletRequest;
			HttpServletResponse res=(HttpServletResponse)servletResponse;
			res.setHeader("Cache-Control", "max-age=10000");
			filterChain.doFilter(req, res);
		}