Java过滤器应用-对Ajax请求做Session失效判断

 过滤器常用来对Session过期做判断

 Layout.js　　

1.为ajax请求添加标识　　　

2.无论ajax请求成功与否，complete函数终会执行

// 全局Ajax设置, 用于session过期后的跳转
function ajaxSetup() {
    $.ajaxSetup({
        timeout : 10000,
        beforeSend : function(xhr) {
            //添加ajax请求标识
            xhr.setRequestHeader("ajaxReq", "ajax");
        },
        complete : function(xhr, ts) {
            if (xhr.statusText == 'sessiontimeout' && xhr.status == 403) {
                // 跳转
                window.location.href = "login.jsp";
            }
        }
    });
}

请求过滤器，Session过期则修改请求状态为403（或其他），设置过期标识sessionState为timeout，便于ajax回调函数判断。

public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {

        HttpServletRequest req = (HttpServletRequest) request;
        HttpServletResponse res = (HttpServletResponse) response;
        String servletPath = req.getServletPath();
        
        if(except.contains(req.getRequestURI())){
            chain.doFilter(request, response);
        }
        
        Object sessionObj = req.getSession().getAttribute(key);
        if(sessionObj==null){
            //如果是ajax请求
            if(req.getHeader("ajaxReq")!=null && req.getHeader("ajaxReq").equals("ajax")){
                res.setHeader("sessionState", "timeout");
                res.setStatus(403);
                return;
            }else{
                chain.doFilter(request, response);
                String contextPath = req.getContextPath();
                String redirect = servletPath + "?" + StringUtils.defaultString(req.getQueryString());
                res.sendRedirect(contextPath + forward + "?redirect=" + URLEncoder.encode(redirect, "UTF-8"));
            }
            
        }else{
            // pass the request along the filter chain
            chain.doFilter(request, response);
            System.out.println("chain.do after");
        }
        
    }

 目前发现ajax全局设置对load函数无效。