Web 开发中Ajax的Session 超时处理方法

  public void doFilter(ServletRequest request, ServletResponse response,      FilterChain chain) throws IOException, ServletException {    HttpServletRequest servletRequest=(HttpServletRequest)request;    HttpServletResponse servletResponse=(HttpServletResponse)response;    // 判断是否是 Ajax 请求，因为 Ajax 请求会追加 x-requested-with=XMLHttpRequest    if("XMLHttpRequest".equalsIgnoreCase(servletRequest.getHeader("x-requested-with"))){      servletResponse.addHeader("sessionstatus", "timeout");    }        // 后续代码省略......  }

// 全局的ajax访问，处理ajax清求时sesion超时$.ajaxSetup({  type: POST,  contentType:"application/json;charset=utf-8",  // 使用 complete 捕获结果，做超时处理  complete: function (XMLHttpRequest, textStatus) {    var data = XMLHttpRequest.responseText;    if (data == "timeout") {      if( window.top != window.self ){        window.top.location = "${pageContext.request.contextPath}";      }    }  }});