1.首先要再SessionFilter中進行ajax請求過濾，程式碼如下:

if (session == null)	//session不存在
{
    String ajaxSubmit = servletRequest.getHeader("X-Requested-With");
        if(ajaxSubmit != null && ajaxSubmit.equals("XMLHttpRequest")){   
            PrintWriter printWriter = servletResponse.getWriter();   
	    printWriter.print("timeout");   
	    printWriter.flush();   
	    printWriter.close();
	}else{  
	    //跳轉回首頁
	    servletResponse.sendRedirect("開始頁面");
	}
				
}
 

function getTopWinow() {
 var p = window;
 while (p != p.parent) {
  p = p.parent;
 }
 return p;
}
$.ajaxSetup({
    type : 'POST',
    dataFilter : function(data, type) {
        //alert("debug");
	if (data == "timeout" || data == "[object XMLDocument]") {// ajax請求，發現session過期，重新重新整理頁面，跳轉到登入頁面
	    var top = getTopWinow();
	    top.location.href = '開始頁面';
	} else {
	    return data;
	}
}