Ajax异步加载时产生滚动进度条

 j$.ajax({

         cache: true,

         type: "POST",

         url:"../sellingdataquery/mitacSellingdataAction!download.action",

         data:j$('#formcmj').serialize(),

         contentType:"application/vnd.ms-excel",

         beforeSend: function(XMLHttpRequest) { j$("body").append('

'); },

         error: function(request) {

             alert("Connection error");

         },

         success: function(data) {

             j$("#load").remove();

         }

     });