ajax請求下載文件無反應

ajax 只能處理字符串請求，沒法處理二進制文件！！！

 var form=$("<form>");
						form.attr("style","display:none");
						form.attr("target","");
						form.attr("method","post");
						form.attr("action","#springUrl('/cloudSign/downAll.htm')");
						var input1=$("<input>");
						input1.attr("type","hidden");
						input1.attr("name","cloudSignContractVo");
						input1.attr("value", JSON.stringify(urls));
						$("body").append(form);
						form.append(input1);
						form.submit();