不使用IWFileUploader，直接使用ajax上传附件到服务器

//带附件上传
if (file){
var fname=encodeURIComponent(file.name);
//IIS 必须使用FormData()
var fdata=new
FormData();
//sa模式不支持 FormData，IW后台没对formdata数据进行处理，只能直接send file
if (_iislib==true){
fdata.append("uploadempimage",file);
}
//关键参数，否则后台IW程序不给你上传文件
param.IWFileUploader=true;

$.ajax({
url: obj2url(param,
pa.url),
type: 'post',
beforeSend:
function (xhr) {
xhr.setRequestHeader("X-Requested-With",
"XMLHttpRequest");
xhr.setRequestHeader("X-File-Name",
fname);
if (!_iislib){
xhr.setRequestHeader("Content-Type",
"application/octet-stream");
}

xhr.setRequestHeader("X-Mime-Type",
file.type); 
},
cache: false,
contentType:
false,
processData:
false,
dataType:'json',                
data:(_iislib==true) ?fdata:file, //iis后台 传formdata ,sa 模式直接传 file
success:
function (result,status,xhr) {
if (result.success==true) {
grid.datagrid('reload');
}
$.messager.show({title:"提示",msg:result.message});
},
complete:function(xhr,status){
$.messager.progress('close');
if (status!=='success'){$.messager.show({title:'错误',msg:'保存失败！<br>状态:'+status})}
}
});
}