摘要：每个人遇到的问题都不一样，在网上找了一大圈都没有解决到我的问题！因为我的环境如标题所示，解决了这个问题。

主要问题：在于响应头的设置

Controller：

        [HttpPost]
        public ContentResult UploadFile(string user = WinTabConst.Space, int type = ConfigConst.Zero, string imgType = WinTabConst.Space, int objId = ConfigConst.Zero, DateTime? createDateTime = null)
        {
            HttpPostedFileBase imgFile = Request.Files["imgFile"];

            AttachmentBLL attachmentBll;
            if (!string.IsNullOrEmpty(user))
                attachmentBll = new AttachmentBLL(user);
            else
                attachmentBll = new AttachmentBLL();
            int userId = 0;
            users userModel = attachmentBll.CurUser;
            if (user != null)
                userId = userModel.UserID;
            return Content(JavascriptHelper.JsonSerializer.Serialize(attachmentBll.UploadFile(true, "", imgFile, type, imgType, objId, userId, createDateTime)));
        }

$.ajaxFileUpload(
       {
           url: "/Companies/attachment/UploadFile",
           data: { "objId": objId, "createDateTime": createDateTime, "dir": "", "type": "2", "userid": UserID, "user": $.cookie('LoginInfo') },
           type: "post",
           secureuri: false,
           dataType: "text",
           fileElementId: "imgFile",
           success: function (data) {
               if (data != null && data =http://www.mamicode.com/= "") {//这个判断是因为当时格式为 json，IE接收到的 data为 "",但是图上又是传成功的问题>


.net mvc4 +  ajaxfileupload.js 解决IE浏览器中弹出下载对话框问题