[HttpPost]
public ContentResult PostDatas（）
{
		HttpPostedFileBase file = Request.Files["file"];
            var fileName = file.FileName;
            //var filePhan = Server.MapPath("/FilesInfos/");
            var filePhan = Server.MapPath(string.Format("~/{0}", "FilesInfos"));
            //file.SaveAs(filePhan+ fileName);
            file.SaveAs(Path.Combine(filePhan, fileName));
            return Content(@"<script>alert('上传成功');loction.href='/ExamInfos/GetData'</script>");
}

<form action="/ExamInfos/PostDatas" method="post" enctype="multipart/form-data">
            <input id="file" type="file" name="file"/>
            <input type="submit" name="name" value="上传" />
        </form>