<form action="/Save" id="mainForm" method="post" enctype="multipart/form-data">

 <div class="portlet-body form-horizontal form-bordered form-row-stripped">

        <div class="row-fluid">

            <div class="control-group">

               导入文件：<input type="file" name="FilePath" class="file" id="fileField">

            </div>

        </div>

    </div>

    <div class="form-actions navbar-fixed-bottom">

        <button id="submit" type="submit" class="btn blue"><i class="icon-ok"></i>提交</button>

    </div>

</form>

<script src="/Content/Scripts/jquery.form.js"></script>

<script>

    $(function() {
$("#mainForm").attr("enctype", "multipart/form-data");

        $("#fileField").on("change", function() {

            $("#mainForm").attr("action", "/ImportFile");

            $('form').ajaxSubmit({

                success: function(data) {

                    if (data) {

                       //todo

                    } else {

                        alert("解析文件异常，请检查上传文件");

                    }

                    $("#mainForm").attr("action", "/Save");

                },

            });

        });

    });

</script>

[HttpPost]

public JsonResult ImportFile(FormCollection collection)

{

    object model = null;

    try

    {

        HttpPostedFileBase fostFile = Request.Files["FilePath"];

        Stream streamfile = fostFile.InputStream;

        var reader = new StreamReader(streamfile);

        string text = reader.ReadToEnd();
        //解析文件，文件内容是XML

        model = XmlHelper.XmlDeserialize<Model>(text, Encoding.UTF8);

    }

    catch (Exception ex)

    {

        throw  new Exception();

    }

    return Json(model, JsonRequestBehavior.AllowGet);

}