ASP.NET MVC上传文件的几种方法

1.Form表单提交

<p>Form提交</p>
<form action="@Url.Action("SavePictureByForm")" enctype="multipart/form-data" method="post">
    <input id="pic" name="pic" type="file" />
    <input type="submit" value="提交" />
</form>

2.Ajax.BeginForm,原理也是Form表单提交

<p>Ajax.BeginForm</p>
@using(Ajax.BeginForm("SavePictureByForm", null, new AjaxOptions() { OnSuccess = "PostSuc", OnFailure = "PostFail", HttpMethod = "Post"}, new {enctype = "multipart/form-data"}))
{
   <input type="file" name="pic" id="pic" multiple="multiple" />
   <input type="submit" value="提交" />
}

以上两种方式,在后台用同一种方法可以获取数据: 但是这两种方法会造成页面刷新,有时会影响用户操作.

 public ActionResult SavePictureByForm()
        {
            HttpFileCollectionBase files = Request.Files;
            var file = files[0];
            bool isOk = false;
            string msg = string.Empty;
            //....OtherDO


            return Content("<script>window.location.href='/home/index';</script>");
        }

3.Ajax提交  用此方法需要用到FileReader类,再获取到文件的Base64数据,将Base64数据Post过去

<p>Ajax:以上传图片为例</p>
<input type="file" id="picAjax"/>
<input type="button" id="submitPic" value="提交" />
<img id="selImg"  src="" alt="用作图片预览" />

    var picString = "";
    $(function () {
        $("#picAjax").change(function (e) {
            var file = e.delegateTarget.files[0];
            //在此可以对选择的文件进行判断:文件类型 文件大小等
            //.....
            
            var reader = new FileReader();
            reader.readAsDataURL(file);
            reader.onload = function (ret) {
                picString = reader.result
                //预览图片
                $("#selImg").attr({ "src": picString });
            }
        });

        $("#submitPic").click(function () {
            $.ajax("home/SavePicture", {
                type: "post",
                datatype: "json",
                data: picString,
                error: function () { },
                success: function (result) {
                    if (result) {
                        alert(result.msg);
                    }
                }
            });
        });

后端接收

 [HttpPost]
        public ActionResult SavePicture(string picString)
        {
            bool isOk = false;
            string msg = string.Empty;
            //其他操作
            //.........
            //.........
            return Json(new { suc = isOk, msg = msg });
        }

第三种方法做到了真正异步提交.但是如果选择的文件较大,可能会出现问题(未测试).

对于图片预览 前两种方法也可用base64数据进行图片预览.