using System.IO;

public string UpdatePic(HttpPostedFileBase pic)        {            string filePath = null;            string filename = null;            try            {                string path = Server.MapPath("~/Upload/");                if (!Directory.Exists(path))                {                    Directory.CreateDirectory(path);                }                filename = pic.FileName;//获得文件上传全目录                //filename = DateTime.Now.ToString("yyyyMMddHHmmssfff");                int place = filename.LastIndexOf(".") + 1;//获得文件扩展名的位置                string extname = filename.Substring(place).ToLower();//得到文件扩展名                              string allowedType = "jpg|bmp|jpeg|psd|png";//允许上传文件类型                long allowedSize = 512000 * 1024;//允许上传最大文件大小                if (allowedType.Contains(extname) && pic.ContentLength < allowedSize)                {                    filePath = path + filename;                    pic.SaveAs(filePath);                }                else                {                    return null;                }            }            catch (Exception err)            {                throw new Exception(err.Message);            }            return filename;        }

HttpPostedFileBase file = Request.Files["pic"];      if (file.ContentLength != 0)                    {                        string filename = UpdatePic(file);                        model.Url = @"..\..\Upload\" + filename;                    }

                @Html.LabelFor(model=>model.Url)                                                                 

@using (Html.BeginForm("AddActivity", "Activity", FormMethod.Post, new { enctype = "multipart/form-data"}))

 

这种方法兼容性不好，不建议使用，建议使用 Uploadify插件，参考