HomeController.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Web;
using System.Web.Mvc;

namespace jQuery_File_Upload.MVC3.Controllers
{
    public class HomeController : Controller
    {
        private string StorageRoot
        {
            get { return Path.Combine(Server.MapPath("~/Files")); }
        }

        public ActionResult Index()
        {
            return View();
        }

        //DONT USE THIS IF YOU NEED TO ALLOW LARGE FILES UPLOADS
        [HttpGet]
        public void Delete(string id)
        {
            var filename = id;
            var filePath = Path.Combine(Server.MapPath("~/Files"), filename);

            if (System.IO.File.Exists(filePath))
            {
                System.IO.File.Delete(filePath);
            }
        }

        //DONT USE THIS IF YOU NEED TO ALLOW LARGE FILES UPLOADS
        [HttpGet]
        public void Download(string id)
        {
            var filename = id;
            var filePath = Path.Combine(Server.MapPath("~/Files"), filename);

            var context = HttpContext;

            if (System.IO.File.Exists(filePath))
            {
                context.Response.AddHeader("Content-Disposition", "attachment; filename=\"" + filename + "\"");
                context.Response.ContentType = "application/octet-stream";
                context.Response.ClearContent();
                context.Response.WriteFile(filePath);
            }
            else
                context.Response.StatusCode = 404;
        }

        //DONT USE THIS IF YOU NEED TO ALLOW LARGE FILES UPLOADS
        [HttpPost]
        public ActionResult UploadFiles()
        {
            var r = new List<ViewDataUploadFilesResult>();

            foreach (string file in Request.Files)
            {
                var statuses = new List<ViewDataUploadFilesResult>();
                var headers = Request.Headers;

                if (string.IsNullOrEmpty(headers["X-File-Name"]))
                {
                    UploadWholeFile(Request, statuses);
                }
                else
                {
                    UploadPartialFile(headers["X-File-Name"], Request, statuses);
                }

                JsonResult result = Json(statuses);
                result.ContentType = "text/plain";

                return result;
            }

            return Json(r);
        }

        private string EncodeFile(string fileName)
        {
            return Convert.ToBase64String(System.IO.File.ReadAllBytes(fileName));
        }

        //DONT USE THIS IF YOU NEED TO ALLOW LARGE FILES UPLOADS
        //Credit to i-e-b and his ASP.Net uploader for the bulk of the upload helper methods - https://github.com/i-e-b/jQueryFileUpload.Net
        private void UploadPartialFile(string fileName, HttpRequestBase request, List<ViewDataUploadFilesResult> statuses)
        {
            if (request.Files.Count != 1) throw new HttpRequestValidationException("Attempt to upload chunked file containing more than one fragment per request");

            var file = request.Files[0];
            var fullName = Path.Combine(StorageRoot, Path.GetFileName(fileName));

            using (var fs = new FileStream(fullName, FileMode.Append, FileAccess.Write))
            {
                file.InputStream.CopyTo(fs);
            }
            
            statuses.Add(new ViewDataUploadFilesResult()
            {
                name = fileName,
                size = file.ContentLength,
                type = file.ContentType,
                url = "/Home/Download/" + fileName,
                delete_url = "/Home/Delete/" + fileName,
                thumbnail_url = @"data:image/png;base64," + EncodeFile(fullName),
                delete_type = "GET",
            });
        }

        //DONT USE THIS IF YOU NEED TO ALLOW LARGE FILES UPLOADS
        //Credit to i-e-b and his ASP.Net uploader for the bulk of the upload helper methods - https://github.com/i-e-b/jQueryFileUpload.Net
        private void UploadWholeFile(HttpRequestBase request, List<ViewDataUploadFilesResult> statuses)
        {
            for (int i = 0; i < request.Files.Count; i++)
            {
                var file = request.Files[i];

                var fullPath = Path.Combine(StorageRoot, Path.GetFileName(file.FileName));

                file.SaveAs(fullPath);

                statuses.Add(new ViewDataUploadFilesResult()
                {
                    name = file.FileName,
                    size = file.ContentLength,
                    type = file.ContentType,
                    url = "/Home/Download/" + file.FileName,
                    delete_url = "/Home/Delete/" + file.FileName,
                    thumbnail_url = @"data:image/png;base64," + EncodeFile(fullPath),
                    delete_type = "GET",
                });
            }
        }
    }

    public class ViewDataUploadFilesResult
    {
        public string name { get; set; }
        public int size { get; set; }
        public string type { get; set; }
        public string url { get; set; }
        public string delete_url { get; set; }
        public string thumbnail_url { get; set; }
        public string delete_type { get; set; }
    }
}