Introduction to the most complete method of uploading images in C#

public ActionResult Upload()
    {
      string imgurl = "";
      foreach (string key in Request.Files)
      {
        //这里只测试上传第一张图片file[0]
        HttpPostedFileBase file0 = Request.Files[key];
        //转换成byte,读取图片MIME类型
        Stream stream;
        int size = file0.ContentLength / 1024; //文件大小KB
        if (size > 1024)
        {
          return Content(ReturnMsg(Enum_Return.失败, "图片不能超过1M：", null));
        }
        byte[] fileByte = new byte[2];//contentLength，这里我们只读取文件长度的前两位用于判断就好了，这样速度比较快，剩下的也用不到。
        stream = file0.InputStream;
       stream.Read(fileByte, 0, 2);//contentLength，还是取前两位
        //获取图片宽和高
        //System.Drawing.Image image = System.Drawing.Image.FromStream(stream);
        //int width = image.Width;
        //int height = image.Height;
        string fileFlag = "";
        if (fileByte != null && fileByte.Length > 0)//图片数据是否为空
        {
          fileFlag = fileByte[0].ToString()  fileByte[1].ToString();
        }
        string[] fileTypeStr = { "255216", "7173", "6677", "13780" };//对应的图片格式jpg,gif,bmp,png
        if (fileTypeStr.Contains(fileFlag))
        {
          string action = Request["action"];
          string path = "/uploads/";
          switch (action)
          {
            case "headimage":
              path  = "headimage/";
              break;
            case "blogtype":
              path  = "blogtype/";
              break;
          }
          string fullpath = path  UserInfo.userID  "/";
          if (!Directory.Exists(Server.MapPath(fullpath)))
          {
            Directory.CreateDirectory(Server.MapPath(fullpath));
          }
          Request.Files[key].SaveAs(Server.MapPath(fullpath  Request.Files[key].FileName));
          imgurl = fullpath  Request.Files[key].FileName;
        }
        else
        {
          return Content(ReturnMsg(Enum_Return.失败, "图片格式不正确：" fileFlag, null));
        }
        stream.Close();
      }
      return Content(ReturnMsg(Enum_Return.成功, "上传成功", imgurl));
    }

public void ProcessRequest(HttpContext context)
  {
    context.Response.ContentType = "application/json";
    HttpPostedFile _upfile = context.Request.Files["File"];
    if (_upfile.ContentLength < 500000)
    {
      if (string.IsNullOrEmpty(_upfile.FileName))
      {
         context.Response.Write("请上传图片");
      }
      string fileFullname = _upfile.FileName;
      string dataName = DateTime.Now.ToString("yyyyMMddhhmmss");
      string fileName = fileFullname.Substring(fileFullname.LastIndexOf("\\")  1);
      string type = fileFullname.Substring(fileFullname.LastIndexOf(".")  1);
      if (type == "bmp" || type == "jpg" || type == "gif" || type == "JPG" || type == "BMP" || type == "GIF")
      {
        _upfile.SaveAs(HttpContext.Current.Server.MapPath("photo")  "\\"  dataName  "."  type);
        HttpCookie cookie = new HttpCookie("photo");
        context.Response.Write("上传成功");
      }
      else
      {
        context.Response.Write("支持格式：|jpg|gif|bmp|");
      }
    }
    else
    {
      context.Response.Write("你的图片已经超过500K的大小！");
    }
  }