I have such code, but applicationContext is null, how I can get in ProcessRequest function current applicationContext ? I need to GetMediaByPath get works

public class FileHandler : IHttpHandler
{

    public FileHandler()
    {

    }

    bool IHttpHandler.IsReusable
    {
        get { return false; }
    }

    void IHttpHandler.ProcessRequest(HttpContext context)
    {
        int protectedMediaFolderId = 1388;


        var applicationContext = Umbraco.Core.ApplicationContext.Current;
        IMedia mediaItem =applicationContext.Services.MediaService.GetMediaByPath(context.Request.FilePath);

        bool isProtected = mediaItem.Path.Split(',').ToList().Contains(protectedMediaFolderId.ToString());

        switch (context.Request.HttpMethod)
        {
            case "GET":
                {
                    // Is the user logged-in? 
                    if (!context.User.Identity.IsAuthenticated)
                    {
                        System.Web.HttpContext.Current.Response.Redirect("/");
                        return;
                    }

                    string requestedFile = context.Server.MapPath(context.Request.FilePath);

                    SendContentTypeAndFile(context, requestedFile);

                    break;
                }
        }
    }


    HttpContext SendContentTypeAndFile(HttpContext context, String strFile)
    {
        context.Response.ContentType = GetContentType(strFile);
        context.Response.TransmitFile(strFile);
        context.Response.End();

        return context;
    }

    public string GetContentType(string filename)
    {
        // used to set the encoding for the reponse stream 
        string res = null;
        FileInfo fileinfo = new FileInfo(filename);

        if (fileinfo.Exists)
        {
            switch (fileinfo.Extension.Remove(0, 1).ToLower())
            {
                case "pdf":
                    {
                        res = "application/pdf";
                        break;
                    }
                case "doc":
                    {
                        res = "application/msword";
                        break;
                    }
                case "docx":
                    {
                        res = "application/vnd.openxmlformats-officedocument.wordprocessingml.document";
                        break;
                    }
                case "xls":
                    {
                        res = "application/vnd.ms-excel";
                        break;
                    }
                case "xlsx":
                    {
                        res = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
                        break;
                    }
                case "mp3":
                    {
                        res = "audio/mpeg";
                        break;
                    }
            }

            return res;
        }

        return null;
    }

}