IIS 8.0 中的 SignalR HttpContext.Current null

Question

我修改了 SignalR 网站文档中的广播示例，而不是随机值，而是读取随机 xml 文件。我正在使用HttpContext.Current.Server.MapPath 方法来访问文件并避免对物理路径进行硬编码。这在 Windows 7 IIS 7.5 和 Visual Studio 2013 中运行良好，但在 Windows 8.1 和 Windows Server 2012 中我发现HttpContext.Current 是null。在提问之前，我搜索了其他问题，但没有找到类似这里发生的任何事情。

这是整个类的代码：

using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Threading;

using Microsoft.AspNet.SignalR;
using Microsoft.AspNet.SignalR.Hubs;

namespace SignalRDisplayXML
{
    public struct ReturnDataScheme
    {
        public List<VsDisplaySlotBean> slotsdata;
        public string filename;
    }

    public class XmlTicker
    {
        private readonly static Lazy<XmlTicker> _instance =
            new Lazy<XmlTicker>(() => new XmlTicker(GlobalHost.ConnectionManager.GetHubContext<DisplayXMLHub>().Clients, HttpContext.Current.Server.MapPath("~/Data/")));

        private DAO _dao = new DAO();
        private ReturnDataScheme _server_data = new ReturnDataScheme();

        private string _directoryPath = string.Empty;

        private readonly object _processRandomXMLLock = new object();
        private volatile bool _updatingRandomXML = false;
        private readonly Timer _timer;

        private XmlTicker(IHubConnectionContext clients, string path)
        {
            Clients = clients;
            _directoryPath = path;

            _server_data.filename = GetRandomFileName();
            _server_data.slotsdata = _dao.GetVesselAll(_server_data.filename);

            _timer = new Timer(ProcessRandomXML, null, 10000, 10000);
        }

        public static XmlTicker Instance
        {
            get
            {
                return _instance.Value;
            }
        }

        private IHubConnectionContext Clients
        {
            get;
            set;
        }

        public ReturnDataScheme GetCurrentData()
        {
            return _server_data;
        }

        private void ProcessRandomXML(object state)
        {
            lock (_processRandomXMLLock)
            {
                if (!_updatingRandomXML)
                {
                    _updatingRandomXML = true;

                    _server_data.filename = GetRandomFileName();
                    _server_data.slotsdata = _dao.GetVesselAll(_server_data.filename);

                    Clients.All.DataPush(_server_data);

                    _updatingRandomXML = false;
                }
            }
        }

        private string GetRandomFileName()
        {
            Random randomizer = new Random(DateTime.Now.Millisecond);
            return _directoryPath + "DisplaySlotFDMF00" + randomizer.Next(1, 9).ToString() + ".xml";
        }
    }
}

谢谢。

Answer 1

您可以使用 HostingEnvironment.MapPath 而不是 HttpContext.MapPath。