c# - 如何使用带有 .NET Core 的 SignalR 从集线器类使用服务器端计时器？

Question

我想在 .NET Core 项目中使用 SignalR 从服务器端应用计时器。我可以使用自定义类启动计时器。计时器应在单击停止按钮时停止，并在单击开始按钮时启动。这只是我正在创建的一个演示，就像开始和停止 watch 一样。

我已经使用 Node.js 实现了相同的功能，我没有遇到任何问题。在带有 .NET Core 的 SignalR 中，只是我无法得到相同的结果。

// Custom Timer class to be able to access HubCallerContext and Clients
public class CustomTimer : System.Timers.Timer
{
    public CustomTimer(double interval)
        : base(interval)
    {
    }

    public HubCallerContext callerContext { get; set; }
    public IHubCallerClients<IClient> hubCallerClients { get; set; }
}

public class ApplicationHub : Hub<IClient>
{
    public CustomTimer timer = new CustomTimer(1000);

    // This method will be called on Start button click
    public async Task StartTime()
    { 
        timer.callerContext = Context;
        timer.hubCallerClients = Clients;
        timer.Elapsed += aTimer_Elapsed;
        timer.Interval = 1000;
        timer.Enabled = true;
    }

    // This method will pass time to all connected clients
    void aTimer_Elapsed(object sender, System.Timers.ElapsedEventArgs e)
    {
        timer = (CustomTimer)sender;
        HubCallerContext hcallerContext = timer.callerContext;
        IHubCallerClients<IClient> hubClients = timer.hubCallerClients;

        hubClients.Clients.All.ShowTime(DateTime.Now.Hour.ToString() +
            ":" + DateTime.Now.Minute.ToString() + ":" +
            DateTime.Now.Second.ToString());
    }

    // This should stop running timer on button click event from client
    public async Task StopTime()
    {
        timer.Elapsed -= aTimer_Elapsed;
        timer.Enabled = false;

        await Clients.All.StopTime("Timer Stopped");
    }
}

打电话时 StopTimer来自客户端的方法，我没有得到当前的计时器。如果有人能指导我这一点，我将不胜感激。

谢谢
编码意味着问题意味着乐趣。 :)

Answer 1

存储对 timer 的引用在 static ConcurrentDictionary由 ConnectionId 索引.

您只需要添加 3 行并更改 2 行。

public class CustomTimer : System.Timers.Timer
{
    // Add this ↓
    public static ConcurrentDictionary<string, CustomTimer> Timers = new ConcurrentDictionary<string, CustomTimer>();

    // ...
}

public class ApplicationHub : Hub<IClient>
{
    public CustomTimer timer = new CustomTimer(1000);

    // Change this ↓ to `static`, so that `timer.Elapsed -= aTimer_Elapsed;` works
    static void aTimer_Elapsed(object sender, System.Timers.ElapsedEventArgs e)
    {
        // Change this ↓ to `var`
        var timer = (CustomTimer)sender;

        // ...
    }

    public async Task StartTime()
    {
        // Add this ↓
        timer = CustomTimer.Timers.GetOrAdd(Context.ConnectionId, timer);

        // ...
    }

    public async Task StopTime()
    {
        // Add this ↓
        timer = CustomTimer.Timers.GetOrAdd(Context.ConnectionId, timer);

        // ...
    }
}