SignalR -如何访问其他服务器端类中的用户映射，以便向特定用户发送通知

// 在Startup.cs中配置SignalR
public void ConfigureServices(IServiceCollection services)
{
    services.AddSignalR();
}

public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
    app.UseRouting();

    app.UseEndpoints(endpoints =>
    {
        endpoints.MapHub<MyHub>("/myhub");
    });
}

// 创建一个Hub类
public class MyHub : Hub
{
    public async Task SendMessage(string user, string message)
    {
        // 向特定用户发送通知
        await Clients.User(user).SendAsync("ReceiveMessage", message);
    }
}

// 在其他服务器端类中使用HubContext
public class MyService
{
    private readonly IHubContext<MyHub> _hubContext;

    public MyService(IHubContext<MyHub> hubContext)
    {
        _hubContext = hubContext;
    }

    public async Task SendNotificationToUser(string user, string message)
    {
        // 向特定用户发送通知
        await _hubContext.Clients.User(user).SendAsync("ReceiveNotification", message);
    }
}