c# - 如何在Blazor服务器端的CircuitHandler中调用方法？

我猜这应该可以工作;）

CircuitHandlerService.cs

using Microsoft.AspNetCore.Components.Server.Circuits;
using System;
using System.Collections.Concurrent;
using System.Threading;
using System.Threading.Tasks;


namespace BlazorCircuitHandler.Services
{
    public class CircuitHandlerService : CircuitHandler
    {
        public ConcurrentDictionary<string, Circuit> Circuits { get; 
            set; }
        public event EventHandler CircuitsChanged;

        protected virtual void OnCircuitsChanged()
             => CircuitsChanged?.Invoke(this, EventArgs.Empty);

        public CircuitHandlerService()
        {
             Circuits = new ConcurrentDictionary<string, Circuit>();
        }

        public override Task OnCircuitOpenedAsync(Circuit circuit, 
                             CancellationToken cancellationToken)
       {
             Circuits[circuit.Id] = circuit;
             OnCircuitsChanged();
             return base.OnCircuitOpenedAsync(circuit, 
                                   cancellationToken);
       }

       public override Task OnCircuitClosedAsync(Circuit circuit, 
                 CancellationToken cancellationToken)
      {
           Circuit circuitRemoved;
           Circuits.TryRemove(circuit.Id, out circuitRemoved);
           OnCircuitsChanged();
           return base.OnCircuitClosedAsync(circuit, 
                             cancellationToken);
      }

      public override Task OnConnectionDownAsync(Circuit circuit, 
                            CancellationToken cancellationToken)
      {
          return base.OnConnectionDownAsync(circuit, 
                           cancellationToken);
      }

      public override Task OnConnectionUpAsync(Circuit circuit, 
                          CancellationToken cancellationToken)
      {
          return base.OnConnectionUpAsync(circuit, cancellationToken);
      }
   }
 }

用法

@page "/"

@using Microsoft.AspNetCore.Components.Server.Circuits
@using BlazorCircuitHandler.Services

@inject CircuitHandler circuitHandler
@implements IDisposable



<h1>Hello, world!</h1>

Welcome to your new app.

<p>
 Number of Circuits: @((circuitHandler as 
 BlazorCircuitHandler.Services.CircuitHandlerService).Circuits.Count)
 <ul>
    @foreach (var circuit in (circuitHandler as 
     BlazorCircuitHandler.Services.CircuitHandlerService).Circuits)
    {
        <li>@circuit.Key</li>
    }
 </ul>
</p>

@code {
   protected override void OnInitialized()
   {
       // Subscribe to the event handler
    (circuitHandler as CircuitHandlerService).CircuitsChanged += 
         HandleCircuitsChanged;

    }

 public void Dispose()
 {
    // Unsubscribe the event handler when the component is disposed
    (circuitHandler as CircuitHandlerService).CircuitsChanged -= 
      HandleCircuitsChanged;

 }

 public void HandleCircuitsChanged(object sender, EventArgs args)
 {
    // notify the component that its state has changed 
    // Important: You must use InvokeAsync
    InvokeAsync(() => StateHasChanged());
 }
}

注意：要验证其是否正常运行，请运行该应用程序。然后打开另外两个标签。现在，关闭打开的第一个选项卡（从左到右），然后关闭第二个选项卡。注意显示的活动电路数...