Blazor服务器-如何陷阱Blazor服务器页面关闭事件-选项卡关闭或浏览器关闭-关闭辅助signalR连接

Question

我对Blazor Server还是陌生的，并且已经设法调整默认的.Net核心项目模板来创建自己的index.html页面。

我的index.html页面连接到辅助signalR集线器，以从后端Kafka主题接收一些信息。

使用Blazor Server，如何捕获页面的关闭事件（以响应浏览器选项卡关闭，关闭浏览器或访问另一个链接），以便我可以关闭与辅助signalR集线器的连接？

namespace WebApp.Pages
{
    public partial class Index : ComponentBase, IAsyncDisposable
    {
        private HubConnection hubConnection;
        public bool IsConnected => hubConnection.State == HubConnectionState.Connected;

        [Inject]
        public NavigationManager NavigationManager { get; set; }
        [Inject]
        public IMotionDetectionRepository Repository { get; set; }
        [Inject]
        public ILogger<MotionDetectionConverter> LoggerMotionDetection { get; set; }
        [Inject]
        public ILogger<MotionInfoConverter> LoggerMotionInfo { get; set; }
        [Inject]
        public ILogger<JsonVisitor> LoggerJsonVisitor { get; set; }
        [Inject]
        public ILogger<Index> Logger { get; set; }


        /// <summary>
        /// Dispose of the signalR connection when page disposed
        /// </summary>
        public async ValueTask DisposeAsync()
        {
            if (hubConnection != null)
            {
                Logger.LogInformation("Disposing signalR connection...");
                await hubConnection.DisposeAsync();
            }
        }

        protected override async Task OnInitializedAsync()
        {
            var hubUrl = NavigationManager.BaseUri.TrimEnd('/') + "/motionhub";

            try
            {
                hubConnection = new HubConnectionBuilder()
                    .WithUrl(hubUrl)
                    .ConfigureLogging(logging =>
                    {
                        logging.AddConsole();
                        logging.AddFilter("Microsoft.AspNetCore.SignalR", LogLevel.Information);
                    })
                    .AddJsonProtocol(options =>
                    {
                        options.PayloadSerializerOptions = JsonConvertersFactory.CreateDefaultJsonConverters(LoggerMotionDetection, LoggerMotionInfo, LoggerJsonVisitor);
                    })
                    .Build();

                hubConnection.On<MotionDetection>("ReceiveMotionDetection", ReceiveMessage);
                hubConnection.Closed += CloseHandler;

                await hubConnection.StartAsync();

                Logger.LogInformation("Index Razor Page initialised, listening on signalR hub url => " + hubUrl.ToString());
            }
            catch (Exception e)
            {
                Logger.LogError(e, "Encountered exception => " + e);
            }
        }


        /// <remarks>
        /// If this event was triggered from a connection error, the Exception that occurred will be 
        /// passed in as the sole argument to this handler.
        /// If this event was triggered intentionally by either the client or server, then the argument
        /// will be null.
        /// </remarks>
        private Task CloseHandler(Exception exception)
        {
            if (exception == null)
            {
                Logger.LogInformation("signalR client connection closed");
            }
            else
            {
                Logger.LogInformation($"signalR client closed due to error => {exception.Message}");
            }

            return Task.CompletedTask;
        }

        private void ReceiveMessage(MotionDetection message)
        {
            try
            {
                Logger.LogInformation("Motion detection message received");

                Repository.AddItem(message);

                StateHasChanged();
            }
            catch (Exception ex)
            {
                Logger.LogError(ex, "An exception was encountered => " + ex.ToString());
            }
        }
    }
}