Reactjs React .NET 使用 signalR 获取所有活动连接的数量

我正在try 与我的react应用程序建立信号器连接，我已经在asp中创建了中心.net核心，但它似乎不会在我的前端工作.

说到信号器，我是新手，但我以前用asp.net核心的MVC应用程序，所以我知道它的逻辑工作.

但我从来没有用React处理过信号器.这就是我需要帮助的原因.

让我给你看一些代码

public class OnConnectionHub : Hub
    {
        public static int ConnectionCount { get; set; }

        public override Task OnConnectedAsync()
        {
            ConnectionCount++;
            Clients.All.SendAsync("updateConnectionCount", ConnectionCount).GetAwaiter().GetResult();
            return base.OnConnectedAsync();
        }

        public override Task OnDisconnectedAsync(Exception? exception)
        {
            ConnectionCount--;
            Clients.All.SendAsync("updateConnectionCount", ConnectionCount).GetAwaiter().GetResult();
            return base.OnDisconnectedAsync(exception);
        }
    }

相当简单，只需在OnConnectedAsync和OnDisconnectedAsync上递增和递减

这是我创建的中心url

endpoints.MapHub<OnConnectionHub>("hubs/onConnectionHub");

这是我的react组件中的一些代码

import { HubConnectionBuilder } from "@microsoft/signalr"
import { useState } from "react"

export const ConnectionCount = () => {
    const [connectionCount, setConnectionCount] = useState(0)
    // create connection
    const connection = new HubConnectionBuilder()
        .withUrl("https://localhost:7199/hubs/onConnectionHub")
        .build()

    // connect to method that hub invokes
    connection.on("updateConnectionCount", (onConnection) => {
        setConnectionCount(onConnection)
        }
    )

    // start connection
    connection.start();

    return <p>Active members {connectionCount}</p>
}

我得到的错误

react_devtools_backend.js:4026 [2022-07-14T08:31:46.444Z] Error: Failed to complete negotiation with the server: TypeError: Failed to fetch
client.onmessage @ WebSocketClient.js:50
2HttpConnection.ts:350 Uncaught (in promise) Error: Failed to complete negotiation with the server: TypeError: Failed to fetch
    at HttpConnection._getNegotiationResponse (HttpConnection.ts:350:1)
    at async HttpConnection._startInternal (HttpConnection.ts:247:1)
    at async HttpConnection.start (HttpConnection.ts:138:1)
    at async HubConnection._startInternal (HubConnection.ts:206:1)
    at async HubConnection._startWithStateTransitions (HubConnection.ts:180:1)

谢谢