Angular SignalR 可以打开多个 WebSocket。在 Angular 中，可以使用 SignalR 的 HubConnectionBuilder 和 HubConnection 类来启动和管理与服务器的 WebSocket 连接。以下是一个示例：

import { Injectable } from '@angular/core';
import * as signalR from '@aspnet/signalr';

@Injectable({
  providedIn: 'root'
})
export class MySignalRService {
  private hubConnection: signalR.HubConnection;

  constructor() { }

  public startConnection() {
    this.hubConnection = new signalR.HubConnectionBuilder()
      .withUrl('/my-hub')
      .build();

    this.hubConnection.start()
      .then(() => console.log('SignalR connection started'))
      .catch(err => console.error('Error while starting SignalR connection: ' + err));
  }

  public stopConnection() {
    this.hubConnection.stop()
      .then(() => console.log('SignalR connection stopped'))
      .catch(err => console.error('Error while stopping SignalR connection: ' + err));
  }

  public addListener(eventName: string, callback: (...args: any[]) => void) {
    this.hubConnection.on(eventName, callback);
  }

  public removeListener(eventName: string, callback: (...args: any[]) => void) {
    this.hubConnection.off(eventName, callback);
  }

  public send(eventName: string, ...args: any[]) {
    this.hubConnection.invoke(eventName, ...args)
      .catch(err => console.error('Error while sending SignalR message: ' + err));
  }
}