角HttpInterceptor等待订阅结果

Question

我正在尝试构建一个HTTP拦截器，等待发送网络请求，直到onlinePipe返回true。我目前面临的问题是，我似乎无法提出一种解决方案，该解决方案需要等待返回网络请求，直到用户重新联机。

import { Injectable } from '@angular/core';
import { HttpInterceptor, HttpEvent, HttpHandler, HttpRequest, } from '@angular/common/http';
import { Observable, BehaviorSubject } from 'rxjs';
import { NetworkStatusService } from '../services/networkStatus.service';

@Injectable()
export class OfflineRequestInterceptor implements HttpInterceptor {
  constructor(
    private networkStatusService: NetworkStatusService,
  ) {
  }

  onlinePipe = this.networkStatusService.Online;

  intercept(request: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {

    const returnedRequest = new BehaviorSubject<Observable<HttpEvent<any>>>(null);

    this.onlinePipe.subscribe((online) => {
      if (online) {
        returnedRequest.next(next.handle(request));
      }
    });

    return returnedRequest.value;
  }
}

如here所述，我可以尝试实现某种mergeMap。不幸的是，在这种情况下，我无法提出类似的解决方案。