Angular 4 - Observable.do() 的回调未在拦截器中调用

Question

尝试实现在请求进行时显示加载指示器的解决方案。从解决方案来看，我用服务实现了拦截器。一切正常，除了计数器没有减少，因为 .do() 回调永远不会被执行（b 永远不会在控制台中打印）。对此有什么想法吗？如何知道请求是否完成？

import { Injectable } from '@angular/core';
import { HttpEvent, HttpInterceptor, HttpHandler, HttpRequest } from '@angular/common/http';
import { Observable } from 'rxjs/Observable';
import 'rxjs/add/operator/do';

import { LoadingIndicatorService } from './loading-indicator.service';

@Injectable()
export class LoadingIndicatorInterceptor implements HttpInterceptor {
    constructor(private loadingIndicatorService: LoadingIndicatorService) {}

    intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
      this.loadingIndicatorService.requestsCount++;

      const handleObs: Observable<HttpEvent<any>> = next.handle(req);

      console.log('a');
      handleObs.do(() => {
        console.log('b');
        this.loadingIndicatorService.requestsCount--;
      });

      return handleObs;
    }
}

Answer 1

永远不会触发 do() 因为您必须 return 您的新可观察对象。你可以这样做：

export class LoadingIndicatorInterceptor implements HttpInterceptor {
constructor(private loadingIndicatorService: LoadingIndicatorService) {}

intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
  this.loadingIndicatorService.requestsCount++;

  const handleObs: Observable<HttpEvent<any>> = next.handle(req);

  console.log('a');
  return handleObs.do(() => {
    console.log('b');
    this.loadingIndicatorService.requestsCount--;
  });
}
}

Angular 4 - Observable.do() 的回调未在拦截器中调用

Angular 4 - Callback for Observable.do() does not get called in interceptor

interceptor

observable

angular-http-interceptors

angular