Angular 2自动阻止每个http请求的ui

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

@Injectable()
export class LoadingInterceptor implements HttpInterceptor {
  constructor(private loadingService: LoadingService) {}

  intercept(request: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
    this.loadingService.showLoading(); // 显示加载指示器

    return next.handle(request).pipe(
      finalize(() => {
        this.loadingService.hideLoading(); // 隐藏加载指示器
      })
    );
  }
}

import { NgModule } from '@angular/core';
import { HttpClientModule, HTTP_INTERCEPTORS } from '@angular/common/http';

@NgModule({
  imports: [HttpClientModule],
  providers: [
    {
      provide: HTTP_INTERCEPTORS,
      useClass: LoadingInterceptor,
      multi: true
    }
  ]
})
export class AppModule {}