Angular4阻断器变化响应

Question

我有一个特别的HttpInterceptor

import {HttpErrorResponse, HttpEvent, HttpHandler, HttpInterceptor, 
HttpRequest} from '@angular/common/http';
import {AuthService} from '../service/auth.service';
import {Observable} from 'rxjs/Observable';
import {Injectable} from '@angular/core';
import {Router} from '@angular/router';

@Injectable()
export class AuthInterceptor implements HttpInterceptor {
  constructor(private authService: AuthService,
              private router: Router) {
  }

  intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
    const authHeader = this.authService.getToken();
    const clone = req.clone({headers: req.headers.set('Authorization',authHeader)});
    return next.handle(clone).do(() => {
}, err => {
  console.log(err);
  if (err instanceof HttpErrorResponse && err.status === 401) {
    this.authService.clearToken();
    this.router.navigate(['/auth/signin']);
    return Observable.empty();
      }
    });
  }
}

这个拦截器工作得很好，但是当我得到401时，我将用户重定向到登录页面，但是错误仍然会传递给服务，而在该服务中，我显示的是错误msg，这个msg显示在signin页面上。因此，我希望在if (err instanceof HttpErrorResponse && err.status === 401) {块中更改响应或执行一些操作，以便在本例中不返回错误。

return Observable.empty();

没有用

Answer 1

next.handle(clone).do() -这就是导致这种行为的原因。do()操作符只打算提供副作用，但实际上并不会影响数据流和可观察管道中的错误处理。本质上，它是说“当这种情况发生时，请做这个和那个，然后继续，就好像根本没有do()节一样”。如果您想要抑制错误，那么您需要使用catch()运算符。

代码将几乎相同：

@Injectable()
export class AuthInterceptor implements HttpInterceptor {
    constructor(private authService: AuthService,
                private router: Router) {
    }

    intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
        const authHeader = this.authService.getToken();
        const clone = req.clone({headers: req.headers.set('Authorization',authHeader)});
        return next.handle(clone).catch(err => { // <-- here
            console.log(err);
            if (err instanceof HttpErrorResponse && err.status === 401) {
                this.authService.clearToken();
                this.router.navigate(['/auth/signin']);
                return Observable.empty();
            }
            // we must tell Rx what to do in this case too
            return Observable.throw(err);
        });
    }
}