angular-cn/packages/common/http/src/interceptor.ts

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/**
* @license
* Copyright Google Inc. All Rights Reserved.
*
* Use of this source code is governed by an MIT-style license that can be
* found in the LICENSE file at https://angular.io/license
*/
import {Injectable, InjectionToken} from '@angular/core';
import {Observable} from 'rxjs';
import {HttpHandler} from './backend';
import {HttpRequest} from './request';
import {HttpEvent} from './response';
/**
* Intercepts `HttpRequest` and handles them.
*
* Most interceptors will transform the outgoing request before passing it to the
* next interceptor in the chain, by calling `next.handle(transformedReq)`.
*
* In rare cases, interceptors may wish to completely handle a request themselves,
* and not delegate to the remainder of the chain. This behavior is allowed.
*
* @publicApi
*/
export interface HttpInterceptor {
/**
* Intercept an outgoing `HttpRequest` and optionally transform it or the
* response.
*
* Typically an interceptor will transform the outgoing request before returning
* `next.handle(transformedReq)`. An interceptor may choose to transform the
* response event stream as well, by applying additional Rx operators on the stream
* returned by `next.handle()`.
*
* More rarely, an interceptor may choose to completely handle the request itself,
* and compose a new event stream instead of invoking `next.handle()`. This is
* acceptable behavior, but keep in mind further interceptors will be skipped entirely.
*
* It is also rare but valid for an interceptor to return multiple responses on the
* event stream for a single request.
*/
intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>>;
}
/**
* `HttpHandler` which applies an `HttpInterceptor` to an `HttpRequest`.
*
*
*/
export class HttpInterceptorHandler implements HttpHandler {
constructor(private next: HttpHandler, private interceptor: HttpInterceptor) {}
handle(req: HttpRequest<any>): Observable<HttpEvent<any>> {
return this.interceptor.intercept(req, this.next);
}
}
/**
* A multi-provider token which represents the array of `HttpInterceptor`s that
* are registered.
*
* @publicApi
*/
export const HTTP_INTERCEPTORS = new InjectionToken<HttpInterceptor[]>('HTTP_INTERCEPTORS');
@Injectable()
export class NoopInterceptor implements HttpInterceptor {
intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
return next.handle(req);
}
}