错误:在angular2中没有HttpHandler的提供程序

我试图通过拦截器实现HttpCache.以下是caching-interceptor.service.ts

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

import 'rxjs/add/operator/do';
import 'rxjs/add/observable/of';

export abstract class HttpCache {
  abstract get(req: HttpRequest): HttpResponse|null;
  abstract put(req: HttpRequest, resp: HttpResponse): void;
}



@Injectable()
export class CachingInterceptor implements HttpInterceptor {
    constructor(private cache: HttpCache) {}

    intercept(req: HttpRequest, next: HttpHandler) : Observable> {
        if(req.method !== 'GET'){
            return next.handle(req);
        }

        const cachedRespOnse= this.cache.get(req);

        if(cachedResponse){
            return Observable.of(cachedResponse);
        }

        return next.handle(req).do(event => {
            if(event instanceof HttpResponse){
                this.cache.put(req, event);
            }
        })
    }
}

我从test.service.ts打电话

import { Injectable } from '@angular/core';
import { Headers, Http, Response} from '@angular/http';
import { HttpClient} from '@angular/common/http';
import { Observable } from 'rxjs/Observable';
import { ReplaySubject } from 'rxjs/ReplaySubject';

import 'rxjs/add/operator/map';
import 'rxjs/add/operator/catch';

import { BehaviorSubject } from 'rxjs/BehaviorSubject';

import { APIService } from './api.service';
import { CachingInterceptor } from './caching-interceptor.service';
import { ConfigurationService } from './configuration.service';
import { AuthenticationStatus, IAuthenticationStatus } from '../models';
import { User } from '../models/user.model';

@Injectable()
export class PlatformService extends APIService {



  constructor(private http: Http, public httpClient: HttpClient, private configuration: ConfigurationService,
     public cachingInterceptor: CachingInterceptor) {
    super();


  }

  getUserById(id: string) {
    console.log(this.requestOptions);
    return this.httpClient.get(this._getAPIUrl('user/' + id),this.requestOptions).
      subscribe(res => res);
  }
  get requestOptions(): RequestOptions {
    const tokenObj = window.localStorage.getItem('TOKEN');
    const token = JSON.parse(tokenObj);
    const headers = this.headers;
    headers.append('Authorization', 'Bearer ' + token.token);
    headers.append('Access-Control-Allow-Origin', '*');
    return new RequestOptions({ headers: headers });
  }


}

和模块文件如下

import { CommonModule } from '@angular/common';
import { HTTP_INTERCEPTORS, HttpClient } from '@angular/common/http';
import { FormsModule } from '@angular/forms';

import { ModuleWithProviders, NgModule } from '@angular/core';

import { PlatformService } from '../../services/platform.service';
import { CachingInterceptor } from '../../services/caching-interceptor.service';


@NgModule({
  imports: [CommonModule, FormsModule],

  declarations: [],

  exports: [],

  entryComponents: [EntryHereComponent]
})
export class StructurModule {
  public static forRoot(): ModuleWithProviders {
    return { ngModule: StructurModule, providers: [PlatformService,
       {
        provide: HTTP_INTERCEPTORS,
        useExisting: CachingInterceptor,
        multi: true
    },HttpClient] };
  }
}

我不明白,遗漏了什么,所以它给出了错误

没有HttpHandler的提供者.

如果我在模块文件中的提供程序中添加HttpHandler,它会开始给出提供错误:HTTP_INTERCEPTORS,component.

HttpClient在角4.3的引入,所以如果你想用HttpClient你需要导入HttpClientModule的'@angular/common/http'.确保导入HttpClientModule后BrowserModule如下所示.这个官方文件等 答案将为您提供深入的信息.

import { HttpClientModule } from '@angular/common/http';

@NgModule({
 imports: [
   BrowserModule,
   HttpClientModule
 ],
 ...