import { HttpClientModule } from '@angular/common/http';
@NgModule({
 declarations: [
  AppComponent
 ],
 imports: [
  BrowserModule,
  HttpClientModule
 ],
 bootstrap: [AppComponent]
})
export class AppModule { }

http.get(url).map(res => res.json()).subscribe(...)

http.get(url).subscribe(...)

import {
 HttpRequest,
 HttpHandler,
 HttpEvent
} from '@angular/common/http';

@Injectable()
class JWTInterceptor implements HttpInterceptor {
 
 constructor(private userService: UserService) {}
 
 intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {

  const JWT = `Bearer ${this.userService.getToken()}`;
  req = req.clone({
   setHeaders: {
    Authorization: JWT
   }
  });
  return next.handle(req);
 }
}

export interface HttpInterceptor {
 intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>>;
}

@Injectable()
class JWTInterceptor implements HttpInterceptor {

 constructor(private router: Router) {}
 
 intercept(req: HttpRequest < any > ,
  next: HttpHandler): Observable < HttpEvent < any >> {

  return next.handle(req).map(event => {
    if (event instanceof HttpResponse) {
     if (event.status === 401) {
      // JWT expired, go to login
     }
    }
    return event;
   }
  }
}

[{ provide: HTTP_INTERCEPTORS, useClass: JWTInterceptor, multi: true }]

import {
 HttpEventType,
 HttpClient,
 HttpRequest
} from '@angular/common/http';

http.request(new HttpRequest(
 'POST',
  URL,
  body, 
 {
  reportProgress: true
 })).subscribe(event => {

 if (event.type === HttpEventType.DownloadProgress) {
  // {
  // loaded:11, // Number of bytes uploaded or downloaded.
  // total :11 // Total number of bytes to upload or download
  // }
 }

 if (event.type === HttpEventType.UploadProgress) {
  // {
  // loaded:11, // Number of bytes uploaded or downloaded.
  // total :11 // Total number of bytes to upload or download
  // }
 }

 if (event.type === HttpEventType.Response) {
  console.log(event.body);
 }
})

export enum HttpEventType {
 /**
  * 表示请求已经被发送
  */
 Sent,

 /**
  * 已接收到上传进度事件
  */
 UploadProgress,

 /**
  * 已接收到响应状态码和响应头
  */
 ResponseHeader,

 /**
  * 已接收到下载进度事件
  */
 DownloadProgress,

 /**
  * 已接收全部响应，包含响应体 
  */
 Response,

 /**
  * 用户自定义事件，来自拦截器或后端
  */
 User,
}

describe('HttpClient', () => {
  let client: HttpClient = null !;
  let backend: HttpClientTestingBackend = null !;
  beforeEach(() => {
   backend = new HttpClientTestingBackend();
   client = new HttpClient(backend);
  });
  afterEach(() => { backend.verify(); }); // 请求验证
 
  describe('makes a basic request', () => {
   it('for JSON data', (done: DoneFn) => {
    client.get('/test').subscribe(res => {
     expect((res as any)['data']).toEqual('hello world');
     done();
    });
    backend.expectOne('/test').flush({'data': 'hello world'});
   });
   
   it('for an arraybuffer', (done: DoneFn) => {
    const body = new ArrayBuffer(4);
    // 还支持 {responseType: 'text'}、{responseType: 'blob'}
    client.get('/test', {responseType: 'arraybuffer'}).subscribe(res => {
     expect(res).toBe(body);
     done();
    });
    backend.expectOne('/test').flush(body);
   });
   
   it('that returns a response', (done: DoneFn) => {
    const body = {'data': 'hello world'};
    client.get('/test', {observe: 'response'}).subscribe(res => {
     expect(res instanceof HttpResponse).toBe(true);
     expect(res.body).toBe(body);
     done();
    });
    backend.expectOne('/test').flush(body);
   });
  });
});

describe('makes a POST request', () => {
   it('with text data', (done: DoneFn) => {
    client.post('/test', 'text body', {observe: 'response', responseType: 'text'})
      .subscribe(res => {
       expect(res.ok).toBeTruthy();
       expect(res.status).toBe(200);
       done();
      });
    backend.expectOne('/test').flush('hello world');
   });
 
   it('with json data', (done: DoneFn) => {
    const body = {data: 'json body'};
    client.post('/test', body, {observe: 'response', 
     responseType: 'text'}).subscribe(res => {
     expect(res.ok).toBeTruthy();
     expect(res.status).toBe(200);
     done();
    });
    const testReq = backend.expectOne('/test');
    expect(testReq.request.body).toBe(body);
    testReq.flush('hello world');
   });
});

describe('makes a JSONP request', () => {
   it('with properly set method and callback', (done: DoneFn) => {
    client.jsonp('/test', 'myCallback').subscribe(() => done());
    backend.expectOne({method: 'JSONP', url: '/test?myCallback=JSONP_CALLBACK'})
      .flush('hello world');
   });
});