虽然我回答这个问题很晚，但如果有人在寻求更简单的解决方案。

我们可以用angular -jwt。angular2-jwt在从Angular 2应用中发起HTTP请求时，会自动将一个JSON Web令牌(JWT)作为授权标头。

我们可以用高级配置选项设置全局标头

export function authHttpServiceFactory(http: Http, options: RequestOptions) {
  return new AuthHttp(new AuthConfig({
    tokenName: 'token',
        tokenGetter: (() => sessionStorage.getItem('token')),
        globalHeaders: [{'Content-Type':'application/json'}],
    }), http, options);
}

发送每个请求令牌

    getThing() {
  let myHeader = new Headers();
  myHeader.append('Content-Type', 'application/json');

  this.authHttp.get('http://example.com/api/thing', { headers: myHeader })
    .subscribe(
      data => this.thing = data,
      err => console.log(error),
      () => console.log('Request Complete')
    );

  // Pass it after the body in a POST request
  this.authHttp.post('http://example.com/api/thing', 'post body', { headers: myHeader })
    .subscribe(
      data => this.thing = data,
      err => console.log(error),
      () => console.log('Request Complete')
    );
}

通过扩展Angular 2的Http Provider来创建一个自定义Http类，并简单地覆盖自定义Http类中的构造函数和请求方法。下面的例子在每个http请求中添加授权头。

import {Injectable} from '@angular/core';
import {Http, XHRBackend, RequestOptions, Request, RequestOptionsArgs, Response, Headers} from '@angular/http';
import {Observable} from 'rxjs/Observable';
import 'rxjs/add/operator/map';
import 'rxjs/add/operator/catch';

@Injectable()
export class HttpService extends Http {

  constructor (backend: XHRBackend, options: RequestOptions) {
    let token = localStorage.getItem('auth_token'); // your custom token getter function here
    options.headers.set('Authorization', `Bearer ${token}`);
    super(backend, options);
  }

  request(url: string|Request, options?: RequestOptionsArgs): Observable<Response> {
    let token = localStorage.getItem('auth_token');
    if (typeof url === 'string') { // meaning we have to add the token to the options, not in url
      if (!options) {
        // let's make option object
        options = {headers: new Headers()};
      }
      options.headers.set('Authorization', `Bearer ${token}`);
    } else {
    // we have to add the token to the url object
      url.headers.set('Authorization', `Bearer ${token}`);
    }
    return super.request(url, options).catch(this.catchAuthError(this));
  }

  private catchAuthError (self: HttpService) {
    // we have to pass HttpService's own instance here as `self`
    return (res: Response) => {
      console.log(res);
      if (res.status === 401 || res.status === 403) {
        // if not authenticated
        console.log(res);
      }
      return Observable.throw(res);
    };
  }
}

然后配置你的主app.module.ts来提供XHRBackend作为ConnectionBackend提供者，并将RequestOptions提供给你的自定义Http类:

import { HttpModule, RequestOptions, XHRBackend } from '@angular/http';
import { HttpService } from './services/http.service';
...
@NgModule({
  imports: [..],
  providers: [
    {
      provide: HttpService,
      useFactory: (backend: XHRBackend, options: RequestOptions) => {
        return new HttpService(backend, options);
      },
      deps: [XHRBackend, RequestOptions]
    }
  ],
  bootstrap: [ AppComponent ]
})

在此之后，现在可以在服务中使用自定义http提供程序。例如:

import { Injectable }     from '@angular/core';
import {HttpService} from './http.service';

@Injectable()
class UserService {
  constructor (private http: HttpService) {}

  // token will added automatically to get request header
  getUser (id: number) {
    return this.http.get(`/users/${id}`).map((res) => {
      return res.json();
    } );
  }
}

这里有一个全面的指南- http://adonespitogo.com/articles/angular-2-extending-http-provider/

从Angular 4.3开始，HTTP拦截器现在可以通过新的HttpClient @angular/common/ HTTP使用了。X版本及更高版本。

现在为每个请求添加头文件非常简单:

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

@Injectable()
export class AddHeaderInterceptor implements HttpInterceptor {
  intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
    // Clone the request to add the new header
    const clonedRequest = req.clone({ headers: req.headers.append('Authorization', 'Bearer 123') });

    // Pass the cloned request instead of the original request to the next handle
    return next.handle(clonedRequest);
  }
}

有一个不可变性的原则，这就是为什么在设置新内容之前需要克隆请求。

由于编辑头部是一个非常常见的任务，实际上有一个快捷方式(在克隆请求时):

const clonedRequest = req.clone({ setHeaders: { Authorization: 'Bearer 123' } });

创建拦截器之后，你应该使用HTTP_INTERCEPTORS提供的方法注册它。

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

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

在这种情况下，扩展BaseRequestOptions可能会有很大帮助。看看下面的代码:

import {provide} from 'angular2/core';
import {bootstrap} from 'angular2/platform/browser';
import {HTTP_PROVIDERS, Headers, Http, BaseRequestOptions} from 'angular2/http';

import {AppCmp} from './components/app/app';


class MyRequestOptions extends BaseRequestOptions {
  constructor () {
    super();
    this.headers.append('My-Custom-Header','MyCustomHeaderValue');
  }
} 

bootstrap(AppCmp, [
  ROUTER_PROVIDERS,
  HTTP_PROVIDERS,
  provide(RequestOptions, { useClass: MyRequestOptions })
]);

这应该包括'My-Custom-Header'在每个调用。

更新:

为了能够在任何时候改变头，而不是上面的代码，你也可以使用下面的代码来添加一个新的头:

this.http._defaultOptions.headers.append('Authorization', 'token');

要删除就可以了

this.http._defaultOptions.headers.delete('Authorization');

还有另一个函数，你可以用来设置值:

this.http._defaultOptions.headers.set('Authorization', 'token');

上述解决方案在typescript上下文中仍然不完全有效。_defaultHeaders是受保护的，不应该这样使用。我会推荐上面的解决方案作为快速修复，但从长远来看，更好的方法是编写自己的包装器来处理http调用，它也可以处理身份验证。以auth0为例，它更好、更简洁。

https://github.com/auth0/angular2-jwt/blob/master/angular2-jwt.ts

Update - June 2018 I see a lot of people going for this solution but I would advise otherwise. Appending header globally will send auth token to every api call going out from your app. So the api calls going to third party plugins like intercom or zendesk or any other api will also carry your authorization header. This might result into a big security flaw. So instead, use interceptor globally but check manually if the outgoing call is towards your server's api endpoint or not and then attach auth header.

虽然我很晚才回，但也许能帮到别人。当使用@NgModule时，要向所有请求注入头文件，可以这样做:

(我在Angular 2.0.1中进行了测试)

/**
 * Extending BaseRequestOptions to inject common headers to all requests.
 */
class CustomRequestOptions extends BaseRequestOptions {
    constructor() {
        super();
        this.headers.append('Authorization', 'my-token');
        this.headers.append('foo', 'bar');
    }
}

现在在@NgModule中执行以下操作:

@NgModule({
    declarations: [FooComponent],
    imports     : [

        // Angular modules
        BrowserModule,
        HttpModule,         // This is required

        /* other modules */
    ],
    providers   : [
        {provide: LocationStrategy, useClass: HashLocationStrategy},
        // This is the main part. We are telling Angular to provide an instance of
        // CustomRequestOptions whenever someone injects RequestOptions
        {provide: RequestOptions, useClass: CustomRequestOptions}
    ],
    bootstrap   : [AppComponent]
})

在Angular 2.1.2中，我通过扩展Angular Http来解决这个问题:

import {Injectable} from "@angular/core";
import {Http, Headers, RequestOptionsArgs, Request, Response, ConnectionBackend, RequestOptions} from "@angular/http";
import {Observable} from 'rxjs/Observable';

@Injectable()
export class HttpClient extends Http {

  constructor(protected _backend: ConnectionBackend, protected _defaultOptions: RequestOptions) {

    super(_backend, _defaultOptions);
  }

  _setCustomHeaders(options?: RequestOptionsArgs):RequestOptionsArgs{
    if(!options) {
      options = new RequestOptions({});
    }
    if(localStorage.getItem("id_token")) {

      if (!options.headers) {

        options.headers = new Headers();


      }
      options.headers.set("Authorization", localStorage.getItem("id_token"))
    }
    return options;
  }


  request(url: string|Request, options?: RequestOptionsArgs): Observable<Response> {
    options = this._setCustomHeaders(options);
    return super.request(url, options)
  }
}

然后在我的应用程序提供者中，我可以使用自定义工厂来提供“Http”

import { RequestOptions, Http, XHRBackend} from '@angular/http';
import {HttpClient} from './httpClient';
import { RequestOptions, Http, XHRBackend} from '@angular/http';
import {HttpClient} from './httpClient';//above snippet

function httpClientFactory(xhrBackend: XHRBackend, requestOptions: RequestOptions): Http {
  return new HttpClient(xhrBackend, requestOptions);
}

@NgModule({
  imports:[
    FormsModule,
    BrowserModule,
  ],
  declarations: APP_DECLARATIONS,
  bootstrap:[AppComponent],
  providers:[
     { provide: Http, useFactory: httpClientFactory, deps: [XHRBackend, RequestOptions]}
  ],
})
export class AppModule {
  constructor(){

  }
}

现在我不需要声明每个Http方法，可以在整个应用程序中正常使用Http。