angular 2.0.1及更高版本有一些改动:

    import {RequestOptions, RequestMethod, Headers} from '@angular/http';
    import { BrowserModule } from '@angular/platform-browser';
    import { HttpModule }     from '@angular/http';
    import { AppRoutingModule } from './app.routing.module';   
    import { AppComponent }  from './app.component';

    //you can move this class to a better place
    class GlobalHttpOptions extends RequestOptions {
        constructor() { 
          super({ 
            method: RequestMethod.Get,
            headers: new Headers({
              'MyHeader': 'MyHeaderValue',
            })
          });
        }
      }

    @NgModule({

      imports:      [ BrowserModule, HttpModule, AppRoutingModule ],
      declarations: [ AppComponent],
      bootstrap:    [ AppComponent ],
      providers:    [ { provide: RequestOptions, useClass: GlobalHttpOptions} ]
    })

    export class AppModule { }

我喜欢覆盖默认选项的想法，这似乎是一个很好的解决方案。

但是，如果您打算扩展Http类。一定要把这篇文章看完!

这里的一些答案实际上显示了request()方法的不正确重载，这可能导致难以捕捉的错误和奇怪的行为。这是我自己偶然发现的。

这个解决方案基于Angular 4.2中的request()方法实现。X，但应该是未来兼容的:

import {Observable} from 'rxjs/Observable';
import {Injectable} from '@angular/core';

import {
  ConnectionBackend, Headers,
  Http as NgHttp,
  Request,
  RequestOptions,
  RequestOptionsArgs,
  Response,
  XHRBackend
} from '@angular/http';


import {AuthenticationStateService} from '../authentication/authentication-state.service';


@Injectable()
export class Http extends NgHttp {

  constructor (
    backend: ConnectionBackend,
    defaultOptions: RequestOptions,
    private authenticationStateService: AuthenticationStateService
  ) {
    super(backend, defaultOptions);
  }


  request (url: string | Request, options?: RequestOptionsArgs): Observable<Response> {

    if ('string' === typeof url) {

      url = this.rewriteUrl(url);
      options = (options || new RequestOptions());
      options.headers = this.updateHeaders(options.headers);

      return super.request(url, options);

    } else if (url instanceof Request) {

      const request = url;
      request.url = this.rewriteUrl(request.url);
      request.headers = this.updateHeaders(request.headers);

      return super.request(request);

    } else {
      throw new Error('First argument must be a url string or Request instance');
    }

  }


  private rewriteUrl (url: string) {
    return environment.backendBaseUrl + url;
  }

  private updateHeaders (headers?: Headers) {

    headers = headers || new Headers();

    // Authenticating the request.
    if (this.authenticationStateService.isAuthenticated() && !headers.has('Authorization')) {
      headers.append('Authorization', 'Bearer ' + this.authenticationStateService.getToken());
    }

    return headers;

  }

}

注意，我是这样导入原始类的:import {Http as NgHttp} from '@angular/ Http ';为了防止名字冲突。

这里要解决的问题是request()方法有两个不同的调用签名。当传递的是Request对象而不是URL字符串时，Angular会忽略options参数。所以这两种情况都必须妥善处理。

下面是如何用DI容器注册这个被重写的类的例子:

export const httpProvider = {
  provide: NgHttp,
  useFactory: httpFactory,
  deps: [XHRBackend, RequestOptions, AuthenticationStateService]
};


export function httpFactory (
  xhrBackend: XHRBackend,
  requestOptions: RequestOptions,
  authenticationStateService: AuthenticationStateService
): Http {
  return new Http(
    xhrBackend,
    requestOptions,
    authenticationStateService
  );
}

使用这种方法，您可以正常地注入Http类，但您的重写类将被神奇地注入。这允许您轻松地集成您的解决方案，而无需更改应用程序的其他部分(操作中的多态性)。

只需将httpProvider添加到模块元数据的providers属性中。

你可以在你的路由中使用canActive，如下所示:

import { Injectable } from '@angular/core';
import { Router } from '@angular/router';
import { CanActivate } from '@angular/router';
import { AuthService } from './auth.service';

@Injectable()
export class AuthGuard implements CanActivate {

  constructor(private auth: AuthService, private router: Router) {}

  canActivate() {
    // If user is not logged in we'll send them to the homepage 
    if (!this.auth.loggedIn()) {
      this.router.navigate(['']);
      return false;
    }
    return true;
  }

}

const appRoutes: Routes = [
  {
    path: '', redirectTo: '/deals', pathMatch: 'full'
  },
  {
    path: 'special',
    component: PrivateDealsComponent,
    /* We'll use the canActivate API and pass in our AuthGuard.
       Now any time the /special route is hit, the AuthGuard will run
       first to make sure the user is logged in before activating and
       loading this route. */
    canActivate: [AuthGuard]
  }
];

摘自:https://auth0.com/blog/angular-2-authentication

这就是我如何为每个请求设置令牌。

import { RequestOptions, BaseRequestOptions, RequestOptionsArgs } from '@angular/http';

export class CustomRequestOptions extends BaseRequestOptions {

    constructor() {
        super();
        this.headers.set('Content-Type', 'application/json');
    }
    merge(options?: RequestOptionsArgs): RequestOptions {
        const token = localStorage.getItem('token');
        const newOptions = super.merge(options);
        if (token) {
            newOptions.headers.set('Authorization', `Bearer ${token}`);
        }

        return newOptions;
    }
}

并在app.module.ts中注册

@NgModule({
    declarations: [
        AppComponent
    ],
    imports: [
        BrowserModule
    ],
    providers: [
        { provide: RequestOptions, useClass: CustomRequestOptions }
    ],
    bootstrap: [AppComponent]
})
export class AppModule { }

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/

像下面这样保持独立的服务怎么样

            import {Injectable} from '@angular/core';
            import {Headers, Http, RequestOptions} from '@angular/http';


            @Injectable()
            export class HttpClientService extends RequestOptions {

                constructor(private requestOptionArgs:RequestOptions) {
                    super();     
                }

                addHeader(headerName: string, headerValue: string ){
                    (this.requestOptionArgs.headers as Headers).set(headerName, headerValue);
                }
            }

当你从另一个地方调用这个时，使用this. httpclientservice。addHeader("Authorization"， " holder " + this.tok);

您将看到添加的标题，例如:-授权如下