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

我设置头的最大问题(在2022年)是HttpHeaders上的append方法返回原始对象的克隆，而没有修改原始对象本身。所以标题。Append ('header'， 'value')不够。我必须重新分配结果或直接在HTTP调用中使用它:

let headers = new HttpHeaders();
headers = headers.append('header', 'value');
this.http.get<any>('https://someulr.com/api/users', { headers });

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.

为了回答你的问题，你可以提供一个服务来包装Angular的原始Http对象。如下所述。

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

@Injectable()
export class HttpClient {

  constructor(private http: Http) {}

  createAuthorizationHeader(headers: Headers) {
    headers.append('Authorization', 'Basic ' +
      btoa('username:password')); 
  }

  get(url) {
    let headers = new Headers();
    this.createAuthorizationHeader(headers);
    return this.http.get(url, {
      headers: headers
    });
  }

  post(url, data) {
    let headers = new Headers();
    this.createAuthorizationHeader(headers);
    return this.http.post(url, data, {
      headers: headers
    });
  }
}

而不是注入Http对象，你可以注入这个对象(HttpClient)。

import { HttpClient } from './http-client';

export class MyComponent {
  // Notice we inject "our" HttpClient here, naming it Http so it's easier
  constructor(http: HttpClient) {
    this.http = httpClient;
  }

  handleSomething() {
    this.http.post(url, data).subscribe(result => {
        // console.log( result );
    });
  }
}

我还认为可以通过提供自己的类来扩展Http类，从而为Http类使用多个提供者……请看这个链接:http://blog.thoughtram.io/angular2/2015/11/23/multi-providers-in-angular-2.html。

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]
})

对于Angular 5及以上版本，我们可以使用HttpInterceptor泛化请求和响应操作。 这有助于我们避免重复:

1)通用报头

2)指定响应类型

3)查询请求

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

@Injectable()
export class AuthHttpInterceptor implements HttpInterceptor {

  requestCounter: number = 0;
  constructor() {
  }

  intercept(request: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {

    request = request.clone({
      responseType: 'json',
      setHeaders: {
        Authorization: `Bearer token_value`,
        'Content-Type': 'application/x-www-form-urlencoded; charset=UTF-8'
      }
    });

    return next.handle(request).do((event: HttpEvent<any>) => {
      if (event instanceof HttpResponse) {
        // do stuff with response if you want
      }
    }, (err: any) => {
      if (err instanceof HttpErrorResponse) {
        // do stuff with response error if you want
      }
    });
  }
}

我们可以使用这个AuthHttpInterceptor类作为HttpInterceptors的提供者:

import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
import { AppComponent } from './app.component';
import { AppRoutingModule } from './app.routing-module';
import { AuthHttpInterceptor } from './services/auth-http.interceptor';
import { HttpClientModule, HTTP_INTERCEPTORS } from '@angular/common/http';
import { BrowserAnimationsModule } from '@angular/platform-browser/animations';

@NgModule({
  declarations: [
    AppComponent
  ],
  imports: [
    BrowserModule,
    AppRoutingModule,
    HttpClientModule,
    BrowserAnimationsModule,
  ],
  providers: [
    {
      provide: HTTP_INTERCEPTORS,
      useClass: AuthHttpInterceptor,
      multi: true
    }
  ],
  exports: [],
  bootstrap: [AppComponent]
})
export class AppModule {
}