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 });

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。

经过一些调查，我发现最后也是最简单的方法是扩展我喜欢的BaseRequestOptions。 以下是我尝试过但由于某些原因放弃的方法: 1. 扩展BaseRequestOptions，并在constructor()中添加动态头。如果我登录，它不能工作。它只创建一次。所以它不是动态的。 2. 扩展Http。与上面的原因相同，我不能在构造函数()中添加动态头文件。如果我重写request(..)方法，并设置报头，像这样:

request(url: string|Request, options?: RequestOptionsArgs): Observable<Response> {
 let token = localStorage.getItem(AppConstants.tokenName);
 if (typeof url === 'string') { // meaning we have to add the token to the options, not in url
  if (!options) {
    options = new RequestOptions({});
  }
  options.headers.set('Authorization', 'token_value');
 } else {
  url.headers.set('Authorization', 'token_value');
 }
 return super.request(url, options).catch(this.catchAuthError(this));
}

你只需要重写这个方法，而不是重写所有的get/post/put方法。

3.我的首选解决方案是扩展BaseRequestOptions和覆盖merge():

@Injectable()
export class AuthRequestOptions extends BaseRequestOptions {

 merge(options?: RequestOptionsArgs): RequestOptions {
  var newOptions = super.merge(options);
  let token = localStorage.getItem(AppConstants.tokenName);
  newOptions.headers.set(AppConstants.authHeaderName, token);
  return newOptions;
 }
}

这个merge()函数将被每个请求调用。

最简单的

创建配置。ts文件

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

export class Config {
    url: string = 'http://localhost:3000';
    httpOptions: any = {
        headers: new HttpHeaders({
           'Content-Type': 'application/json',
           'Authorization': JSON.parse(localStorage.getItem('currentUser')).token
        })
    }
}

然后在你的服务上，导入配置。ts文件

import { Config } from '../config';
import { HttpClient } from '@angular/common/http';

@Injectable()
export class OrganizationService {
  config = new Config;

  constructor(
    private http: HttpClient
  ) { }

  addData(data): Observable<any> {
     let sendAddLink = `${this.config.url}/api/addData`;

     return this.http.post(sendAddLink , data, this.config.httpOptions).pipe(
       tap(snap => {
      return snap;
        })
    );
 } 

我认为这是最简单和最安全的。

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]
})

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 {}