扩展 http 类并访问自定义属性（Angular2 typescript）

Question

我创建了 CustomHttp 类，它像这里一样扩展 Http：http://restlet.com/blog/2016/04/18/interacting-efficiently-with-a-restful-service-with-angular2-and-rxjs-part-3/#comment-83563

我像这样将提供程序添加到引导程序中：

bootstrap([
    HTTP_PROVIDERS,
    { provide:Http,
        useFactory: (backend: XHRBackend, defaultOptions: RequestOptions, errorNotifier: NotificationHandlerService, 
                     authService: AuthInfoService) => {
            return new CustomHttp(backend, defaultOptions, errorNotifier, authService);
        },
        deps: [ XHRBackend, RequestOptions, NotificationHandlerService,  AuthInfoService]
    },
  ])

所有被覆盖的方法（get、post 等）都可以正常工作。然后我将自定义属性和方法添加到 CustomHttp 类并尝试访问 CustomHttp 之外的属性：

@Injectable()
export class CustomHttp extends Http {

...
private myCustomProperty = 'It`s custom';

public getCustomProperty() {
    return this.myCustomProperty;
}
...

}

======================

import {Http} from '@angular/http';

export class MainComponent {

    constructor(private _http: Http) {
       this._http.getCustomProperty(); // this method doesn`t exist in Http
    }
}

如何访问 CustomHttp 的自定义方法和属性？

Answer 1

您可以通过将 Http 实例强制转换为 CustomHttp 来尝试以下操作：

import { Injectable } from '@angular/core';
import { Http } from '@angular/http';
import { CustomHttp } from './custom.http';

@Injectable()
export class BooksService {

  constructor(private http:Http) {
    console.log((<CustomHttp>this.http).someProperty);
  }

  (...)
}

使用以下CustomHttp 类：

@Injectable()
export class CustomHttp extends Http {
  someProperty:string = 'some string';

  (...)
}

Answer 2

import {Http} from '@angular/http';
import {CustomHttp} from '/path';

export class MainComponent {

    constructor(private _http: CustomHttp) {
       this._http.getCustomProperty(); 
    }
}