如何动态覆盖Angular2可注入服务？

我有一个可注入的服务，HttpRequestService，当没有服务器时，我想用MockHttpRequestService替换它，因为我在开发模式（npm start）下运行。此MockHttpRequestService将返回非常简单的响应

我想我已经找到了一种动态替换HttpRequestService的方法，但不幸的是，我看到HttpRequestService仍在使用。以下是我尝试过的：

梅因酒店

import {bootstrap} from '@angular/platform-browser-dynamic';
import {provide} from '@angular/core';
import {ROUTER_PROVIDERS, Router} from '@angular/router-deprecated';
import {HashLocationStrategy, LocationStrategy} from '@angular/common'
import {Http, HTTP_PROVIDERS} from '@angular/http';
import {CORE_DIRECTIVES} from '@angular/common';
import {HttpRequestService} from './app/services/HttpRequestService';
import {MockHttpRequestService} from './app/services/MockHttpRequestService'
import {MyConfigInjectable} from './app/MyConfigInjectable';
import {SomeService} from './app/services/SomeService';

export function main(initialState?: any): Promise<any> {

    let providers = [
        ...HTTP_PROVIDERS,
        ...CORE_DIRECTIVES,
        ...ROUTER_PROVIDERS,
        provide(LocationStrategy, { useClass: HashLocationStrategy })
    ];

    if(process.env.ENV === 'development'){
        console.log('Is it set to development?'); //Yes. Yes it is.
        providers.push(MyConfigInjectable);
        providers.push(SomeService);
        providers.push(provide(HttpRequestService, {
            deps: [MyConfigInjectable, Http, SomeService, Router],
            useClass: MockHttpRequestService
        }));
    }

    return bootstrap(App, providers).catch(err => console.error(err));
}

---

您可以在引导中使用useClass覆盖Angular2服务可注入服务，如下所示：

    import {provide} from '@angular/core';

    const IS_ENV_DEV = true; //Put this constant in your config maybe

    bootstrap(App, [
      provide(RaceService, {useClass: IS_ENV_DEV ? MockHttpRequestService : HttpRequestService})
    ])

或者直接在使用http服务的组件中

@Component({
   selector: 'my-comp',
   providers: [provide(HttpRequestService, {useClass: MockHttpRequestService})],
   template: `<strong>I use a mocked service</strong>`
})
export class MyComponent {

  constructor(private httpRequestService: HttpRequestService) {
    //Faker !
  }
}

@组件({
选择器：“我的公司”，
提供者：[提供（HttpRequestService，{useClass:MockHttpRequestService}]，
模板：`我使用模拟服务`
})
导出类MyComponent{
构造函数（私有httpRequestService:httpRequestService）{
//骗子！
}
}

---

我希望这个回答是有帮助的：）

Oops。非挥发性物质。让它工作起来。我正在覆盖App.ts组件中的新提供程序。一旦我从App.ts组件的提供者中删除了HttpRequestService，并且只在main.ts中声明了它，一切都正常了。除非有人反对，否则我可能会删除这个问题。

@Component({
   selector: 'my-comp',
   providers: [provide(HttpRequestService, {useClass: MockHttpRequestService})],
   template: `<strong>I use a mocked service</strong>`
})
export class MyComponent {

  constructor(private httpRequestService: HttpRequestService) {
    //Faker !
  }
}