Angular 2 RC 5 Bootstrap自定义HTTP类TypeError：无法读取属性

使用RC 4,我可以在bootstrap中使用它,没有任何问题使用下面的代码：

bootstrap(AppComponent,[
    HTTP_PROVIDERS,provide(RequestOptions,{ useClass: DefaultRequestOptions }),provide(Http,{
        useFactory: (backend: XHRBackend,defaultOptions: RequestOptions) => new HttpLoading(backend,defaultOptions),deps: [XHRBackend,RequestOptions]
    })
]).catch(err => console.error(err));

我的DefaultRequest选项类

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

@Injectable()
export class DefaultRequestOptions extends BaseRequestOptions {
    headers: Headers = new Headers({
        'Content-Type': 'application/json'
    });
}

我的HttpLoading类看起来像这样：

import { Http,RequestOptionsArgs,ConnectionBackend,RequestOptions,Response } from '@angular/http'
import { Injectable } from '@angular/core'
import {GlobalService} from './globalService';
import { Observable } from 'rxjs/Observable';

export class HttpLoading extends Http {

    constructor(backend: ConnectionBackend,defaultOptions: RequestOptions,private _globalService: GlobalService) {
        super(backend,defaultOptions);
    }

    get(url: string,options?: RequestOptionsArgs): Observable<any> {
        this._globalService.isLoading = true;
        return super.get(url,options)
            .map(res => {
                this._globalService.isLoading = false;
                return res.json();
            })
            .catch(this.handleError);
    }
}

使用角度2 RC 5,引导方式已经改变,我们现在需要有NgModule和bootstrap.我已经遵循迁移指南,并在NgModule下创建了我：

import { NgModule }       from '@angular/core';
import { BrowserModule  } from '@angular/platform-browser';
import { FormsModule,ReactiveFormsModule }   from '@angular/forms';
import { HttpModule }     from '@angular/http';
import { Http,HTTP_PROVIDERS,XHRBackend } from '@angular/http';

import { DefaultRequestOptions } from './DefaultRequestOptions';
import { HttpLoading } from './http-loading';

import { routing }        from './app.routing';
import { AppComponent } from './components/app.component';


@NgModule({
    imports: [
        BrowserModule,FormsModule,ReactiveFormsModule,HttpModule,routing
    ],declarations: [
        AppComponent
    ],providers: [
        HTTP_PROVIDERS,{ provide: RequestOptions,useClass: DefaultRequestOptions },{
            provide: Http,useFactory: (backend: XHRBackend,globalService: GlobalService) => new HttpLoading(backend,defaultOptions,globalService),GlobalService]
        },GlobalService
    ],bootstrap: [AppComponent],})
export class AppModule { }

但是现在当我在组件中使用它时,它没有向服务器发送任何请求,并且在控制台中通过以下错误：

EXCEPTION: Error: Uncaught (in promise): TypeError: Cannot read property 'toString' of null

我使用http的组件如下：

import { Component,OnInit } from '@angular/core';
import { Http } from '@angular/http';

@Component({
    templateUrl: '../../templates/home/home.html'
})
export class HomeComponent implements OnInit {

    constructor(private http: Http) {}

    ngOnInit() {
        this.http.get('/home')
            .subscribe((data) => {

            });
    }
}

有人可以引导吗？